Accuracy of ultrasonography for the diagnosis of intussusception in infants in Vietnam

Pediatr Radiol (2007) 37:195–199
DOI 10.1007/s00247-006-0381-1

ORIGINAL ARTICLE

Accuracy of ultrasonography for the diagnosis
of intussusception in infants in Vietnam
Frances A. Justice & Margaret de Campo &
Nguyen Thanh Liem & Tran Ngoc Son &
Tran Phan Ninh & Julie E. Bines

Received: 6 September 2006 / Revised: 15 November 2006 / Accepted: 16 November 2006 / Published online: 20 December 2006
# Springer-Verlag 2006

Abstract
Background Intussusception (IS) is the most common
cause of acute bowel obstruction in infants and young
children. Ultrasonography is being increasingly used as the
primary investigation for the diagnosis of IS and to guide
air or hydrostatic enema reduction. However the accuracy
of ultrasonography outside tertiary care settings in developed countries has not been assessed, particularly in Asia
where the incidence of IS based on sonographic diagnosis
has been reported as the highest in the world.
Objective The aim of this study was to evaluate the accuracy
of ultrasonography in the diagnosis of acute IS in infants less
than 2 years of age in a paediatric hospital in Vietnam.
F. A. Justice : J. E. Bines
Murdoch Children’s Research Institute,
Melbourne, Australia
J. E. Bines (*)
Department of Gastroenterology and Clinical Nutrition,

Royal Children’s Hospital,
Parkville, 3052 Victoria, Australia
e-mail:
J. E. Bines
Department of Paediatrics, University of Melbourne,
Melbourne, Australia
M. de Campo
Department of Diagnostic Imaging,
Princess Margaret Hospital for Children,
Perth, Australia
N. T. Liem : T. N. Son
Department of Surgery, National Hospital of Paediatrics,
Hanoi, Vietnam
T. P. Ninh
Department of Imaging, National Hospital of Paediatrics,
Hanoi, Vietnam

Materials and methods A prospective study was conducted
at the National Hospital for Paediatrics, Hanoi, Vietnam, over
a 14-month period recruiting patients <2 years of age with IS.
Abdominal ultrasonography was performed on each patient
and the accuracy of the diagnosis was evaluated against the
final diagnosis provided by air enema and/or surgery.
Results A total of 640 infants <2 years of age presented
with clinical symptoms and signs of IS. The diagnosis was
confirmed in 533 patients via air enema or surgery.
Abdominal ultrasonography was 97.5% (466/478) sensitive
and 99% (106/107) specific in the detection of IS.
Conclusion Ultrasonography is an accurate, safe and
valuable clinical tool in the diagnosis of IS. The use of

ultrasonography as a primary investigation for patients with
suspected IS prevents unnecessary radiological or surgical
procedures being performed, and reduces radiation exposure while maintaining a high level of diagnostic accuracy.
These results validate the use of ultrasonography for the
diagnosis of IS in a developing country setting.
Keywords Intussusception . Ultrasonography .
Intestinal obstruction . Radiography . Children

Introduction
Intussusception (IS) is the most common cause of acute
bowel obstruction in infants and young children and can
potentially be fatal if not diagnosed and treated promptly.
Barium enema has been used for diagnosis and reduction of
IS for over 30 years [1], with the air enema introduced in
the late 1980s as a safer technique with higher reduction
rates [2–5]. More recently ultrasonography has been used
as the primary diagnostic procedure and to guide enema
reduction in patients with IS particularly in Asia and


196

Europe [6–9]. Ultrasonography is a dynamic procedure,
with a high level of accuracy in the diagnosis of IS when
characteristic features such as a target sign, donut or
pseudokidney image are observed [10]. A negative sonographic diagnosis of IS avoids an unnecessary diagnostic air
or liquid enema.
The accuracy of ultrasonography in the diagnosis of IS
in health-care settings may vary with the quality of
sonographic equipment and the training and experience of

the operators [7–9, 11–13]. Some studies have therefore
emphasized caution in the use of ultrasonography alone to
diagnose IS, recommending its use for low-risk patients
who are less likely to require enema reduction [11, 14, 15].
In health-care settings of many developing countries,
ultrasonography facilities are available and have become
the primary diagnostic procedure for IS, particularly in
China and Vietnam [6, 7, 16]. However, interpretation of
reports of high rates of IS in China and Vietnam has been
guarded when studies have been based on sonographic
diagnosis alone [17, 18]. The aim of this study was to
evaluate the accuracy of ultrasonography in the diagnosis of
acute IS in infants less than 2 years of age in a paediatric
hospital in Vietnam.

Materials and methods
A prospective study was conducted at the National Hospital
for Paediatrics (NHP), Hanoi, Vietnam, over a 14-month
period from 1 November 2002 to 31 December 2003. The
study was approved by the Ethics Committee of the
Ministry of Health, Vietnam.
Patients were eligible for inclusion in the study if they
were less than 2 years of age and presented to the
emergency department at NHP with symptoms and signs
consistent with a clinical diagnosis of IS, including
vomiting, abdominal pain and/or distension, rectal bleeding, pallor or lethargy. The clinical assessment of these
patients indicated the need for further information to
diagnose or exclude IS. Patients with recurrent and nonidiopathic IS were excluded from the final data analysis.
Study patients underwent abdominal ultrasonography performed using a Vingmed scanner (Oslo, Norway) and a
linear 5-MHz transducer. The final diagnosis of IS was

confirmed by air enema or surgery.
Ultrasonographic images taken at the time of diagnosis
and radiographs taken before, during and after air enema
reduction were obtained. Ultrasonographic images were
retrospectively assessed by an independent blinded radiologist to validate the diagnosis of IS and to determine the
sensitivity and specificity of the sonographic diagnosis of
IS. Air enema films were separately and independently
assessed by the same blinded radiologist to validate the

Pediatr Radiol (2007) 37:195–199

diagnosis of IS at air enema. Results of air enema
reductions and surgical procedures were documented.

Results
During the study period, 640 infants (412 male, 228
female) presented with suspected acute IS. The diagnosis
of IS was established in 533 patients (83%) by air enema
(n=513) and/or surgery (n=65). Independent validation by
a blinded radiologist was possible in 467 of the 513 patients
undergoing an air enema examination and in whom
radiographic films were available for retrospective review.
The diagnosis of IS was independently confirmed in 409 of
the 467 patients (87%). IS could not be confirmed in 36 of the
467 patients (8%) as the IS had reduced during air enema
before a radiograph could be taken. The remaining 22 patients
(5%) were considered as “likely” to have IS but the diagnosis
could not be confirmed on the air enema films available for
review.
The median age of the 533 patients diagnosed with IS

was 9.3 months (range 3–24 months) and there was a
predominance of male infants (65%). The diagnosis of IS
was established within 24 h of the onset of symptoms in
most patients (383 of 500 patients, 77%; median 12 h,
interquartile range 7–24 h).
To assess the accuracy of ultrasonography in the
diagnosis of IS, an abdominal sonographic examination
was performed in 478 of 533 patients (90%) prior to
performing an air enema and/or surgery. An IS was

Fig. 1 Transverse upper abdominal US image demonstrates an
ileocolic IS with pseudokidney appearance in the hepatic flexure
region, anteromedial to the right kidney


Pediatr Radiol (2007) 37:195–199

197

Table 1 Retrospective validation by an independent blinded radiologist of the diagnosis of IS in 447 US images available from among
478 images acquired from 533 patients diagnosed with IS at the NHP,
Vietnam. Of the 478 US images acquired, 466 (97%) were considered
positive for IS
Diagnosis of IS

Number of images

Percent of available images

Positive

Possible
Not confirmed

417
22
8

93
5
2

identified on ultrasonography in 466 of the 478 patients
(Fig. 1), resulting in a sensitivity of ultrasonography in the
diagnosis of IS of 97.5%. Of the 12 patients negative on
ultrasonography, an IS was identified on air enema (n=4)
or surgery (n=8). The sonographic diagnosis was confirmed retrospectively by an independent blinded radiologist in 417 of 447 patients (93%) with images available for
assessment (Table 1).
The remaining 107 of 640 patients presenting with
clinical symptoms and signs consistent with a diagnosis of
IS had the diagnosis excluded by air enema (n=6) or
subsequent clinical review (n=101). None of these patients
re-presented to the hospital with an IS at a later date.
Abdominal sonography was negative for IS in 106 of the
107 patients, giving a specificity and negative predictive
value of 99% (106 of 107) and 90% (106 of 118),
respectively (Table 2).
Reduction of IS by air enema was successful in 468 of
504 attempts (93%). The median number of attempts
required for successful air enema reduction was 1 (range
1–12 attempts) at a median pressure of 90 mmHg (range

70–130 mmHg) (Table 3). Surgical reduction was required
in 12% of all patients. Only 2% of patients (12 of 533)
required intestinal resection as part of IS reduction. These
patients comprised eight with failed air enema reduction

Table 3 Treatment of intussusception in 533 patients
Treatment
Air enema (n=513)

Surgery (n=65)

No. of patients
Performed
Reduction attempted
Reduction successful
Number of attempts
1
2
3
4–6
7–12
Failed enema reduction
Primary surgery
Intestinal resection

513
504
468
292
133

46
30
12
45
20
12

and four treated surgically as a primary intervention. The
median length of resection was 20 cm (range 10–30 cm).
No mortality was observed.

Discussion
The reliability of ultrasonography as a diagnostic tool for
detection of IS has been widely debated. We have shown in
this large-scale prospective study that ultrasonography is
sensitive (97.5%) and specific (99%) in the diagnosis of
acute IS in children aged <2 years in a developing country
despite the use of equipment older than is generally
available in developed countries (Table 2). The results of
this study suggest that the high rates of IS in Vietnam
previously reported [16, 19] are accurate and that despite
the reduced availability of state-of-the-art sonographic
equipment in Vietnam the high number of patients presenting to hospital with IS ensures that staff have extensive
clinical and diagnostic experience and expertise.

Table 2 Sensitivity and specificity of ultrasound use to diagnose IS worldwide
Country

Reference

Year of publication

Sensitivity

Specificity

France
China
Taiwan
Canada
Korea
USA
The Netherlands
Korea
Australia
Canada
Vietnam

23
7
25
13
26
14
8
22
27
15
This study

1987
1988
1989
1992
1992
1992
1994
1994
1996
1998
2006

100% (145/145)
100% (377/377)
100% (48/48)
100% (34/34)
100% (75/75)
100% (20/20)
98.5% (128/130)
100% (65/65)
100% (7/7)
96.6% (87/90)
97.5% (466/478)

100% (281/281)

88% (43/49)
100% (7/7)
93% (42/45)
100% (33/33)

100% (112/112)
95% (41/43)
95.4% (148/155)
99% (106/107)

Positive
predictive value

Negative predictive
value

100% (43/43)
87% (20/23)
100% (128/128)

100% (42/42)
94% (33/35)

78% (7/9)
92.6% (87/94)
99.7% (466/467)

100% (41/41)
98% (148/151)
90% (106/118)


198

Although some reports have expressed concern with the

use of ultrasonography in the hands of inexperienced
operators potentially resulting in false-negative diagnoses
[15], others such as Shanbhogue et al. [8] suggest a few
months training is sufficient for high accuracy investigation
of clinically suspected IS [11–13]. In our study, the
operators in Hanoi were trained paediatric ultrasonographers with more than 8 years’ experience and an estimated
workload of 500 IS cases per year. Their US diagnoses
were retrospectively confirmed in 93% of cases by a
blinded paediatric radiologist. We acknowledge that a
retrospective review of static images by a blinded radiologist may be a potential weakness of this study; however, it
is likely that this would underestimate rather than overestimate the accuracy of the diagnosis.
Absence of radiation, non-invasiveness and rapid nature
of ultrasonography have major clinical and technical
advantages. Of the patients who were negative for IS on
ultrasonography in this study, 94% did not proceed to air
enema, avoiding exposure to radiation and the discomfort
of undergoing an enema. Ultrasonography also enables
follow-up screening to confirm reduction or investigate
persisting symptoms [12]. Transient IS or spontaneous
reduction can be observed using ultrasonography, obviating
the need for enema reduction [20, 21]. Additionally, colour
Doppler US has been reported to aid prediction of
reducibility of IS by enema [22]. Pracros et al. [23] have
also shown that ultrasonography assists the diagnosis of
other conditions including urinary tract pathology, ovarian
disorders, necrotizing enterocolitis, cyst of the common bile
duct and small bowel volvulus.
Due to the rare association between a rotavirus vaccine
(Rotashield®) and IS, the World Health Organization has
recommended that countries planning to introduce a

rotavirus vaccine should develop post-marketing surveillance systems to promptly identify and manage cases of IS
[24]. Many developing countries rely on ultrasonography
for the diagnosis of IS. This study confirms the accuracy
and reliability of ultrasonography for the diagnosis of acute
IS in infants in Vietnam.

Conclusion
Ultrasonography is an accurate, safe and valuable clinical
tool in the diagnosis of acute IS in infants in Vietnam. The
use of ultrasonography as a primary investigation for
patients with suspected IS prevented unnecessary radiological or surgical procedures being performed, and reduced
exposure to radiation while maintaining a high level of
accuracy in diagnosis. Ultrasonography has been validated
as a valuable tool for the diagnosis of IS as Vietnam
prepares for the introduction of rotavirus vaccines.

Pediatr Radiol (2007) 37:195–199
Acknowledgements This project was made possible by a grant from
the World Health Organization. We thank the infants and their families
for their participation in this study. We would also like to acknowledge
the staff from the Imaging, Surgical and Emergency Departments at
the National Hospital of Paediatrics, Hanoi, for conducting this study
and the staff of the Royal Children’s Hospital International (RCHI) for
their assistance.

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