Mechanical bowel preparation for elective colorectal surgery (Review) pot

Mechanical bowe l preparation for elec tive colorectal surgery
(Review)
Guenaga KKFG, Atallah ÁN, Castro AA, Matos D, Wille-Jørgensen P
This is a reprint of a Cochrane review, prepared and maintained by The Cochrane Collaboration and published in The Cochrane Library
2008, Issue 4

Mechanical bowel preparation for elective colorectal surgery (Review)
Copyright © 2008 The Cochrane Collaborat ion. Published by John Wi ley & Sons, Ltd.
T A B L E O F C O N T E N T S
1HEADER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3PLAIN LANGUAGE SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3BACKGROUND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3OBJECTIVES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3METHODS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9AUTHORS’ CONCLUSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9ACKNOWLEDGEMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
11CHARACTERISTICS OF STUDIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
19DATA AND ANALYSES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
20Analysis 1.1. Comparison 1 Mechanical bowel preparation versus no preparation, Outcome 1 Anastomosis l eakage
stratified for colonic or rectal surgery. . . . . . . . . . . . . . . . . . . . . . . . . . .
22Analysis 1.2. Comparison 1 Mechanical bowel preparation versus no preparation, Outcome 2 Overall anastomotic
leakage for colorectal surgery. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
23Analysis 1.3. Comparison 1 Mechanical bowel preparation versus no preparation, Outcome 3 Mortality. . . . .
23Analysis 1.4. Comparison 1 Mechanical bowel preparation versus no preparation, Outcome 4 Peritonitis. . . . .
24Analysis 1.5. Comparison 1 Mechanical bowel preparation versus no preparation, Outcome 5 Reoperation. . . .
24Analysis 1.6. Comparison 1 Mechanical bowel preparation versus no preparation, Outcome 6 Wound infection. .
25Analysis 1.7. Comparison 1 Mechanical bowel preparation versus no preparation, Outcome 7 Infectious extra-

abdominal complications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
26Analysis 1.8. Comparison 1 Mechanical bowel preparation versus no preparation, Outcome 8 Non-infectious extra-
abdominal complications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
26Analysis 1.9. Comparison 1 Mechanical bowel preparation versus no preparation, Outcome 9 Surgical site infections.
27Analysis 1.10. Comparison 1 Mechanical bowel preparation versus no preparation, Outcome 10 Sensitivity analysis 1 -
Studies with dubious randomisation procedure excluded. . . . . . . . . . . . . . . . . . . .
29Analysis 1.11. Comparison 1 Mechanical bowel preparation versus no preparation, Outcome 11 Sensitivity analysis 2 -
Studies published as abstract only e xcluded. . . . . . . . . . . . . . . . . . . . . . . .
31Analysis 1.12. Comparison 1 Mechanical bowel preparation versus no preparation, Outcome 12 Sensitivity analysis 3 -
Studies including children excluded. . . . . . . . . . . . . . . . . . . . . . . . . . .
33Analysis 1.13. Comparison 1 Mechanical bowel preparation versus no preparation, Outcome 13 Sensitivity analysis 4 -
Studies including patients without anastomosis excluded. . . . . . . . . . . . . . . . . . . .
35WHAT’ S NEW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
36HISTORY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
36CONTRIBUTIONS OF AUTHORS . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
37DECLARATIONS OF INTEREST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
37SOURCES OF SUPPORT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
37NOTES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
37INDEX TERMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
iMechanical bowel preparation for elective colorectal surgery (Review)
Copyright © 2008 The Cochrane Collaborat ion. Published by John Wi ley & Sons, Ltd.
[Intervention review]
Mechanical bowel preparation for elective colorectal surge ry
Katia KFG Guenaga
1
, Álvaro N Atallah
2
, Aldemar A Castro
3
, Delcio Matos

4
, Peer Wille-Jørgensen
5
1
Surgical Gastroenterology Department, Ferderal University of São Paulo, Guarujá, Brazil.
2
Brazilian Cochrane Centre, Universidade
Feder al de São Paulo / Escola Paulista de Medicina, São Paulo, Brazil.
3
Department of Public Health, State University of Heath
Science, Maceió, Brazil.
4
Brazilian Cochrane Centre, Universidade Federal de São Paulo, São Paulo, Brazil.
5
Department of Surgical
Gastroenterology K, Bispebjerg Hospital, Copenhagen NV, Denmark
Contact address: Katia KFG Guenaga, Surgical Gastroenterology Department, Ferderal University of São Paulo, Marivaldo Fernandes,
152 apto. 13, Guarujá, São Paulo, 11 440-050, Brazil.
(Editorial group: Cochrane Colorectal Cancer Group.)
Cochrane Database of Systematic Reviews, Issue 4, 2008 (Status in this issue: Edited)
Copyright © 2008 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
DOI: 10.1002/14651858.CD001544.pub2
This version first published online: 24 January 2005 in Issue 1, 2005. Re-published online with edits: 8 October 2008 in Issue 4,
2008.
Last assessed as up-to-date: 20 October 2004. (
Dates and statuses?)
This record should be cited as: Guenaga KKFG, Atallah ÁN, Castro AA, Matos D, Wille-Jørgensen P. Mechanical bowel
preparation for elective colorectal surgery. Cochrane Database of Systematic Reviews 2005, Issue 1. Art. No.: CD001544. DOI:
10.1002/14651858.CD001544.pub2.
A B S T R A C T

Background
For over a century the presence of bowel content during surgery has been linked to anastomotic leakage. Mechanical bowel preparation
has been considered an efficient agent against leakage and infectous complications. This dogma is not based on solid evidence, but on
observational data and expert’s opinions.
Objectives
To dete rmine the effectiveness and safety of prophylactic mechanical bowel preparation for morbidity and mortality rates in elective
colorectal surgery.
Search strategy
We searched MEDLINE, EMBASE, LILACS, and the Cochrane Central Register of Controlled Trials. We also searched relevant
medical journals, and conference proceedings from major gastroenterological congresses and contacted experts in the field. We used
the search strategy described by the Colorectal Cancer Review Group, without limitations for date of publication and language. I
Selection criteria
Randomised, cl inical trials that compared any strategy in mechanical bowel preparation with no mechanical bowel preparation.
Data collection and analysis
Data were independently extracted by the reviewers and cross-checked. The same reviewers assessed the methodological quality of each
trial. Details of the randomisation (generation and concealment), blinding, whether an intention-to-treat analysis was done, and the
number of patients lost to follow-up was recorded. For analysis the Peto odds ratio (OR) was used as defaults.
Main results
1Mechanical bowel preparation for elective colorectal surgery (Review)
Copyright © 2008 The Cochrane Collaborat ion. Published by John Wi ley & Sons, Ltd.
Of the 1592 patients (9 trials), 789 were allocated to mechanical bowel preparation (Group A) and 803 to no preparation (Group B)
before elective colorectal surgery. For anastomotic le akage (main outcome) the results were:
- Low anterior resection: 9.8% (11 of 112 patients in Group A) compared with 7.5% (9 of 119 patients in Group B); Peto OR 1.45,
95% confidence interval (CI): 0.57 to 3.67 (non-significant);
- Colonic surgery: 2.9% (Group A) compared with 1.6% (Group B) ; Peto OR 1.80, 95% CI: 0.68 to 4.75 (non-significant);
Overall anastomotic leakage: 6.2% (Group A) compared with 3.2% (Group B); Peto OR 2.03, 95% CI: 1.276 to 3.26 (p=0.003).
For the secondary outcome of wound infection the result was: 7.4% (Group A) compared with 5.4% (Group B); Peto OR 1.46, 95%
CI: 0.97 - to 2.18 (p=0.07);
Sensitivity analyses excluding studies with dubious randomisation, studies published as abstracts only, and studies involving children
did not change the overall conclusions

Authors’ conclusions
There is no convincing evidence that mechanical bowel preparation is associated with reduced rates of anastomotic leakage after elective
colorectal surgery. On th e contrary, there is evidence that this intervention may be associated with an increased rate of anastomotic
leakage and wound complications. It is not possible to be conclusion on the latter issue because of the clinical hete r ogeneity of
trial inclusion criteria, methodological inadequacies in tr ial (in particular, poor reporting of concealment and allocation), potential
performance biases, and failure of intention-to-treat analyses. Nevertheless, the dogma that mechanical bowel preparation is necessary
before elective colorectal surgery should be reconsidered.
2Mechanical bowel preparation for elective colorectal surgery (Review)
Copyright © 2008 The Cochrane Collaborat ion. Published by John Wi ley & Sons, Ltd.
P L A I N L A N G U A G E S U M M A R Y
Key findings: Preoperative mechanical bowel preparation before colorectal sur g ery does not reduce anastomotic leakage.
Preoperative mechanical bowel preparation before colorectal surgery is a widely-practised treatment, but its efficacy has never been
proven outside observational studies and animal experiments.
This systematic review of nine trials (1592 patients) found that there is no convincing evidence that mechanical bowel preparation is
associated with reduced rates of anastomotic leakage after elective colorectal surgery, but on the contrary, there is evidence that this
intervention may be associated with an increased rate of anastomotic leakage and wound complications.
There was no difference in other outcomes, such as mortality, peritonitis, re-operation, infectious extra-abdominal complication, non-
infectious extra-abdominal complication, and surgical site infection.
Mechanical bowel preparation before colorectal surgery cannot be recommended as routine.
B A C K G R O U N D
The impor tance of efficient mechanical bowel preparation in pre-
venting infectious complications and anastomotic dehiscence after
colorectal surger y has been adogma among surgeonsfor more than
a century (
Halsted 1887; Thornton 1997). Clinical experiences
and observational studies have shown that mechanical removal of
gross faeces from the colon has been associated with decreased
morbidity and mortality in patients undergoing operations of the
colon (
Nichols 1971). One author (Chung 1979) was categorical:

“One of the most important factors within the control of the sur-
geon, that affect the outcome of a col onic operation, is the degree
of emptiness of the bowels”.
An early randomised clinical trial questioned this view and con-
cluded that vigorous mechanical bowel preparation is not neces-
sary (
Hughes 1972). Omission of enemas and bowel washes from
the preoperative procedures will be welcomed by both patients
and nursing staff.
One trial (
Irving 1987) questioned the necessity of preoperative or
intra operative mechanical bowel preparation of the colon, before
primary anastomosis. The authors argue that preoperative bowel
preparation is time-consuming, expensive, and unpleasant for pa-
tients - even dangerous on occasion - and completely unnecessary.
Traditionally, “bowel preparation” has been used to reduce faecal
mass and also bacterial counts. Most surgeons consider mechan-
ical bowel preparation to be essential, and the systematic admin-
istration of appropriate antibiotics has been shown effective in re-
ducing infectious complications in numerous randomised trials.
Furthermore, mechanical bowel preparation is recommended by
many guidelines from surgical associations and scientific societies
(
ASCGBI 2001; Moore 1999; SIGN 1997).
Different methods of mechanical bowel preparation have bee n
tested and approved and the potential danger of having faeces
in contact with a newly performed anastomosis when the colon
was not prepared has been discussed (
Grabham 1995 ; Mealy
1992

). Both experimental studies (Smith 1983; O’Dwyer 1989;
Schein 1995), and clinical trials inemergency surgery (Baker 1990;
Dorudi 1990; Duthie 1990) have been published in order to sup-
port this theory.
Two randomised trials from Ireland and Brazil concluded that the
role of bowel preparation in colorectal surgery requires re-evalua-
tion (
Burke 1994; Santos 1994). If bowel preparation is shown to
be needless, it could mean a shorter hospital stay for the patient
and avoidance of the potential complications associated with the
cleansing procedure such as gastric intolerance, low serum potas-
sium level, bowel explosion, mucosal lesions, electrolyte distur-
bance and fluid overload.
Analysed in isolation, the results of published trials have not shown
any significant difference in outcomes between patients who un-
derwent mechanical bowel preparation and those who did not,
but as the individual studies contain a high risk of a statistical type
II er ror it seemed justified to perform a meta-analysis.
O B J E C T I V E S
To determine the necessity of prophylactic mechanical bowel
preparation in patients undergoing elective colorectal surgery.
The incidence of anastomotic dehiscence is increasing as more
anal the anastomosis is performed (
Goligher 1970). Because bowel
preparation might have different effect in colon and rectum, we
will stratify the analyses for colon and rectum separately whenever
possible.
M E T H O D S
Criteria for consideri ng stu dies for this review
Types of studies

3Mechanical bowel preparation for elective colorectal surgery (Review)
Copyright © 2008 The Cochrane Collaborat ion. Published by John Wi ley & Sons, Ltd.
(i) Randomised clinical trials comparing preoperative mechanical
bowel preparation versus no preparation (or placebo) in
(ii) patients undergoing elective colorectal surgery and in which
(iii) the primary outcome (anastomotic leakage) is clearly stated
in both treatment arms.
To be included in this review, trials had to meet all three criteria.
EXCLUSION CRITERIA:
Studies evaluating two or more different cleansing methods; stud-
ies including patients undergoing emergency surgery.
Types of participants
Patients undergoing elective colorectal surgery.
Types of interventions
Any strategy in mechanical bowel preparation for patients under-
goingelective colorectal surgery compared to no mechanical bowel
preparation.
Types of outcome measures
PRIMARY OUTCOME MEASURES:
1) A nastomotic leakage, defined as discharge of faeces from the
anastomosis site, externalising through the drainage opening or
the wound incision; or just th e existence of an abscess adjacent to
the anastomosis site. The anastomotic leakage was confirmed by
either clinical or radiological investigation.
The type of surgery and anastomosis site were stratified in:
A: Low anterior resection, extra-peritoneal anastomosis (rectum
considered extra-peritoneal);
B: Colonic surgery, intra-peritoneal anastomosis.
2) Overall anastomotic leakage: total number of anastomotic de-
hiscence in all of colon and rectum.

SECONDARY OUTCOME MEASURES:
3) Mortality: number of postoperative deaths related to the surgery.
4) Per itonitis: presence of postoperative infections at the abdomi-
nal cavity, localized (abscess) or not.
5) Re-operation: surgical re-intervention for anastomotic compli-
cation.
6) Wound infection: defined as a discharge of pus from th e ab-
dominal wound.
7) Infectious extra-abdominal complication: postoperative infec-
tious complication at extra-abdominal site.
8) Non-infectious extra-abdominal complications (e.g. deep ve-
nous thrombosis, cardiac complications, wound rupture).
9) Overall infections in surgical sites.
SENSITIVITY AND SUBGROUP ANALYSES
10) Anastomotic leakage and wound infection in studies with
adequate randomisation.
11) Anastomotic leakage and wound infection in studies published
as full articles.
12) Anastomotic leakage and wound infection in studies only deal-
ing with adult patients.
13) Anastomotic leakage and wound infection in studies in which
bowel continuity was restored.
Search methods for identification of studies
See: Collaborative Colorectal Cancer Review Group search strat-
egy (
Wille-Jørgensen 1999).
The studies were identified from the following sources: MED-
LINE, EMBASE, CINAHL, LILACS, SCISEARCH, Controlled
Clinical Trials Database, Trials Register of the Cochrane Colorec-
tal Cancer Group, and the Cochrane Central Register of Con-

trolled Trials (CENTRAL). Reference lists were checked, hand-
searching was carried out, and through letters sent to study au-
thors. Conference proceedings from major gastrointestinal confer-
ences (World Congress of Gastroenterology, Annual Meetings of
American Sociery of Colon and Rectal Surgery, Annual meetings
of Association of Coloproctology of Great Britain and Ireland,
Tripartites meetings) were scrutinised back to 1994 (last possible
retrieval of abstract-material). There were no limits regarding lan-
guage, date, or other restrictions in the searches. Al l searches were
performed up to July 2004.
Search strategy:
#1 Cochrane Collaboration search strategy for randomised con-
trolled trials (
Handbook 2004)
#2 Tw INTESTIN* or Tw BOWE L
#3 Tw LARGE or Tw GROSSO or Tw GRUES O
#4 #2 and #3
#5 Tw COLO* or Tw CECO
#6 Tw RECT* or Tw RET*
#7 #4 or #5 or #6
#8 #3 and #7
#9 Tw PREPARA*
#10 Tw SURGERY or SURGICAL
#11 #8 and #9 and #10
#12 #1 and #11
Data collection and an alysis
LOCATING AND SELECTING STUDIES
The reviewers (KFG and PWJ) independently selected the trials to
be included in this review. Disagreement on selection was solved
in a consensus meeting. Only studies designed and stated as ran-

domised controlled trials were considered for inclusion.
CRITICAL APPRAISAL OF STUDIES
The re viewers assessedthe methodological quality of each trial. We
recorded details of the randomisation method, blinding, whether
anintention-to-treatanalysiswas done, and the number ofpatients
lost to follow-up to evaluate the risk of bias in the individual
studies (
Handbook 2004). We assessed the external validity of the
studies in an analysis of the characteristics of the participants and
the interventions as collected below.
COLLECTING DATA
4Mechanical bowel preparation for elective colorectal surgery (Review)
Copyright © 2008 The Cochrane Collaborat ion. Published by John Wi ley & Sons, Ltd.
We included studies in which allocationconcealment was regarded
adequate were included. A few studies with unclear allocation
concealment were included as well . The reviewers independently
extracted and cross-checked the data. The result of each trial was
summarised in 2 x 2 tables for each outcome.
We evaluated study validity according to participants and inter-
ventions:
PARTICIPANTS: Category of disease (colorectal cancer, inflam-
matory disease, megacolon, polyposis, diverticular disease), gen-
der, age, topography, operative procedure, antibiotic therapy, sur-
geon experience. The calculation of the sample size and the sample
representativeness was observed.
INTERVENTIONS: Types of mechanical bowel preparation: an-
terograde(oral) or retrograde (enemas)versus no mechanical bowel
preparation.
Information data from the studies published more than once, was
only included once.

Data were entered into Review Manager 4.2 by single data-entry
by KFG and controlled by PWJ.
ANALYSING AND PRESENTING RESU LTS
If appropriate we stratified the studies for different meta-analy-
sis (Review Manager 4,2) according to the analysis of the defined
outcomes. We used various techniques: in the dichotomous out-
come measures, the combined logarithm of the Peto Odds Ratio
(fixed effect model) was used as default. We performed a te st for
statistical heterogeneity in each case. If we detected heterogeneity,
results were reported as Odds Ratio using random-effects mod-
elling. For the analysis, we reviewed only patients who underwent
elective colorectal surgery; according to type of interventions, type
of participants, to assess whether there were important differences
between them. A ll inclusion criteria had to be met.
We assessed statistical heterogeneity and potential publication bias
in th e results of the meta-analysis both by inspection of graphical
presentations (“funnel plot”: plotting the study weight or sample
size (on the “Y” axis) against the Odds Ratio (on the “x” axis)
and by calculating a test of heterogeneity (standard chi-squared
test on N degrees of freedom where N equals the number of tri-
als contributing data minus one). The funnel plot is possible for
outcomes described in five or more studies. Three possible reasons
for heterogeneity were pre-specified: (i) that responses differ ac-
cording to difference in the quality of the trial; (ii) that response
differ according to sample size; (iii) that response differ according
to clinical heterogeneity. If we detected heterogeneity, sensitivity
analyses were performed in subgroups.
SENSITIVITY ANALYSIS.
We used a fixed sample model with Peto Odds ratio was used as
default. If heterogeneity was apparent, a random effects model was

applied.
IMPROVING AND UPDATING THIS REVIEW
As a minimum, updates will be considered on an biannual basis.
This is the first update performed two years after the first appear-
ance in The Cochrane Library. Three additional studies have been
included, and one study previously included as an abstract is now
included as a full paper version.
R E S U L T S
Description of studies
See:
Characteristicsof included studies; Characteristics of excluded
studies
.
We identified fourteen studies of which nine were included, and
five trials were excluded. The reason for exclusion was absence
of a control group (
Irving 1987, Dorudi 1990, Duthie 1990),
elemental diet in the control group (
Matheson 1978), or lack of
description of the primary outcome and insufficient description
of the secondary outcomes (
Hughes 1972) see “Characteristics of
excluded studies”.
One of theincluded studies was published in Portuguese (
Fillmann
1995
), and identified in the Lilacs database. One study was in
Spanish (
Tabusso 2002). The others were published in English
language. Three studies were published as abstracts only (Brown-

son 1992,
Bucher 2003, Fa-Si-Oen 2003). Data from the latter
study were retrieved from another publication (
Slim 2004).
Three new studies were identified and included in this update
(
Bucher 2003, Tabusso 2002, Fa-Si-Oen 2003). Two were con-
ference proceedings (
Bucher 2003, Fa-Si-Oen 2003).
TYPES OF PARTICIPANTS
The inclusion criteria was the same for all studies: patients ad-
mitted for elective colorectal surgery. O ne trial (
Santos 1994) in-
cluded children. Two studies included patients without anasto-
mosis (
Fillmann 1995, Santos 1994); one study (Brownson 1992)
excluded these patients in only one of the outcomes: anastomosis
leakage; two of them (
Burke 1994, Miettinen 2000) excluded pa-
tients for whom bowel continuity was not restored.
In two of the new trials included in the review (
Bucher 2003 ,
Tabusso 2002) one of the inclusion criteria was patients undergo-
ing elective “left-sided” colorectal surgery. One new trials stated
only “elective colorectal surgery” (
Fa-Si-Oen 2003).
None of the studies reported the use of preoperative adjuvant
chemotherapy or radiation. Seven stated use of prophylactic an-
tibiotics, and there was no information on this from two studies
(

Zmora 2003, Bucher 2003) .
Five trials (
Burke 1994, Fillmann 1995, Miettinen 2000, Santos
1994
, Zmora 2003 ) described the two allocation groups as being
equal according to gender, age, types of operation, and diagnosis.
Three of them (Brownson 1992,
Bucher 2003, Fa-Si-Oen 2003)
did not give details. One (
Tabusso 2002 ) described a statistic
difference betwee n the two groups regarding age, hemoglobinlevel
and serum albumin.
The criteria for excl usion of patients were reported in different
ways: A) patients who had been taken antibiotics for at least 15
days before surgery, or if there was evidence of infection, or any as-
sociated disease requiring antibiotic therapy, and patients in whom
5Mechanical bowel preparation for elective colorectal surgery (Review)
Copyright © 2008 The Cochrane Collaborat ion. Published by John Wi ley & Sons, Ltd.
the mechanical bowel preparation was not fe asible (Santos 1994);
B) any patients wh o could not tolerate the preparation; C) patients
who had bowel preparation for colon one week before surgery,
patients who where unable to drink the solution, patients not re-
quiring opening of the bowel, and one patient who refused to be
randomised (
Miettinen 2000); D: Two trials excluded patients in
whom bowel continuity was not restored (Burke 1994, Miettinen
2000). One trial (Brownson 1992) excluded the patients in whom
bowel continuity was not restored in the analysis of the primary
outcome: anastomotic leakage. E: One of the trials (
Zmora 2003)

included only patients with primary anastomosis. F) no patients
were excluded, (
Fillmann 1995) ; G) did not give details on ex-
clusion (Brownson 1992, Bucher 2003, Tabusso 2002, Fa-Si-Oen
2003
).
Two studies, (
Fillmann 1995 , Santos 1994 ), included patients
undergoing any of the following surgical procedures: abdomi-
nal excision of the rectum, Hartman’s procedure, defunctioning
colostomy, colonic anastomosis with colostomy; some of the pa-
tients without anastomosis. One of the trials (
Tabusso 2002) in-
cluded patients without anastomosis.
TYPES OF INTERVENTIONS
All of the included studies compared mechanical bowel prepara-
tion with no preparation of the bowel prior to colorectal surgery :
Preparation of the bowel was either polyethy lene glycol ele ctr olyte
solution; laxatives (mineral oil, agar and phenolphthalein); man-
nitol; enemas (water, 900 ml; glycerin, 100 ml); sodium picosul-
phate 10 mg; Bisacodyl (10 mg)+enemas; and diets, low and non-
residue.
Only two studies mentioned the experience of the surgeon. wo
of them (
Burke 1994, Miettinen 2000) described the operations
performed by or under the supervision of a consultant surgeon;
one (
Santos 1994), described the operations performed by senior
residents.
The duration of follow-up was described as follows: A ) 30 days or

until h ospital discharge (
Santos 1994); B) 30 days after surgery
(Fillmann 1995 , Zmora 2003 ) ; C) 1-2 months after surgery
(
Miettinen 2000); D) le ss clearly (Burke 1994, Tabusso 2002):
7 days after surgery ; E) not described (Brownson 1992,
Bucher
2003
, Fa-Si-Oen 2003).
TYPES OF OUTCOMES MEASUREMENTS
PRIMARY OUTCOMES
1) Anastomotic leakage: two of the studies (
Burke 1994; Miettinen
2000
) stratified the anastomosis between rectal and colonic. Data
on stratification were obtained by personal contact with two au-
thors (
Zmora 2003, Santos 1994). The others (Brownson 1992,
Fillmann 1995, Tabusso 2002, Fa-Si-Oen 2003) did not refer to
the site of the anastomosis. Two studies described all anastomosis
to be left-sided (
Bucher 2003, Zmora 2003).
2) Overall anastomotic leakage: All the included studies described
this outcome.
SECONDARY OUTCOMES
3) Mortality: five of the studies described this outcome (
Burke
1994, Fillmann 1995, Miettinen 2000, Santos1994, Zmora2003).
4) Peritonitis: four of the studies (Brownson 1992,
Fillmann 1995,

Miettinen 2000,Tabusso 2002) included this.
5) Re operation: four trials described this outcome (
Burke 1994,
Fillmann 1995, Miettinen 2000, Santos 1994).
6) Wound infection: all of the included studies described it
(Brownson 1992,
Bucher 2003, Burke 1994 , Fa-Si-Oen 2003,
Fillmann 1995, Miettinen 2000 , Santos 1994, Tabusso 2002 ,
Zmora 2003).
7) Infectious extra-abdominal complication: two studies
(
Fillmann 1995; Miettinen 2000) described this outcome.
8) Non-infectious extra-abdominal complication: four studies
(
Burke 1994; Fillmann 1995; Miettinen 2000, Zmora 2003) de-
scribed this.
9) Surgical site infection: two studies (
Miettinen 2000 , Zmora
2003
).
OTHER CHARACTERISTICS
None of the studies contained an indication of how the sample
size was calculated. One author (
Fillmann 1995) replied to our
enquiry that the sample size was calculated, but didn’t give more
details. Two of the studies(
Burke 1994, Miettinen 2000) described
the sampling as consecutive.
SENSITIVITY ANALYSIS AND SUBGROUP ANALYSES ON
ANASTOMOTIC LEAKAGE AND WOUND INFECTION

In five of the studies (Brownson 1992,
Bucher 2003, Burke 1994,
Tabusso 2002, Fa-Si-Oen 2003) the allocation method was not
well-described . A sensitivity analysis was performed leaving out
these studies (outcome 10). As three of the studies (Brownson
1992,
Bucher 2003; Fa-Si-Oen 2003) were published as abstracts,
an analysis was performed, leaving out these studies (outcome 11).
In one study (
Santos 1994) children were included. This study was
excluded in the third sensitivity analysis (outcome 12). In three of
the trials (
Fillmann 1995, Santos 1994, Tabusso 2002) patients
without anastomosis were included and an analysis was carried out
without these studies(outcome 13).
Risk of bias in included studies
None of the studies used an intention to treat analysis.
SELECTION BIAS (Sy ste matic differences in comparison
groups)
In two trials (
Santos 1994, Miettinen 2000), the allocation process
was described as randomised cards. One author (
Fillmann 1995)
replied to our enquiries and described the process using a random
number table. In one study a computer generated list was used
(
Zmora 2003). In these studies the allocation process was con-
sidered sufficient. In the others (Brownson 1992,
Bucher 2003,
Burke 1994, Tabusso 2002, Fa-Si-Oen 2003), the allocation pro-

cess was not clearly specified and thus considered unclear, leading
to a sensitivity analysis. In general, the allocation concealment in
all studies was not described. This is known to create biases (
Juni
2002
).
6Mechanical bowel preparation for elective colorectal surgery (Review)
Copyright © 2008 The Cochrane Collaborat ion. Published by John Wi ley & Sons, Ltd.
PERFORMANCE BIAS (Systematic differences in care pr ovided
apart from the intervention being evaluated)
None of the studies reported the use of preoperative adjuvant
chemotherapy or radiation. They all used prophylactic antibiotics,
and all but two (Brownson 1992,
Bucher 2003 ) de scribed the
two allocation groups as being equal according to gender, age,
types of operation, and diagnosis. Another one (
Tabusso 2002)
indicated a difference between the all ocation groups with the age,
haemoglobin level and serum albumin. No relevant performance
bias was thus detected
BLINDING
One trial (
Fillmann 1995) described as a double-blind, in which
orange juice was used as placebo, must be considered only to the
surgeon due to the differences in taste for the patient between
the intervention and the control. One study (
Burke 1994 ) was
described as a single-blind study, as the surgeons were aware of
allocation of patients to bowel preparation. The rest of the studies
contained no mention of blinding methods.

ATTRITION BIAS (Systematic differences in withdrawals from
the trial)
Brownson 1992,
Bucher 2003, Tabusso 2002, Fa-Si-Oen 2003did
not describe withdrawals or dropouts.
Burke 1994 had 9.1% (17/
186 patients) withdrawal, and no dropout;
Santos 1994 , with
5% (8/157 patients) withdrawal, and no dropout, and Zmora
2003
8.6% (35/415). Two trials (Fillmann 1995, Miettinen 2000)
described that all patients completed the study. The author of
Fillmann 1995 supplied this information on written request.
DETECTION BIAS (Systematic differences in outcomes assess-
ment)
No studies described any kind of concealment of assessment was
described, except for the blinding procedure in the Fillmann-study
(
Fillmann 1995).
(
Burke 1994) measured the incidence of anastomotic leakage in
the first half of the study by performing water soluble contrast
enemas in all patients. In the second half of the study, enema was
used on clinical suspicion of leakage due to the experience that
two of the six l eaks on day 7 after surgery occurred immediately
after administration of the routine water-soluble contrast enema.
The contrast enema was used on clinical suspicion in four trials
(
Burke 1994; Miettinen 2000; Santos 1994; Fillmann 1995).
For the diagnostics of the various outcomes, the trials:

a) did not describe the methodology (Brownson 1992,
Bucher
2003
, Tabusso 2002, Fa-Si-Oen 2003);
b) used clinical symptoms and laboratory results (
Burke 1994 ,
Santos 1994);
c) used laboratory results in patients inwh om the clinical diagnosis
was unclear (
Fillmann 1995);
d) described all of the meth ods used for diagnosing the complica-
tions (
Miettinen 2000, Zmora 2003).
As stated in the beginning of this section, none of the studies used
an intention to treat analysis. Eight patients were excluded after
randomisation from one study (
Santos 1994), 17 from another
(Burke 1994), and 35 from a third (Zmora 2003). In two studies
no patients were excluded (
Fillmann 1995, Miettinen 2000). The
others, gave no information on exclusion (Brownson 1992,
Bucher
2003
, Tabusso 2002, Fa-Si-Oen 2003).
Effects of interventions
Nine randomised controlled trials including a total of 1592 pa-
tients, of whom 789 were allocated for mechanical bowel prepa-
ration (Group A), and 803 for no bowel preparation (Group B)
prior to elective colorectal surgery were included.
The results of each outcome were:

PRIMARY OUTCOMES:
1) Anastomotic leakage - stratified:
A) Low anterior resection: 9.8% (11 of 112 patients in Group A)
compared to 7.5% (9 of 119 patients in Group B); Peto OR 1.45,
95% CI: 0.57 to 3.67 (non-significant) - no statistical heterogene-
ity (
Burke 1994, Miettinen 2000, Santos 1994, Zmora 2003);
B) Colonic surgery: 2.9% (11 of 367 patients in Group A) com-
pared to 1.6% (6 of 367 patients in Group B) ; Peto OR 1.80,
95% CI: 0.68 to 4.75 (non-significant) - no statistical heterogene-
ity (
Burke 1994, Miettinen 2000, Santos 1994, Zmora 2003);
2) Overall anastomotic leakage:
Overall anastomotic leakage: 6.2% (48 of 772 patients in Group
A) compared to 3.2% (25 of 777 patients in Group B); Peto OR
2.03, 95% CI: 1.276 to 3.26 (p=0.003) - no statistical hetero-
geneity. (Brownson 1992, Bucher 2003, Burke 1994, Fillmann
1995
, Santos 1994 , Miettinen 2000 , Tabusso 2002 , Zmora
2003
,Fa-Si-Oen 2003);
SECONDARY OUTCOMES:
3) Mortality: 1% (5of 509patients in Group A) compared to 0.6%
(3 of 516 patients in Group B); Peto OR 1.72, 95% CI: 0.43 to
6.95 (non-significant) - no statistical heterogeneity (
Burke 1994,
Fillmann 1995, Miettinen 2000, Santos 1994, Zmora 2003);
4) Peritonitis: 5.7% ( 16 of 278 patients in Group A) compared
to 2.5% (7 of 275 patients in Group B); Peto OR 2.28, 95% CI:
0.99 to 5.25) (p=0.05) - no statistical heterogeneity (Brownson

1992,
Fillmann 1995, Miettinen 2000, Tabusso 2002);
5) Reoperation: 4.0% ( 16 of 393 patients in Group A) compared
to 2.2% (9 of 392 patients in Gr oup B); Peto OR 1.80, 95%
CI: 0.81 to 3.98) (non-significant) - no statistical heterogeneity
(Bucher 2003 , Burke 1994 , Fillmann 1995 , Miettinen 2000 ,
Santos 1994,Tabusso 2002);
6) Wound infection: 7.4% (59 of 789 patients in Group A) com-
paredto 5.4% (43of 803 patientsin GroupB); PetoOR 1.46, 95%
CI: 0.97 to 2.18 (p=0.07) - no statistical heterogeneity (Brownson
1992,
Bucher 2003, Burke 1994, Fillmann 1995, Miettinen 2000,
Santos 1994, Tabusso 2002, Zmora 2003);
7) Infectious extra-abdominal complication: 8.3% ( 14 of 168
patients in Group A) compared to 9.4% (15 of 159 patients in
Group B); Peto OR, 95%: 0.87 (0.41 to 1.87) (non-significant) -
no statistical heterogeneity (
Fillmann 1995, Miettinen 2000);
7Mechanical bowel preparation for elective colorectal surgery (Review)
Copyright © 2008 The Cochrane Collaborat ion. Published by John Wi ley & Sons, Ltd.
8) Non-infectious extra-abdominal complication: 16.8% ( 73 of
433 patients in Group A) compared to 16.1% (71 of 439 patients
in Group B); Peto OR 1.19, 95% CI: 0.61 to 2.32 (non-signifi-
cant) - no statistical heterogeneity (
Burke 1994, Fillmann 1995,
Miettinen 2000);
9) Surgical site infection: 9.8% (31 of 325 patients in Group A )
compared to 8.3% (27 of 322 patients in Group B); Peto OR
1.20, 95% CI: 0.70 to 2.05 (non-significant) - no statistical het-
erogeneity (

Miettinen 2000, Zmora 2003);
SENSITIVITY ANALYSES:
Applying the random effects model in the only statistical signifi-
cant outcome still shows significant difference in f avour of avoid-
ing cleansing. OR 2.09, CI: 1.16 to3.78, p =0.01.
10) Excluding the four studies where the allocation procedure was
considered unclear did not change the Peto OR substantially for
the two clinical most important outcomes (anastomosis leakage
and wound infection), although the significance disappeared due
to the smaller total the sample size (p = 0.1 and 0.14 respectively).
11) Excluding the two studies only presented as abstracts substan-
tially changed neither the Peto OR nor the level of significance for
the two analysed outcomes.
12) Excluding the study which included children did not change
the significant higher incidence of anastomotic leakage in the me-
chanical bowel preparation group, but the potential negative effect
of cleansning on wound infection became smaller.
13) Excluding the studies that included patients without anasto-
mosis for the outcome anastomosis leakage, the Peto OR was 2.14
(p = 0.03) compared with the Peto OR of 2.29 (p = 0.002) before
these studies were excluded. There was no substantially difference
for the wound infection outcome.
D I S C U S S I O N
In 1987 Irving (
Irving 1987) questioned the efficacy of mechanical
bowel cleansing. The study was criticised by the editor (Johnston
1987
): “the paper which challenges accepted surgical practice, is a
veritable little bomb of a paper, brief, iconoclastic, and disrespect-
ful of hallowed tradition in colorectal surgery”. At th at time, the

mechanical bowel preparation was an incontestable routine - and
still is according to guidelines from some surgical associations and
scientific societies (ASCGBI 2001; Moore 1999; SIGN 1997),
while other guidelines are now more up to date (
Kronborg 2002).
The nine included trials were all prospective andrandomised. Typ-
ically for studies of surgical practice, the allocation procedure was
not very well described, but was considered adequate in half of
the studies. Most of the studies were performed before the im-
portance of allocation concealment (
Schulz 1996) became general
knowledge. Only one of the studies trie d to include some kind of
blinding (
Fillmann 1995) - an almost impossible task in trials of
this kind. Despite these methodological flaws, the included stud-
ies must be considered of such a scientific value that their conclu-
sions should be taken into consideration, when trying to answer
the question stated under ’objectives’.
We found no convincing evidence that mechanical bowel prepa-
ration before elective colorectal surgery reduces the incidence of
postoperative complications. When looking at the primary out-
come - anastomosis leakage - mechanical bowel preparation was
dangerous when looking at colorectal surgery as a whole (statis-
tically significant result). The subgroup analyses did not alter the
direction of association, although the statistical significance disap-
peared.
The outcome anastomosis leakage was split into leakage after low
anterior resection and leakage after colonic surgery. It was only
possible to obtain results from four authors (
Burke 1994, Santos

1994
, Miettinen 2000 , Zmora 2003 ). After this stratification,
the results tended to favour the group without mechanical bowel
preparation.
Some of the studies included patients in whom bowel continuity
was not restored when analysing the outcome anastomosis leakage
(
Tabusso 2002; Fillmann 1995; Santos 1994). Because the number
of non-anastomotic patients were equally distributed between the
groups so we do not feel this potential bias to be of significance.
None of the studies included an intention to treat-analysis nor had
any of theauthors calculated the sample size before the study. Seven
of the studies must be considered underpowered from the begin-
ning - only the Peruvian study (
Tabusso 2002) showed its own
significance in favour of no cleansing. In this respect, the meta-
analysis is a good tool, and when there is no he terogeneity among
the studies the overall result can be accepted as valid. Allthough
no statistical heterogeneity was found between the outcomes of
the individual studies, some methodological and clinical hetero-
geneity exists. Wheth er or not this should modify the conclusions
is debatable. We have tried with sensitivity-analysis to elucidate
the consequences of th e heterogeneity, and none of the analysis
led to the conclusion that preparation would be of benefit for the
patient. The significance for the primary outcome although dis-
appers in some of the analyses, but the te ndency is still strong,
and always in the same direction - preparation might lead to more
anastomotic leakage. When performing the sensitivity-and sub-
group-analyses the reduced volume of material makes the analyses
statistically underpowered. This increases the risk of a type II error

when evaluating the primary outcome. The Peto Odds Ratio re-
mains almost unchanged during the sensitivity-analyses although
the significance disappears. This strongly supports the conclusion:
Mechanical bowel cleansing leads to more anastomotic dehiscence
in colorectal surgery.
A stratified analysis between colonic and rectal surgery was only
feasible for four studies, andthe results were inconclusive, although
the tendency goes in the same direction as the overall results -
bowel preparation cannot be recommendedin patientsundergoing
elective colorectal surger y.
8Mechanical bowel preparation for elective colorectal surgery (Review)
Copyright © 2008 The Cochrane Collaborat ion. Published by John Wi ley & Sons, Ltd.
Only one of the included trials evaluated the length of hospital
stay (
Tabusso 2002), and found that the group of patients that
underwent mechanical bowel preparation had a longer hospital
stay than the other group of patients (statistically significant). It
would be interesting to know h ow much time is needed to stay at
the hospital before the surgery, just for the bowel to be cleaned.
Analysing the types of interventions, from the table of included
studies, could provide some indication:
A) patients were prepared one day before surgery (Group A); the
patients of Group B have to be at the hospital in a few hours before
surgery (Brownson 1992,
Burke 1994, Miettinen 2000);
B) No difference due to the “doublle-blind” design, (
Fillmann
1995
);
C) needed 5 days for Group A; and 1 day, for Group B (

Santos
1994
);
D) patients were admitted to the hospital 48 hours before the
surgery (
Tabusso 2002). See “Characteristics of included studies”.
In the protocol of the review, we discussed “length of hospital stay”
as an outcome, but the trials did not de scribe this point clearly,
and thus this outcome was excluded from the comparisons.
All included studies and almost all of the excluded studies used
prophylactic antibiotics in each group. This has raised the question
of whether the antibiotic use could explain why no effect of the
mechanical bowel preparation was found. This review cannot give
any substantial information on this matter.
The results of this review do not show any benefit of performing
mechanical bowel preparations. A “semi prepared” colon is usually
full of liquid faeces that can be difficult to control, resulting in
spillage into the peritoneal cavity which can cause significant con-
tamination. By omitting mechanical preparation one overcomes
the problems of the poorly prepared bowel. The content of the
bowel (bulky stools) can be manipulated into the bowel segment
to be resected , enough to make the site of the anastomosis clear.
A U T H O R S ’ C O N C L U S I O N S
Implications for practice
Prophylactic mechanical bowel preparation before colorectal
surgery has not been proven valuable for patients. Controversially
it seems that the preparation might lead to more anastomotic leak-
age and thus the procedure should be omitted.
Implications for research
The re sults of this systematic review showthe necessity of complet-

ing more trials addressing the safety and the clinical effectiveness
of mechanical bowel preparation compared with no preparation
before elective colorectal surgery. Concealment of allocation is im-
perative, especially as such a trial would probably require a multi-
centre design. Stratification between colonic and rectal surgery is
important. The use of pre-operative radiotherapy needs to be reg-
istered. Collaborative (properly designed) randomised controlled
trials that involve a large, representative number of individuals,
with explicit clinical inclusion and exclusion criteria, well defined
hospital discharge criter ia, sufficient duration of follow-up, de-
scription of dropouts and withdrawals, and uniform diagnosis of
all relevant outcome measures should be planned.
A C K N O W L E D G E M E N T S
We want to thank the Cochrane Colorectal Cancer Group for
hosting one of the reviewers (KFG) for three weeks (November,
1999), to finish the review.
We also want to thank Dr. Zmora, Dr. Santos and Dr. Fillmann
for supplying us with supple mentary data.
Thanks to Mr. Henning K. Andersen and Mrs. Ina Fjeldmark for
assisting with th e review, and their special attention, when KFG
was in Copenhagen.
The Valerie Jefferson Fundkindly supported thisreviewfinancially
R E F E R E N C E S
References to studies included in this review
Brownson 199 2 {published data only}
∗
Brownson P, Jenkins AS, Nott D, et al.Mechanical bowel prepa-
ration before colorectal surgery: results of a prospective randomized
trial. Br J Surg. 1992; Vol. 79:461–462.
Bucher 2003 {published data only}

∗
Bucher P, Gervaz P, Erné M, Schmid JF, Chautems R, Huber O,
et al.[Mechanical bowel preparation vs. no preparation in patients
undergoing elective left-sided colorectal surgery: a prospective, ran-
domized trial.]. 2003.
Burke 1994 {published data only}
Burke P, Mealy K, Gillen P, Joyce W, Traynor O, Hyland J. Require-
ment for bowel preparation in colorectal surgery. British Journal of
Surgery 1994;81(6):907–910. [MEDLINE: 8044619]
Fa-Si-Oen 2003 {unpublished data only}
Fa -Si-Oen PR, Buitenweg JA, van Geldere D, deWaard JW, Swank
X, Putter H, et al.The effect of preoperative bowel preparatyion with
polyethylene glycol on surgical outcome in elective open colorectal
surgery - a randomised multicentre trial Fourth Belgian Surgical
Week, Ostende 2003; Vol. –:–.
9Mechanical bowel preparation for elective colorectal surgery (Review)
Copyright © 2008 The Cochrane Collaborat ion. Published by John Wi ley & Sons, Ltd.
Fillmann 1995 {published data only}
∗
Fillmann EEP, Fillmann HS, Fillmann LS. Elective colorectal
surgery without prepare [Cirurgia colorretal eletiva sem preparo]. Re-
vista Brasileira de Coloproctologia 1995;15(2):70–71.
Fillmann HS, Fillmann LS. Elective colorectal surgery without pre-
pare [Cirurgia coloretal eletiva sem preparo.]. São Paulo, 1995.
Miettinen 2000 {published data only}
Miettinen P, Laitinen S, Makela J, Paakkonen M. Bowel prepara-
tion is unnecessary in elective open colorectal surgery. A prospective,
randomized study Digestion. Vienna, 1998; Vol. supplement 3. [:
GaPP0165]
∗

Miettinen RPJ, Laitinen ST, Makela JT, Paakkonen ME. Bowel
preparation with oral polyethylene glycol electrolyte solution vs. no
preparation in elective open colorectal surgery. Diseases of Colon and
Rectum 2000;43(5):669–677.
Santos 1994 {published data only}
Santos JC Jr, Batista J, Sirimarco MT, Guimarães AS, Levy CE.
Prospective randomized trial of mechanical bowel preparation in pa-
tients undergoing elective colorectal surgery. British Journal of Surgery
1994;81(11):1673–1676. [MEDLINE: 7827905]
Tabusso 2002 {published data only}
∗
Tabusso FY, Zapata JC, Espinoza FB, Meza EP, Figueroa ER. Me-
chanical preparation in elective colorectal surgery, a useful practice or
need? [Preparación mécanica et cirgía electiva colo–rectal, costumbre
o necesidad]. Rev Gastreoentero Peru 2002;22(2):152–158.
Zmora 200 3 {published and unpublished data}
∗
Zmora O, Mahajna A, Bar-Zakai B, Rosin D, Hershko D, Shab-
tai M, Krausz MM, Ayalon A. Colon and rectal surgery wothout
mechanical bowel preparation. A randomized prospective trial. Ann
Surg 2003;237(3):363–367. [MEDLINE: 12616120]
References to studies excluded from this review
Dorudi 1990 {published data only}
Dorudi S, Wilson NM, Heddle RM. [Primary restorative colectomy
in malignant left-sided large bowel obstruction]. Annals of the Royal
College of Surgeons of England 1990;72:393–395.
Duthie 1990 {published data only}
Duthie GS, Foster ME, Price-Thomas JM, Leaper DJ. [Bowel prepa-
ration or not for elective colorectal surgery]. Journal of the Royal Col-
lege of Surgeons of Edinburg 1990;35:169–171.

Hughes 19 72 {published data only}
Hughes ESR. [Asepsis in large-bowel surgery]. Annals of the Royal
College of Surgeons of England 1972;51:347–356.
Irving 1987 {published data only}
Irving AD, Scrimgeour D. [Mechanical bowelpreparation for colonic
resection and anastomosis]. British Journal of Surgery 1987;74:580–
581.
Matheson 1978 {published data only}
Matheson DM, Arabi Y, Baxter-Smith D, Alexander-Williams J,
Keighley MRB. [Randomized multicentre trial of oral bowel prepara-
tion and microbials for elective colorectal operations]. British Journal
of Surgery 1978;65(9):597–600.
Memon 1997 {published data only}
Memon MA, Devine J, Freeney J, From SG. [Is mechanical bowel
preparation really necessary for elective left sided colon and rectal
surgery?]. International Journal of Colorectal Disease 1997;12:298–
302.
Additional references
ASCGBI 2001
The Association of Coloproctology of Great Britain a nd Ireland.
Guidelines for the management of colorectal cancer (2001). Guide-
lines for the management of colorectal cancer. London: The Association
of Coloproctology of Great Britain and Ireland, 2001.
Chung 1979
Chung RS, Gurll NJ, Berglund EM. A controlled trial of whole gut
lavage as a method of bowel preparation for colonic operations. Am
J Surg 1979;137:75–81.
Goligher 1970
Goligher JC, Graham NG, De Dombal FT. Anastomotic dehiscence
after anterior resection of rectum and sigmoid. Br J Surg 1970;57(2):

109–118.
Grabham 1995
Grabham JA, Moran BJ, Lane RHS. Defunctiong colostomy for low
anteriorresection: a seletive approach. Br JSurg 1995;82:1331–1332.
Halsted 1887
Halstedt WS. Circular suture of the intestine: an experimental study
Am J Med Sci 1887;94:436–61.
Handbook 2004
Alderson P, Green S, Higgins JPT, editors. Cochrane Reviewers
Handbook 4.2.2 [updated March 2004]. Cochrane Database of Sys-
tematic Reviews 2004, Issue Issue 1.
Johnston 1987
Johnston D. Bowel preparation for colorectal surgery [editorial]. Br
J Surg 1987;74:553–554.
Juni 2002
Juni P, Egger M. Allocation concealment in clinical trials. JAMA
2002;288(19):2407–9. [: PMID: 12435252]
Kronborg 2002
Kronborg O, Burchardt F, Bülow S, Christiansen J, Gan-
drup P, Harling H, Jakobsen A, Nejer J, FengerC. Guidelines
for diagnosis and treatment of colorektal cancer, 2 (In Dan-
ish). />%20Retningslinier%202002.pdf 2002.
Mealy 1 992
Mealy K, Burke P, HylandJ. Anteriorresection without adefunc tiong
colostomy: questions of safety. Br J Surg 1992;79:305–307.
Moore 1999
Moore J, Hewet P, Penfold JC. Practice parameters for the manage-
ment of colonic cancer I: surgical issues. Recommendations of the
colorectal surgical society of Australia. Aust N Z J Surg 1999;69:415–
421.

Nichols 1 971
Nichols RL, Condon RE. Preoperative preparation of the colon. Surg
Gynecol Obstet 1971;2:323–337.
10Mechanical bowel preparation for elective colorectal surgery (Review)
Copyright © 2008 The Cochrane Collaborat ion. Published by John Wi ley & Sons, Ltd.
O’Dwyer 1989
O’Dwyer PJ, Conway W, McDermott EWM, O’Higgins NJ. Effect
of mechanical bowel preparation on anastomotic integrity following
low anterior resection in dogs. Br J Surg 1989;76:756–8.
Schein 1995
Schein M, Assalia A, Eldar S, Wittmann DH. Is mechanical bowel
preparation necessary before primary colonic anastomosis?. Dis Colon
and Rectum 1995;38:749–754.
Schulz 1996
Schulz KF, Grimes DA, Altman DG , Hayes RJ. Blinding and exclu-
sions after allocation in randomised controlled trials: survery of pub-
lished pa rallel group trials in obstetrics and gynaecology. BMJ 1996;
312:742–744.
SIGN 1997
Scottish Intercollegiate Guidelines Network, Scottish Cancer Ther-
apy Network. Colorectal Cancer, Anational clinical guideline recom-
mended for use in Scotland. National clinical guideline recommended
for use in Scotland. Edinburgh: SIGN, 1997.
Slim 2004
Slim K, Vicaut E, Panis Y, Chipponi J. Meta-analysis of randomized
clinical trials of colorectal surgery with or without mechanical bowel
preparation. Br J Surg 2004;91:1125–1130.
Smith 198 3
Smith SRG, Connolly JC, Gilmore OJA. The effect of faecal loading
on colonic anastomotic healing. Br J Surg 1983;70:49–50.

Thornton 1 997
Thornton FJ, Barbul A. Anastomtic healing in gastrointestinal
surgery. Surg Clin of North Am 1997;3:549–573.
Wille-Jørgensen 1999
Wille-JørgensenP,Kronborg O, SimonN, MunroA, McLeod R, Nel-
son R, editors. Colorectal Cancer Group’s Module of the Cochrane
Database of Systematic Reviews. Cochrane Database of Systematic Re-
views 1999, Issue Issue 4.
References to other published versions of this review
Guenaga 2 002
Guenaga, KF. Preoperative bowel cleansing. Seminars in Colon &
Rectal Surgery 2002;13:53–61.
Wille-Jorgensen 2003
Wille-Jorgensen P, Guenaga KF, Castro AA, Matos D. Clinical
value of preoperative mechanical bowel cleasing in elective colorectal
surgery: a systematic review Disease of Colon and Rectum 2003;46:
1013–1020.
∗
Indicates the major publication for the study
C H A R A C T E R I S T I C S O F S T U D I E S
Characteristics of included studies [ordered by study ID]
Brownson 1992
Methods Randomisation, blinding, follow-up, withdrawal and dropout: no de tails.
Participants Inclusion criteria: patients undergoing elective colorectal surgery. Exclusion criteria: no details. Diseases:
colorectal cancer: 164/179; other: 14/179.
Number of participants: 179. Age: no details. Location of study: Liverpool, UK. Antibiotcs: perioperative
intravenous (no more details).
Interventions A: Mechanical bowel preparation (n=86)
B: No preparation (n=93)
Outcomes Wound infection:

A=5/86, B=7/93
Intra-abdominal sepsis: A=8/86, B=2/93
Anastomic leakage:
A:8/67*, B:1/67*
*Patients whom bowel continuity was restored.
Notes Only conference procreeding - never published as article, results obtained from abstract.
Risk of bias
11Mechanical bowel preparation for elective colorectal surgery (Review)
Copyright © 2008 The Cochrane Collaborat ion. Published by John Wi ley & Sons, Ltd.
Brownson 1992
(Continued )
Item Authors’ judgement Description
Allocation concealment? Unclear B - Unclear
Bucher 2003
Methods Randomisation and blinding: no details
Participants Elective left-sided colorectal surgery
Interventions A: Mechanical Bowel Preparation, 3 litres Polyethylene gl ycol (N=47)
B: No preparation, (N = 46)
Outcomes Anastomotic leakage and wound infection
Notes Conference proceeding.
Risk of bias
Item Authors’ judgement Description
Allocation concealment? Unclear B - Unclear
Burke 1994
Methods Randomisation: no details.
Blinding: single-blind: surgeons was aware of the patient’s bowel preparation.
c) Withdrawal/dropout: 31% (17/186 cases) was withdrawed / no dropout.
d) Follow-up: 07 days after surgery (unclear).
Participants Inclusion criteria: patients admitted for elective colorectal surgery with primary anastomosis.
Exclusion cr iter ia: any patients who could not tolerate the preparation; patients who had had the bowel

’prepared’ for another procedure within previous week.
Diagnoses: 72% colorectal cancer (133/186 cases); 3% inflammatory bowel disease (6/186 cases); 14%
diverticular disease (26/186 cases); 2% other (4/186 cases).
Number: 186 (95 male; 74 female; 17 undetermined).
Age: me an 64 years.
Location of study: Dublin, Ireland.
Time: October, 1988 - September, 1992.
Antibiotics: Ceftriaxone 1 gr and metronidazole 500 mg intravenously starting at induction of anaesthesia.
Metronidazole 500 mg: 8 and 16 h, after initial dosis.
Interventions a) Mechanical bowel preparation group (n = 82): sodium picosulphate 10 mg, the day before surgery (dose
at morning and afternoon).
b) Group B (n= 87): a normal diet and no other bowel preparation.
12Mechanical bowel preparation for elective colorectal surgery (Review)
Copyright © 2008 The Cochrane Collaborat ion. Published by John Wi ley & Sons, Ltd.
Burke 1994
(Continued )
Outcomes a) Death: A=2; B=0.
b) Cardiorespiratory: A=8; B=9.
c) Wound infection: A=4; B=3.
d) Anastomotic dehiscence: A=3; B=4.
e) Reoperation: A=2; B=4.
Notes Representative sample: consecutive patients.
Surgeries procedures that were excluded: patients submitted a Hartman’s resection (5:5); de functioning
colostomy (0:2); abdominal excision of the rectum (1:2); coloanal anastomosis with colostomy (0:1);
colotomy for rectal polyp (1:0).
All surger y was performed by one of two consultant surgeons or a senior registrar.
Excluded patients without anastomosis.
Reccurrence because the leakage.
Left colectomy: A=26; B=28.
Anterior resection: A=56; B=59.

Anastomotic leakage/low anterior resection: A=3/39; B=4/36.
Risk of bias
Item Authors’ judgement Description
Allocation concealment? Unclear B - Unclear
Fa-Si-Oen 2003
Methods Unknown
Participants Colorectal Surgery
Interventions A) Mechanical Bowel Preparation - Polyethylene glycol
B: No cleansing
Outcomes Anastomotic leakage, Wound Infection
Notes Secondary data from another metaanalysis
Risk of bias
Item Authors’ judgement Description
Allocation concealment? Uncl ear B - Unclear
Fillmann 1995
Methods Randomization: no details.
Blinding: double-blind (orange juice for the control group; no details on blinding of the surgeons.
13Mechanical bowel preparation for elective colorectal surgery (Review)
Copyright © 2008 The Cochrane Collaborat ion. Published by John Wi ley & Sons, Ltd.
Fillmann 1995
(Continued )
Withdrawal/dropout: no withdrawal and dropout.
Follow-up: 30 days after surgery.
Participants Inclusion criteria: patients admitted for elective colorectal surgery with primary anastomosis.
Exclusion criteria: no exclusions.
Diseases: colorectal cancer (21:22); diverticular disease (05:06); inflammatory bowel disease (02:02);
Chron disease (01:00); ischaemic colitis (00:01).
Number: 60 (33 male; 27 female).
Age: 31-82 years.
Location: Porto Alegre, RS - Brazil.

Time: 1992-1993.Antibiotics: metronidazole + gentamicin 1 hour before surgery, and during 48 hours.
Interventions Group A -Mechanical bowel preparation (n= 30): 500 ml manitol 20% + 500 ml orange juice.
Group B (n= 30): orange juice.
Outcomes Wound infection: A=1; B=2.
Peritonitis: A=2; B=1.
Extra-abdominal complications (non-infections):-Mechanical obstruction: A =0; B=1 Dehiscence of
wall suture: A=0; B=1. -Pul monary embolism: A=1; B=0.Extra-abdominal complications (infections):-
Pneumonia: A=1; B=1 Urinary infection: A=1; B=2.
Notes The sample size was calculated, but no more details.
Included patients without anastomosis.
Recurrence was not mentioned.
No death reported in this trial.
Risk of bias
Item Authors’ judgement Description
Allocation concealment? Yes A - Adequate
Miettinen 2000
Methods Randomization: sealed envelopes; consecutive adult patients.
Blinding: not described.
Withdrawal/dropout: all the patients completed the study.
Follow-up: 1-2 months after surgery.
Participants Inclusion criteria: all consecutive adults admitted for elective colorectal surgery.
Exclusion criteria: patients who had had bowel preparation for colonoscopy one week before surgery (n=5);
patients who where unable to drink PEG-ELS (n=2); patients not requiring opening of the bowel (n=4);
patient who refused to be randomised (n=1).
Disease: colorectal cancer (134/267); benign tumours (24/267); inflammatory bowel disease (32/267);
diverticular disease (58/267); other (19/267).Number: 267 (130 male; 137 female).Age: 16-97
years.Location: Kuopio + Oulu, Finland.Time: 1994-1996.Antibiotics: ceftriaxone 2 gr + metronidazole 1
gr at the induction of anaesthesia.
Interventions Group A - Mechanical bowel preparation (n=138): Polyethylene glycol electrolyte solution, and no solid
14Mechanical bowel preparation for elective colorectal surgery (Review)

Copyright © 2008 The Cochrane Collaborat ion. Published by John Wi ley & Sons, Ltd.
Miettinen 2000
(Continued )
food on the preoperative day.
Group B (n=129): no preparations and normal diet.
Outcomes Wound infection: A=5; B=3.
Anastomotic leakage: A=5; B=3.
Abdominal abscess: A=3; B=4.
Non-infection postoperative complication: A=11; B=6.
Reoperation: A=4; B=2.
Extra-abdominal infections: A=4; B=2.
Postoperative stay (range/days): A=8; B=8.
Operation time (range/min): A=120; B=110.
Notes Low colonic anastomosis/Leakage: A = 9/3; B = 14/2.
Patients with pre-existing disease: A=48; B=61.
The differences between the two groups were not significant.
All surger y was carried out by a specialist or by a junior surgeon assisted by a specialist.
Excluded patients without anastomosis.
Abdominal abscess: treated conservatively.
Re-operation (total:7/3 ??):
- wound rupture: A=2; B=0;
- perfuration of the gallbladder: A=1; B=0;
- techinical anastomotic failure: A=0; B=1;
- small bowel occlusions: A=1; B=2.
Reoccurrence was because the leakage.
No death in this trial.
Risk of bias
Item Authors’ judgement Description
Allocation concealment? Yes A - Adequate
Santos 1994

Methods Randomisation: patients were allocated by randomised cards.
Blinding: not described.
Withdrawal/dropout: 5% (8/157 cases) was withdrawn / no dropout.
Follow-up: 30 days or until hospital discharge.
Participants Inclusion criteria: Patients admitted for elective colorectal surgery.
Exclusion criteria: patients that had taken antibiotics for at least 15 days before surgery or if there
was evidence of infection or any associated disease requiring antibiotic therapy; and patients that the
mechanical bowel preparation was not feasible.
Group A: 5 patients were excluded: associated infectious disease (2 patients), and failure to achieve full
mechanical bowel preparation (3 patients).
Group B: 3 patients excluded: an intra-abdominal foreign body found during the operation (1 patient),
and urinary tract infection (2 patients).
Diseases: 43% colorectal cancer (68/157); 34% megacolon (53/157); 6% inflammatory bowel disease
15Mechanical bowel preparation for elective colorectal surgery (Review)
Copyright © 2008 The Cochrane Collaborat ion. Published by John Wi ley & Sons, Ltd.
Santos 1994
(Continued )
(9/157); 3% diver ticular disease (5/157); 2% familial adenoma polyposis (3/157); 7% other (11/157).
Number: 157 (72 male; 77 female; 8 undetermined).
Age: 1 - 93 years.
Location: Ribeirão Preto, São Paulo - Brazil.
Time: October, 1991 - December, 1992.
Antibiotics: Cephalothin 2 gr and metronidazole 1 g intravenously at 2 h before induction of anaesthesia.
Cephalothin 1 gr was given 6 and 12 h, and metronidazole 500 mg, 8 and 16 h after the initial dose.
Interventions Group A - Mechanical bowel preparation (n= 72):
LAXATIVE (mineral oil, agar and phenolphthalein) 15 ml taken by mouth three times a day for 5 days
before surgery; mannitol (1 litre as a 10% solution) taken by mouth at the rate of 100 ml per 5 min at
16:00 hours on the day before surgery.
ENEMA (water, 900 ml; glycerin, 100 ml) given once a day for 2 days before surgery.
children : enema of water and glycerin (9:1) twice a day for 2 days before surgery.

Group B (n= 77): a l ow-reside diet and no other mechanical bowel preparation.
Outcomes Wound infection: A=17; B=9. Anastomotic dehiscence: A=7; B=4.
Hospital stay (preoperative): A=2-34; B=0-90. Reoperation: A=4; B=1.
Microbiology (bacteria isolated):
-Bowel content: A=211/62; B=261/72.
-Peritoneal fluid: A=116/62; B=134/72.
-Wounds: A=38/17; B=17/7.
Notes Not described the representative sample.
Patients/Associated medical problems: A=53/75; B=52/78.
Associated medical disease: A=17; B=7.
Patients with complications: A=21 (7+17=?); B=11 (4+9=?).
Most of the patients were operated on by a senior resident (not the consultant).
Included patients without anastomosis.
Reoccurrence was because the leakage.
No death in this trial.
Risk of bias
Item Authors’ judgement Description
Allocation concealment? Yes A - Adequate
Tabusso 2002
Methods Randomisation, blinding, withdrawal and dropout: no details. Follow-up: until hospital discharged (not
described).
Participants Inclusion criteria: pacients with colorectal cancer, submitted an elective colorectal surgery . Exclusion
criteria: no details. Diseases: colorectal cancer. Par ticipantes: 47 (21 male, 26 female). Age: 22 - 87.
Location of study: Lima, Peru. Time: october 1999 - january 2001. Antibiotcs: against anaerobic and Gran
negative bacteria, intravenous, 30 minutes before surgery.
Interventions Group A - Mechanical bowel preparation (n=24): mannitol or polyethylene glycol electrolyte solution +
16Mechanical bowel preparation for elective colorectal surgery (Review)
Copyright © 2008 The Cochrane Collaborat ion. Published by John Wi ley & Sons, Ltd.
Tabusso 2002
(Continued )

liquid diet 48 hours before surgery.
Group B - No mechanical bowel preparation (n=23): liquid diet 48 hours before surgery.
Outcomes Wound infection: A=2; B=0.
Anastomotic leakage: A=5; B=0.
Peritonitis: A=3; B=0.
Notes Length of hospital stay: A=17-19 (14); B=6-15 (11). Analysed only the complications related with the
surgery. Patients without anastomosis (2 patients in A; 3 patients in B).
Risk of bias
Item Authors’ judgement Description
Allocation concealment? Unclear B - Unclear
Zmora 2003
Methods Randomisation: Computer generated.
Follow-up after 30 days
Participants Inclusion criteria:
Pateints admitted for elective colon and rectal surgery
Exclusion criteria:
Not described
Interventions Group A -
Mechanical bowel preparation (n= 187) with polyethyle ne glycol
Group B -
No preparation (n= 193)
Outcomes Overall Infection:
A=19; B=17.
Wound Infection:
A=12; B=11.
Anastomotic leak:
A=7; B=2
Intraabdominal Abscess:
A=2, B=2
Notes All anastomises were “left-sided”

Extra data after stratification has been obtained
Risk of bias
Item Authors’ judgement Description
Allocation concealment? Yes A - Adequate
17Mechanical bowel preparation for elective colorectal surgery (Review)
Copyright © 2008 The Cochrane Collaborat ion. Published by John Wi ley & Sons, Ltd.
Characteristics of excluded studies [ordered by study ID]
Study Reason for exclusion
Dorudi 1990 None
Duthie 1990 The study is a survey.
Without control group.
Hughes 1972 First data as a conference proceedings.
Most of the data are unclear.
The author did not reply to our enquiries, to complete the review.
Irving 1987 Without control group.
Matheson 1978 Testing antimicrobials.
The control group receive elemental diet.
Memon 1997 A retropective and non-randomized study.
18Mechanical bowel preparation for elective colorectal surgery (Review)
Copyright © 2008 The Cochrane Collaborat ion. Published by John Wi ley & Sons, Ltd.
D A T A A N D A N A L Y S E S
Comparison 1. Mechanical bowel preparation versus no preparation
Outcome or subgroup title
No. of
studies
No. of
participants
Statistical method Effect size
1 Anastomosis leakage stratified
for colonic or rectal surgery

Peto Odds Ratio (Peto, Fixed, 95% CI) Subtotals only
1.1 Leakage after low anterior
resection
4 231 Peto Odds Ratio (Peto, Fixed, 95% CI) 1.45 [0.57, 3.67]
1.2 Leakage after colonic
surgery
4 734 Peto Odds Ratio (Peto, Fixed, 95% CI) 1.80 [0.68, 4.75]
2 Overall anastomotic leakage for
colorectal surgery
9 1549 Peto Odds Ratio (Peto, Fixed, 95% CI) 2.03 [1.27, 3.26]
3 Mortality 5 1025 Peto Odds Ratio (Peto, Fixed, 95% CI) 1.72 [0.43, 6.95]
4 Peritonitis 4 553 Peto Odds Ratio (Peto, Fixed, 95% CI) 2.28 [0.99, 5.25]
5 Reoperation 6 785 Peto Odds Ratio (Peto, Fixed, 95% CI) 1.80 [0.81, 3.98]
6 Wound infection 9 1594 Peto Odds Ratio (Peto, Fixed, 95% CI) 1.45 [0.97, 2.18]
7 Infectious extra-abdominal
complications
2 327 Peto Odds Ratio (Peto, Fixed, 95% CI) 0.87 [0.41, 1.87]
8 Non-infectious extra-abdominal
complications
4 872 Peto Odds Ratio (Peto, Fixed, 95% CI) 1.09 [0.75, 1.58]
9 Surgical site infections 2 647 Peto Odds Ratio (Peto, Fixed, 95% CI) 1.20 [0.70, 2.04]
10 Sensitivity analysis 1 - Studies
with dubious randomisation
procedure excluded
Peto Odds Ratio (Peto, Fixed, 95% CI) Subtotals only
10.1 Overall anastomotic
leakage for colorectal surgery
4 856 Peto Odds Ratio (Peto, Fixed, 95% CI) 1.80 [0.90, 3.61]
10.2 Wound infection 4 856 Peto Odds Ratio (Peto, Fixed, 95% CI) 1.50 [0.88, 2.56]
11 Sensitivity analysis 2 - Studies

published as abstract only
excluded
Peto Odds Ratio (Peto, Fixed, 95% CI) Subtotals only
11.1 Anastomotic leakage 6 1072 Peto Odds Ratio (Peto, Fixed, 95% CI) 1.86 [1.03, 3.39]
11.2 Wound infection 6 1072 Peto Odds Ratio (Peto, Fixed, 95% CI) 1.57 [0.96, 2.58]
12 Sensitivity analysis 3 - Studies
including children excluded
Peto Odds Ratio (Peto, Fixed, 95% CI) Subtotals only
12.1 Anastomotic leakage 7 1150 Peto Odds Ratio (Peto, Fixed, 95% CI) 2.38 [1.34, 4.25]
12.2 Wound infection 7 1195 Peto Odds Ratio (Peto, Fixed, 95% CI) 1.26 [0.75, 2.12]
13 Sensitivity analysis 4 - Studies
including patients without
anastomosis excluded
Odds Ratio (M-H, Fixed, 95% CI) Subtotals only
13.1 Anastomosis leakage 5 1043 Odds Ratio (M-H, Fixed, 95% CI) 2.14 [1.09, 4.19]
13.2 Wound infection 5 1088 Odds Ratio (M-H, Fixed, 95% CI) 1.25 [0.72, 2.15]
19Mechanical bowel preparation for elective colorectal surgery (Review)
Copyright © 2008 The Cochrane Collaborat ion. Published by John Wi ley & Sons, Ltd.
Analysis 1.1. Comparison 1 Mechanical bowel preparation versus no preparation, Ou tcome 1 Anastomosis
leakage stratified for colonic or rectal surgery.
Review: Mechanical bowel preparation for elective colorectal surgery
Comparison: 1 Mechanical bowel preparation versus no preparation
Outcome: 1 An astomosis leakage stratified for colonic or rectal su rgery
Study or subgroup Preparation No preparation Peto Odds Ratio Weight Peto Odds Ratio
n/N n/N Peto,Fixed,95% CI Peto,Fixed,95% CI
1 Leakage after low anterior resection
Burke 1994 3/39 4/36 36.0 % 0.67 [ 0.14, 3.15 ]
Miettinen 2000 3/9 2/14
21.9 % 2.92 [ 0.40, 21.25 ]
Santos 1994 2/21 2/29

20.5 % 1.42 [ 0.18, 11.01 ]
Zmora 2003 3/43 1/40
21.6 % 2.62 [ 0.36, 19.34 ]
Subtotal (95% CI) 112 119
100.0 % 1.45 [ 0.57, 3.67 ]
Total events: 11 (Preparati on), 9 (No preparation)
Heterogeneity: Chi
2
= 1.77, df = 3 (P = 0.62); I
2
=0.0%
Test for overall effect: Z = 0.78 (P = 0.43)
2 Leakage after colonic surg e ry
Burke 1994 0/43 0/51 0.0 % Not estimable
Miettinen 2000 2/129 1/115
18.1 % 1.75 [ 0.18, 17.02 ]
Santos 1994 5/51 2/48
40.1 % 2.34 [ 0.51, 10.80 ]
Zmora 2003 4/144 3/153
41.8 % 1.42 [ 0.32, 6.37 ]
Subtotal (95% CI) 367 367
100.0 % 1.80 [ 0.68, 4.75 ]
Total events: 11 (Preparati on), 6 (No preparation)
Heterogeneity: Chi
2
= 0.21, df = 2 (P = 0.90); I
2
=0.0%
Test for overall effect: Z = 1.19 (P = 0.23)
Test for subgroup differences: Chi

2
= 0.10, df = 1 (P = 0.75), I
2
=0.0%
0.01 0.1 1 10 100
Favors preparation Favors control
20Mechanical bowel preparation for elective colorectal surgery (Review)
Copyright © 2008 The Cochrane Collaborat ion. Published by John Wi ley & Sons, Ltd.
Review: Mechanical bowel preparation for elective colorectal surgery
Comparison: 1 Mechanical bowel preparation versus no preparation
Outcome: 1 An astomosis leakage stratified for colonic or rectal su rgery
Study or subgroup Preparation No preparation Peto Odds Ratio Peto Odds Ratio
n/N n/N Peto,Fixed,95% CI Peto,Fixed,95% CI
1 Leakage after low anterior resection
Burke 1994 3/39 4/36
0.67 [ 0.14, 3.15 ]
Miettinen 2000 3/9 2/14
2.92 [ 0.40, 21.25 ]
Santos 1994 2/21 2/29
1.42 [ 0.18, 11.01 ]
Zmora 2003 3/43 1/40
2.62 [ 0.36, 19.34 ]
Subtotal (95% CI) 112 119
1.45 [ 0.57, 3.67 ]
Total events: 11 (Preparati on), 9 (No preparation)
Heterogeneity: Chi
2
= 1.77, df = 3 (P = 0.62); I
2
=0.0%

Test for overall effect: Z = 0.78 (P = 0.43)
0.01 0.1 1 10 100
Favors preparation Favors control
Review: Mechanical bowel preparation for elective colorectal surgery
Comparison: 1 Mechanical bowel preparation versus no preparation
Outcome: 1 An astomosis leakage stratified for colonic or rectal su rgery
Study or subgroup Preparation No preparation Peto Odds Ratio Peto Odds Ratio
n/N n/N Peto,Fixed,95% CI Peto,Fixed,95% CI
2 Leakage after colonic surg e ry
Burke 1994 0/43 0/51 Not estimable
Miettinen 2000 2/129 1/115
1.75 [ 0.18, 17.02 ]
Santos 1994 5/51 2/48
2.34 [ 0.51, 10.80 ]
Zmora 2003 4/144 3/153
1.42 [ 0.32, 6.37 ]
Subtotal (95% CI) 367 367
1.80 [ 0.68, 4.75 ]
Total events: 11 (Preparati on), 6 (No preparation)
Heterogeneity: Chi
2
= 0.21, df = 2 (P = 0.90); I
2
=0.0%
Test for overall effect: Z = 1.19 (P = 0.23)
0.01 0.1 1 10 100
Favors preparation Favors control
21Mechanical bowel preparation for elective colorectal surgery (Review)
Copyright © 2008 The Cochrane Collaborat ion. Published by John Wi ley & Sons, Ltd.
Analysis 1.2. Comparison 1 Mechanical bowel preparation versus no preparation, Outcome 2 Overall

anastomotic leakage for colorectal surgery.
Review: Mechanical bowel preparation for elective colorectal surgery
Comparison: 1 Mechanical bowel preparation versus no preparation
Outcome: 2 Overall anastomotic leakage for colorectal surgery
Study or subgroup Preparation No preparation Peto Odds Ratio Weight Peto Odds Ratio
n/N n/N Peto,Fixed,95% CI Peto,Fixed,95% CI
Brownson 1992 8/67 1/67 12.3 % 5.23 [ 1.36, 20.14 ]
Bucher 2003 4/47 1/46
7.0 % 3.43 [ 0.57, 20.59 ]
Burke 1994 3/82 4/87
9.8 % 0.79 [ 0.17, 3.58 ]
Fa-Si-Oen 2003 7/125 6/125
18.0 % 1.18 [ 0.39, 3.58 ]
Fillmann 1995 2/30 1/30
4.2 % 1.99 [ 0.20, 19.94 ]
Miettinen 2000 5/138 3/129
11.3 % 1.56 [ 0.38, 6.36 ]
Santos 1994 7/72 4/77
14.9 % 1.93 [ 0.57, 6.57 ]
Tabusso 2002 5/24 0/23
6.7 % 8.54 [ 1.36, 53.51 ]
Zmora 2003 7/187 4/193
15.6 % 1.81 [ 0.55, 5.99 ]
Total (95% CI) 772 777
100.0 % 2.03 [ 1.27, 3.26 ]
Total events: 48 (Preparati on), 24 (No p reparation)
Heterogeneity: Chi
2
= 7.18, df = 8 (P = 0.52); I
2

=0.0%
Test for overall effect: Z = 2.94 (P = 0.0033)
0.01 0.1 1 10 100
Favors preparation Favors control
22Mechanical bowel preparation for elective colorectal surgery (Review)
Copyright © 2008 The Cochrane Collaborat ion. Published by John Wi ley & Sons, Ltd.
Analysis 1.3. Comparison 1 Mechanical bowel preparation versus no preparation, Ou tcome 3 Mortality.
Review: Mechanical bowel preparation for elective colorectal surgery
Comparison: 1 Mechanical bowel preparation versus no preparation
Outcome: 3 Mortality
Study or subgroup Preparation No preparation Peto Odds Ratio Weight Peto Odds Ratio
n/N n/N Peto,Fixed,95% CI Peto,Fixed,95% CI
Burke 1994 2/82 0/87 25.1 % 7.95 [ 0.49, 128.33 ]
Fillmann 1995 0/30 0/30 0.0 % Not estimable
Miettinen 2000 0/138 0/129 0.0 % Not estimable
Santos 1994 0/72 0/77 0.0 % Not estimable
Zmora 2003 3/187 3/193 74.9 % 1.03 [ 0.21, 5.17 ]
Total (95% CI) 509 516
100.0 % 1.72 [ 0.43, 6.95 ]
Total events: 5 (Preparation), 3 (No prepara tion)
Heterogeneity: Chi
2
= 1.55, df = 1 (P = 0.21); I
2
=35%
Test for overall effect: Z = 0.77 (P = 0.44)
0.01 0.1 1 10 100
Favours preparation Favours control
Analysis 1.4. Compariso n 1 Mechanical bowel preparation versus no p reparation, Outcome 4 Peritonitis.
Review: Mechanical bowel preparation for elective colorectal surgery

Comparison: 1 Mechanical bowel preparation versus no preparation
Outcome: 4 Peritonitis
Study or subgroup Preparation No preparation Peto Odds Ratio Weight Peto Odds Ratio
n/N n/N Peto,Fixed,95% CI Peto,Fixed,95% CI
Brownson 1992 8/86 2/93 42.9 % 3.85 [ 1.08, 13.76 ]
Fillmann 1995 2/30 1/30
13.1 % 1.99 [ 0.20, 19.94 ]
Miettinen 2000 3/138 4/129
31.0 % 0.70 [ 0.16, 3.12 ]
Tabusso 2002 3/24 0/23
13.0 % 7.75 [ 0.77, 78.41 ]
Total (95% CI) 278 275
100.0 % 2.28 [ 0.99, 5.25 ]
Total events: 16 (Preparati on), 7 (No preparation)
Heterogeneity: Chi
2
= 4.14, df = 3 (P = 0.25); I
2
=28%
Test for overall effect: Z = 1.93 (P = 0.053)
0.01 0.1 1 10 100
Favors preparation Favors control
23Mechanical bowel preparation for elective colorectal surgery (Review)
Copyright © 2008 The Cochrane Collaborat ion. Published by John Wi ley & Sons, Ltd.