NONVERTEX PRESENTATIONS, SHOULDER DYSTOCIA, AND CORD ACCIDENTS pot

403
BREECH PRESENTATION
DEFINITIONS, ASSOCIATIONS,
INCIDENCES, AND IMPORTANCE
Breech is a longitudinal presentation in which the cephalic pole oc-
cupies the fundus and the caudal (podalic) pole lies in the lower
segment of the uterine cavity or within the birth canal. Overall
breech presentation occurs in 3%–4% of singleton pregnancies com-
mencing labor, but has a much higher incidence in multiple gesta-
tions (e.g., ϳ25% of first twins and ϳ50% of second twins are
breech). The incidence rises further in higher order multiple preg-
nancies. Other associations with breech presentation include: ear-
lier gestations (35% at Ͻ28 weeks, 25% at 28–32 weeks, 20% at
32–34 weeks, 8% at 34–35 weeks, 2%–3% at Ͼ36 weeks), a prior
breech (over 4-fold increase after one and up to 30-fold after three),
placental placement (i.e., placenta previa), oligohydramnios, fetal
congenital anomalies (e.g., hydrocephalus), pelvic tumors imping-
ing on the uterus or birth canal (e.g., leiomyomata), and uterine
anomalies (e.g., bicornuate, septate uterus).
As presentations are thought to be a matter of fetal–uterine ac-
commodation, breech presentation may be caused by any aberration
of this adaptive process or of the fetal attitude. Thus, breech presen-
tation is not a disease or an abnormality. However, breech presenta-
tion may be an important sign of congenital fetal compromise. For
example, breech presentation is increased with chromosomal anom-
alies (e.g., trisomies 18 and 21), neuromuscular abnormalities (e.g.,
familial dysautonomia), and skeletal malformations (e.g., spina bifida,
meningomyelocele). The incidence of major congenital anomalies
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NONVERTEX PRESENTATIONS,
SHOULDER DYSTOCIA, AND

CORD ACCIDENTS
CHAPTER
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BENSON & PERNOLL’S
404 HANDBOOK OF OBSTETRICS AND GYNECOLOGY
(e.g., anaencephaly, hydrocephaly) in breech presentations is more
than double (ϳ6%) that found in vertex. Additionally, delivery of the
breech fetus imposes perinatal risks of birth anoxia and birth trauma
as well as maternal risks of traumatic delivery, or cesarean section.
There are three types of breech presentation (Fig. 14-1): frank
(legs flexed at the hip and extended at the knee), complete (legs
flexed at the hip and flexed at the knee), and footling (legs extended
at the hip and extended at the knee). The amount of both hip and
knee extension in footling breech is variable and may involve one
FIGURE 14-1. The three types of breech presentation.
(single footling) or both (double footling) feet as the presenting part.
The incidence of frank breech increases as size increases (40%
Ͻ2500 g, 65% over 2500 g), whereas complete breech represents
ϳ10% at all sizes and footling breech decreases in relation to size
(50% Ͻ2500 g, 25% Ͼ2500 g). In breech presentations (all three
types), the fetal reference point to describe position and station is
the sacrum. Knowledge of the type of breech presentation is es-
sential to management.
DIAGNOSIS
Physical examination is generally the first clue to breech presenta-
tions. Leopold’s maneuvers discover the softer and less well-defined
breech above the pelvic inlet and the firm, well-defined head in the
uterine fundus. The fetal heart (heard best over the back) is found
higher on the maternal abdomen. Vaginal examination (with cervical
dilatation) reveals the softer and irregular breech presentation, a

foot, or feet as opposed to the usually encountered firm, smooth,
rounded cephalic presentation with readily identified sutures. The
diagnosis is usually confirmed by sonography.
Sonography is also useful to determine multiple gestation, the
type of breech, attitude, size (and gestational age), location of the
placenta, and amniotic fluid volume. Given the incidence of con-
genital anomalies (Ͼ6%) associated with breech presentation, an
anatomic survey is also helpful. If the sonography has been ac-
complished at some time prior to labor, it is useful to repeat the ul-
trasound at the onset or early in labor to confirm fetal presentation,
head position, and to estimate fetal size. Radiography is rarely nec-
essary.
MANAGEMENT
PRENATAL
Confirmation, Follow-up, and Counseling
Given current utilization of sonography during pregnancy, breech
presentations are usually detected in the second trimester. However,
some breech presentations remain undetected prior to the onset of
labor. A recent report from a large managed care program indicated
that ϳ21% of term breeches were not detected before the onset of
labor and an additional 15% not detected until after 38 weeks of
gestation. On those that are detected earlier, follow up sonography
(often ϳ32 weeks and ϳ36 weeks) is useful to ascertain if the usual
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course of spontaneous version to vertex occurs, to determine fetal
size and attitude, and to screen for fetal defects. Breech patients are

considered at risk and their care plans are customarily individual-
ized and more rigorous than vertex, low-risk patients.
When breech presentation persists, parental involvement is en-
couraged. This usually involves dissemination of information,
counseling concerning the presentation, detailing available man-
agement options, and discussion of the parent’s concerns and ques-
tions. The goal of this counseling is to formulate a plan for deliv-
ery that meets the parents’ desires, can be executed by the health
care provider(s), and affords maximal safety for both mother and
child.
Patients with breech presentations are warned to come to the
hospital as soon as labor begins or spontaneous rupture of mem-
branes occurs. The latter is particularly important because of the in-
creased incidence of cord prolapse. As noted previously, admission
sonography is necessary.
External Cephalic Version
External cephalic version (ECV) is the term describing maneuvers
performed through the maternal abdominal wall attempting to con-
vert the presentation from breech to vertex (Fig. 14-2). Antenatally,
ECV is limited to singleton gestations and is usually performed af-
ter the 36th week, but prior to the onset of labor. Although ECV
has been performed as early as the 28th week of gestation, early at-
tempts are currently less favored because of a high recurrence to
breech and to avoid preterm delivery if complications occur.
ECV is more successful in: multigravidas, pregnancies with suf-
ficient amniotic fluid, and in unengaged complete and footling
breech presentations. ECV is contraindicated by: prior uterine sur-
gery (myomectomy, cesarean section or metroplasty), suspected or
documented congenital malformations, indications of fetal com-
promise (e.g., intrauterine growth retardation, abnormal biophysi-

cal testing), placenta previa, anterior placentation (i.e., placenta be-
tween the fetus and the abdominal wall), abruptio placenta,
premature rupture of the membranes, marked oligohydramnios, and
engagement of the presenting part. Relative contraindications in-
clude those conditions limiting the use of tocolytic agents (mater-
nal cardiac disease, diabetes mellitus, or thyroid disorders) and frank
breech (the lower extremities act as a splint, preventing flexion).
ECV should only be performed in a facility with proper equip-
ment and staffing for emergency cesarean. One commonly used rou-
tine follows.
Obtain informed consent. The patient should inform the opera-
tor if pain occurs or if the maneuvers seem too forceful.
Sonographically verify presentation, flexion of the fetal head,
appropriateness of size, and adequacy of amniotic fluid. If not
previously performed, rule out fetal congenital anomalies and
uterine abnormalities.
A nonstress test is conducted and must be reactive to proceed.
A Kleihauer-Betke test is drawn to rule out fetomaternal hem-
orrhage.
Determine if the uterus is sufficiently relaxed to allow the
procedure without tocolysis. Although uterine tone may be the
most important predictor of success when selecting candidates for
ECV, other useful criteria are uterine irritability and contractions.
If further relaxation is necessary administer ritodrine hy-
drochloride, 0.15 mg/min IV for 15 min. Analgesics and anes-
thetics are not generally used.
Using both hands on the patient’s abdomen, gently “disengage”
the fetal lower pole by moving it toward the fundus as well as
laterally toward the fetal back. Simultaneously, pressure is ex-
erted on the fetal head downward and contralateral to the

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NONVERTEX PRESENTATIONS, SHOULDER DYSTOCIA
407
FIGURE 14-2. External cephalic version demonstrating an alternative to
the successful “forward roll.”
BENSON & PERNOLL’S
408 HANDBOOK OF OBSTETRICS AND GYNECOLOGY
direction of the lower pole. In sum, this is positioning the fetus
in a forward roll. If that is unsuccessful, a back flip may be
attempted. If unsuccessful, the ECV may be reattempted at a
later time.
Sonographic or electronic fetal monitoring is used during and
after to monitor fetal well-being and ascertain the success of
ECV.
Following ECV, the nonstress test and Kleihauer-Betke tests are
repeated. Signs of fetal compromise (e.g., electronic fetal mon-
itoring criteria, fetomaternal hemorrhage) are treated accord-
ingly (usually immediate cesarean) and if the Kleihauer-Betke
is positive and the mother is Rh-negative, Rh immune globulin
is given to prevent sensititization.
In the absence of worrisome findings in this screening, the spon-
taneous onset of labor is routinely monitored by outpatient care.
The overall success of ECV is reported to be as high as 66%,
with 33%–50% success for nullipara and 45%–75% success for
multiparas. Although successful ECVs may return to breech prior
to delivery, this generally happens in Ͻ10%. Women with suc-
cessful ECV have approximately the same cesarean rate as those
with primary cephalic presentations. Although ECV may afford the
individual patient the opportunity for a cephalic vaginal delivery, it
would reduce overall cesarean rates by only ϳ1% if universally ap-

plied. Complications of ECV also include: intrauterine fetal demise
secondary to umbilical cord entanglement (Ͻ1%), emergency ce-
sarean (Ͻ1%), abruptio placenta, premature rupture of membranes,
preterm labor, umbilical cord prolapse, fetomaternal hemorrhage,
and uterine rupture.
Planned Vaginal Delivery
Health providers contemplating a vaginal breech delivery must be
both trained as well as experienced in the process and procedure.
Adequate support must be available, including: an experienced
obstetrician to assist with delivery, and anesthesiologist and a
pediatrician capable of providing total resuscitation and care of the
newborn. Anesthesia is usually kept to a minimum, although
epidural anesthesia has proven useful. The additional support
personnel (e.g., nursing, respiratory therapy) and facilities must be
prepared to deal with these patients as part of a comprehensive team.
Factors predisposing to fetal injury during labor and delivery
of a breech presentation include: greater incidence of umbilical cord
prolapse, a higher incidence of cord compromise during labor, in-
creased incidence of placental separation, entrapment of the head
by the cervix, injury to the head and neck by more rapid descent
through the birth canal, injury of the head and neck by the mode of
delivery, and a greater chance of injury to the upper extremities.
Thus, attempting vaginal delivery is usually reserved for patients
meeting rather stringent criteria (Table 14-1).
Using such criteria, 10%–15% of all candidates will meet the
criteria. Of those, ϳ70% will deliver vaginally, but nulliparas are
only ϳ50% likely to succeed whereas ϳ75% of multiparas will be
delivered vaginally. The most common indications for cesarean sec-
tion are labor disorders or nonreassuring fetal heart rate patterns.
Recently, induction of labor in patients with a breech presentation

and an unripe cervix using proglandin ripening has been reported
to be efficacious (vaginal delivery of ϳ50%) and safe. The use of
oxytocin for labor abnormalities remains controversial.
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NONVERTEX PRESENTATIONS, SHOULDER DYSTOCIA
409
TABLE 14-1
CRITERIA FOR ATTEMPTING VAGINAL DELIVERY
Fetal criteria
Frank breech presentations (although selected cases of
complete or footling breech are considered in certain
centers)
Gestational age of Ն34 weeks
Estimated fetal weight of 2000–3500 g
Flexed fetal head
Maternal criteria
Informed consent
Adequate maternal pelvis (many authorities believe this
should be obtained by x-ray pelvimetry, whereas
others believe a clinical evaluation is sufficient; data
are inadequate to indicate this improves perinatal
outcomes)
Absence of maternal contraindications to labor
Absence of maternal or fetal indications for cesarean
section
Special circumstances
Presentation in advanced labor with no fetal or maternal
compromise; a controlled vaginal delivery may be
safer in these circumstances than a hastily executed
cesarean section

Previable fetus
Lethal fetal congenital anomalies
BENSON & PERNOLL’S
410 HANDBOOK OF OBSTETRICS AND GYNECOLOGY
Umbilical cord blood acid–base values for uncomplicated, term,
vaginal breech deliveries differ significantly from those of uncom-
plicated cephalic vaginal delivery. The differences suggest a greater
degree of acute cord compression with vaginal breech delivery.
This suggestion is furthered by breech vaginal deliveries (com-
pared to elective cesarean) having a greater risk of low Apgar scores
(as high as 15-fold more). Additionally, there are significantly more
neonatal intensive care admissions for vaginal breech deliveries
(Ͼ1.5-fold).
Planned Cesarean Section Delivery
Given the risks of cord prolapse with rupture of the membranes, as
well as the risks of early labor, most planned cesarean deliveries
are electively scheduled at Ն38th week. One set of criteria for these
cases follows (Table 14-2).
Singleton breech cesarean deliveries have lower birth weight-
specific neonatal morbidity and mortality compared to vaginal
births. Approximately 30% of patients anticipating a vaginal deliv-
ery will have cesarean section delivery for signs of fetal compro-
mise or abnormalities of labor.
INTRAPARTUM
TABLE 14-2
CRITERIA FOR PLANNED CESAREAN
SECTION DELIVERY
Fetal criteria
Estimate fetal weight of Ͼ3500 g
Deflexed fetal head

Prolonged rupture of membranes
Unengaged presenting part
Premature fetus (gestation of 25–34 weeks)
Most complete or footling breech presentations Ͼ25
weeks without detectable lethal congenital anomalies
Variable heart rate deceleration on electronic monitoring
Maternal criteria
Informed consent
Contracted or borderline pelvic capacity
Elderly primigravida
Infertility problems or poor obstetric history
Dysfunctional labor
As noted previously, patients with breech presentations should come
to the hospital as soon as possible when rupture of the membranes
or labor occurs. A repeat sonography is accomplished with specific
attention to position, attitude, and location of fetal extremities. A
full history and physical examination are accomplished. Pelvic ex-
amination is conducted, with specific attention to station and
whether cord is presenting or palpable. Fetal monitoring is per-
formed and fetal well being assessed. Reappraisal of the mode of
delivery is performed. The preparations necessary for delivery are
conducted (see above).
If a vaginal delivery is anticipated, the screening for fetopelvic
disproportion is reassessed and the necessary preparations for vagi-
nal and cesarean delivery are conducted. Continuous monitoring is
performed to screen for fetal compromise. Labor’s progress is care-
fully evaluated by monitoring dilatation and descent of the pre-
senting part. Artificial rupture of the membranes is avoided until
the presenting part is well applied. At the time of membrane rup-
ture, the patient is examined vaginally to check for potential cord

prolapse. As little analgesia and anesthesia as possible is used, with
epidural anesthesia being the choice should mild analgesia and lo-
cal anesthesia not be adequate. Abnormalities of labor are regarded
for their potential indication of cesarean section necessity. The sec-
ond stage of labor is interfered with as little as possible.
DELIVERY
Cesarean Section
The cesarean incision is chosen to be as atraumatic to the fetus as
possible. A vertical incision in the lower uterine segment (which
frequently extends into the lower fundus) is chosen when the pre-
senting part is higher in the uterus, if there is an indication that the
fetus will require more room for delivery, and for many premature
deliveries. A transverse lower uterine segment incision is performed
when the lower uterine segment is well developed, the presenting
part is well down in the uterus, and there are no special fetal re-
quirements.
Once the uterus is opened, the breech is delivered by total breech
extraction (see below). If most expeditious, the fetus is grasped (as
with vaginal delivery) over the hips with the thumbs on the sacrum
and the fetus gently extracted at a moderate rate. In some cases,
delivery is facilitated by first delivering the legs. This may be
accomplished by either directly grasping the feet or by flexing the
knees to facilitate grasping and delivering the feet. At the level of
the shoulders, the arms are swept out of the uterus by pressure
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412 HANDBOOK OF OBSTETRICS AND GYNECOLOGY
along the anterior portion of the humerus. Care is taken not to

overextend the neck. Gentle pressure on the uterus (by the assistant)
immediately above the head, while the obstetrician supports the body,
facilitates delivery of the head. The cord is immediately clamped.
Vaginal Delivery of the Breech Presentation
Vaginal delivery is facilitated by: a generous episiotomy, allowing
the fetus to be expelled to the level of the umbilicus before manip-
ulation, loosening and drawing down a short loop of cord when the
umbilicus come through the introitus, and having the assistant sup-
port the body while the head is being delivered.
Delivery of the Body
There are three methods for breech delivery of the body. Total
breech extraction involves grasping both of the lower extremities
initially, and then the pelvis when it is available, to literally extract
the fetus from the uterus and birth canal. This is the most hazardous
method of vaginal delivery. Spontaneous expulsion is simply al-
lowing full delivery of the body without manipulative interference
and is intermediate in fetal hazard. The safest vaginal breech de-
livery is assisted breech delivery. In this case, the fetus is sponta-
neously expelled to the level of the umbilicus and the remainder of
the fetus is extracted by gentle pressure on the pelvis with the ob-
stetrician’s thumbs over the sacrum.
While an assistant supports the body, the obstetrician rotates the
fetus as it descends so that the spine is in the midline directly un-
der the symphysis pubis. Gentle downward pressure on the pelvis
brings both scapulas under the symphysis. Rotation of the body
brings the right shoulder beneath the pubic symphysis. The opera-
tor (using the right hand) locates the right humerus and exerts gen-
tle pressure on the anterior surface until the arm is delivered. The
left arm is likewise delivered (Fig. 14-3).
Delivery of the Head (Figs. 14-4 and 14-5)

As the body is rotated back to the mid position, delivery of the head
is commenced. During this time, fundal pressure by an assistant
keeps the head flexed and the body is gently lifted upward. Usu-
ally the head delivers spontaneously over the perineum. When as-
sistance for delivery of the head in breech births is necessary, it can
be accomplished manually or with forceps. The Mauriceau-Smellie-
Veit maneuver involves the obstetrician placing the index and mid-
dle finger of one hand over the maxilla as the body rests of the fore-
arm. Two fingers of the operator’s other hand are applied on either
side of the neck with gentle traction. As the body is elevated, this
allows controlled delivery of the mouth, nose, and brow.
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NONVERTEX PRESENTATIONS, SHOULDER DYSTOCIA
413
FIGURE 14-3. Assisted breech delivery of the fetal body.
BENSON & PERNOLL’S
414 HANDBOOK OF OBSTETRICS AND GYNECOLOGY
Piper forceps, the second method of assisted breech delivery,
are specifically designed for breech birth. Moreover, their routine
utilization has been reported to improve neonatal outcomes in
1000–3000 g fetuses. The prerequisites for using Piper forceps in-
FIGURE 14-4. Initial operator and assistant positioning for the Mauriceau-
Smellie-Veit maneuver.
FIGURE 14-5. Final operator and assistant positioning for the Mauriceau-
Smellie-Veit maneuver for breech delivery of the fetal head.
clude: operator expertise, a completely dilated cervix, and engage-
ment of the head in the pelvis. Preferably, the head is in the direct
occiput anterior position. As the assistant supports the body, the op-
erator gently inserts the Piper forceps on each side of the head.
Keeping the body close to the forceps allows gentle traction, ap-

plied as the forceps are rotated anterior to accomplish a controlled
delivery (Fig. 14-6).
Complications of Vaginal Breech Delivery
One of the most immediate and feared complications of vaginal de-
livery is cervical entrapment of the head. Without prompt delivery,
severe asphyxia leads to fetal injury or death. Entrapment of the
head is most likely to result when the incompletely dilated cervix
affords passage of the body, but not the head. Thus, this complica-
tion most frequently occurs in those fetuses the least well prepared
to tolerate any trauma, the premature breech presentation. Gentle
downward shoulder traction with combined fundal pressure (by the
assistant) may afford delivery. If this fails, deep anesthesia
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NONVERTEX PRESENTATIONS, SHOULDER DYSTOCIA
415
FIGURE 14-6. Piper forceps for breech delivery of the fetal head indicat-
ing assistant support of the fetal body.
BENSON & PERNOLL’S
416 HANDBOOK OF OBSTETRICS AND GYNECOLOGY
(halothane has been classically used) to afford cervical relaxation
may be useful. Failing with the first two options, Duhrssen’s
incisions (hystrostomatomy) may preserve fetal life. These are sim-
ply incisions made into the cervix. Most recommend starting at
6 o’clock and then making additional incisions if necessary at 2 and
10 o’clock. With delivery, the incisions may extend upward into the
lower uterine segment and result in hemorrhage. Fortunately,
Duhrssen’s incisions are rarely necessary.
There are also a number of other potential complications of vagi-
nal delivery of breeches. Umbilical cord prolapse is associated with
15% of footing, 5% of complete, and only 0.5% of frank breech

presentations. Direct birth trauma as the result of difficult delivery
has been said to be Ͼ10-fold more common in breech vaginal de-
liveries compared to vertex. The arms may slide behind the neck
(nuchal arms) and obstruct delivery and/or be injured by attempts
at displacement.
PROGNOSIS
Breech fetuses may be neurologically different from cephalic in oth-
erwise healthy pregnancies. There is a negative association between
breech presentation and cognitive outcomes regardless of delivery.
In the absence of birth injury, the higher risk of cerebral palsy among
term breech presentation may relate more to the small for gesta-
tional status of the breech than to mode of delivery. Short-term data
(see previous discussion) for cord blood acid–base studies, Apgar
scores, and neonatal intensive care admissions all indicate that vagi-
nal delivery has more short term effects than cesarean, but there
are studies indicating that vaginal delivery in carefully selected pa-
tients is an acceptable alternative.
Overall, breech presentation remains a high-risk pregnancy with
a lasting impact on the parents. Even parents undergoing cesarean
for breech presentation have been found to have lower subsequent
pregnancy rates (than vertex). This most probably relates to deci-
sions not to reproduce.
OTHER MALPRESENTATIONS
TRANSVERSE LIE
Transverse lie is a position where the fetal long axis lies at right
angles to the maternal long axis. Although more frequent in earlier
gestation, transverse lie occurs in ,0.5% of term singleton
pregnancies. With higher order gestations, there is a marked
increase in malpresentations. In singleton pregnancies the most
common associations are increasing multiparity (relaxation of the

abdominal wall and uterus), placenta previa, fetal abnormalities,
and contraction of the bony pelvis. Perinatal mortality is markedly
increased with transverse lie, exceeding 10%.
Diagnosis most often suggested by Leupold’s maneuvers and
finding the fetal heart (auscultation or Doppler) in an unexpected
area. Confirmation is achieved by sonography. Moreover, full sono-
graphic evaluation is warranted to exclude fetal anomalies. This
evaluation will also detail whether the fetal back is “down” (infe-
rior in the uterus) or “up” (superior in the uterus). The latter is even
more hazardous for cord prolapse should the membranes rupture.
Corrective maneuvers have not proven useful and the presentation
is not amenable to delivery. Thus, cesarean section is recommended
when the fetus is mature.
Lesser angulations of axis disalignment are termed “oblique
lies.” When vertex, these usually spontaneously convert, but war-
rant close follow-up.
SHOULDER DYSTOCIA
Shoulder dystocia is an obstetric emergency occurring in cephalic
presentations when the shoulders fail to deliver despite the per-
formance of routine obstetric maneuvers. Characteristically, the head
delivers and remains near transverse, the final phase of external
rotation (the head reassuming the position it originally emerged) does
not occur; the chin is tightly applied to the perineum and the face
become progressively cyanotic. The anterior shoulder is impacted
behind the symphysis pubis and the posterior shoulder is lodged
against the bony pelvis at an angle precluding further descent.
Although shoulder dystocia may occur with any term fetus, and
50%–90% of cases occur in normally grown fetuses, it increases
with increasing fetal size. Any antecedent of macrosomia (see p. 219)
places a gravida at increase risk of shoulder dystocia with deliv-

ery, including: maternal diabetes (odds ratio 1.7) or gestational di-
abetes, obesity, previous macrosomic fetus, maternal birth weight
Ͼ8 lb, maternal weight gain of Ͼ20 kg during pregnancy, and ab-
normal fetal growth factors or syndromes. Occurrence data detail
the relationship of shoulder dystocia to fetal size in pregnancies not
complicated by diabetes and the enhancement in those complicated
by diabetes: 0.15% of deliveries Ͼ2500 g, 3% of deliveries
Ͼ3500 g, 5.2% (12.2% with diabetes) of deliveries 4000–4250 g,
9.1% (16.7% with diabetes) of deliveries 4250–4500g, 14.3%
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NONVERTEX PRESENTATIONS, SHOULDER DYSTOCIA
417
BENSON & PERNOLL’S
418 HANDBOOK OF OBSTETRICS AND GYNECOLOGY
(27.3% with diabetes) of deliveries 4500–4750 g, and 21.1% (34.8%
with diabetes) of deliveries 4750–5000 g.
Shoulder dystocia is increased by more than a third in vacuum
or forceps assisted births (to between 4.6%–45%). If the fetus is
Ͼ4000 g, and there is a prolonged second stage and midpelvic
intrumentation, shoulder dystocia has been reported to be as high
as 23%. Conditions that create larger and/or more rigid shoulders
or fetal disproportion (most notably diabetes) increase the inci-
dence of shoulder dystocia. This may account for the increase in
shoulder dystocia with postdate pregnancies and in recurrent
shoulder dystocia. Additional correlates of shoulder dystocia
include induction of labor (odds ratio 1.3). However, the majority
(.50%) of shoulder dystocia occurs without identifiable risk factors.
Although there is an increased risk of maternal morbidity (e.g.,
extended epiosotomy, vaginal or cervical lacerations, other trauma
associated with delivery, and excessive blood loss) with shoulder

dystocia, the major risks are to the fetus. Indeed, up to 50% of
neonates with this complication have been reported to have birth
asphyxia or traumatic injury. Birth asphyxia may include noth-
ing more severe than metabolic acidosis, or may involve shock,
central nervous system depression, seizures, long-term central
nervous system damage, organ failure, and death. The traumatic
neonatal injuries include fractures of the clavicle or humerus and
brachial plexus trauma. In the absence of other complications, the
fractures generally heal without incident. Most brachial plexus
trauma resolves with minimal or no neurological deficit (particu-
larly with proper rehabilitation), but avulsion of nerves may lead
to Erb’s palsy.
Prevention, the ideal treatment, is thwarted by shoulder dysto-
cia’s unpredictability (50% of cases do not have predisposing signs).
Even the ability to detect macrosomia (see p. 219) by ultrasound or
clinical means is limited. Although many authorities recommend
cesarean section for fetuses with estimated birth weights Ͼ5000 g,
performing a cesarean for every fetus suspected to be macrosomia
has not proven medically or cost effective. Moreover, reports of la-
bor induction for antenatally predicted fetal macrosomia indicate a
marked increase in cesarean section without significant reduction
in shoulder dystocia or fetal injury.
There should be an enhanced level of vigilance for shoulder dys-
tocia when the pregnancy is complicated by diabetes mellitus, when
there are labor abnormalities (protraction disorders, arrest disor-
ders, or a prolonged second stage of labor), if mid-pelvic instru-
mentation is necessary, and in macrosomic fetuses. Preventative
measures at the time of delivery include suprapubic pressure ap-
plied by an assistant as the head delivers and maximally flexing the
maternal legs at the hips (McRoberts maneuver).

In unavoidable cases, management requires clinical judgment
and individualized care. Time is of the essence. The fetus is at risk
of asphyxiation, because it cannot expand the chest to breathe and
umbilical cord circulation is compressed within the birth canal. Clin-
icians are encouraged to have a careful, methodical series of ma-
neuvers designed to dislodge the shoulder from behind the pubic
symphysis so that delivery may occur. Operator experience and case
individualization mandates using the maneuvers in the order most
likely to be effective; therefore, the following should not be inter-
preted as being in any recommended order.
●
Summon the additional assistance necessary for the emer-
gency (e.g., anesthesiology, neonatal resuscitation, addi-
tional physicians, or nursing staff).
●
Create (or extend) an episiotomy allowing sufficient room
for vaginal maneuvers. This may require proctoepisiotomy.
●
Perform the McRoberts maneuver.
●
Exert suprapubic pressure (Rubin’s maneuver).
●
Perform the Wood’s maneuver, which is to place two fin-
gers against the anterior surface of the posterior shoul-
der and apply gentle, but firm, pressure while attempting
rotation.
●
Attempt to deliver the posterior arm.
In those uncommon cases (probably Ͻ2%) not corrected by
these maneuvers, a series of extraordinary maneuvers have been

suggested, but all carry significant risk. Fracture of the clavicle will
relieve the shoulder rigidity and is best accomplished by pressure
away from underlying structures if a finger can be hooked behind
the clavicle in the mid portion of the supraclavicular space. Frac-
ture toward the underlying structures as well as attempting to cut
the clavicle with scissors places both great vessels and nerves at
risk. The Zavinelli maneuver entails deep anesthesia for uterine re-
laxation and sufficient pressure on the fetal head to replace it within
the upper vagina or uterus, where cesarean can then be performed
to complete delivery. Because the need for this is rarely encoun-
tered, it is difficult to maintain operator proficiency and the infec-
tious complications are high. Symphysisotomy is utilized in many
developing countries and appears to have relatively low morbidity
and few sequelae. Again, it is difficult to maintain operator profi-
ciency in this country.
There is significant recurrence risk for gravidas who have had
prior shoulder dystocia (14ϫ, 1% increased to 14%) and traumatic
birth (3-fold increase). Should cesarean not be employed, patients
CHAPTER 14
NONVERTEX PRESENTATIONS, SHOULDER DYSTOCIA
419
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420 HANDBOOK OF OBSTETRICS AND GYNECOLOGY
in the latter two categories should be aware of their increased risk
with attempting vaginal birth.
UMBILICAL CORD PROLAPSE
Cord prolapse occurs when the presenting part does not fill the
lower uterine segment and impinge on the cervix (Fig. 14-7). This
allows the cord to enter this space and lie alongside (occult) or lower
(overt) than the presenting part. The overt form is far more serious

and is highly associated with malpresentation, as reflected by the
incidence with the following conditions: transverse lie (20%),
footling breech (15%), complete breech (5%), and frank breech
(0.5%).
OVERT CORD PROLAPSE
The incidence of overt cord prolapse with singleton gestations has
been variously reported from 0.1%–0.5%. About 50% of cases oc-
cur with breech presentations, and another 10% with transverse pre-
sentations, whereas 40% occur with vertex presentations. Nearly
two thirds of overt cord prolapse occurs in multiparas. Due to in-
creased instability and malpresentations, the incidence is higher
with twins (accounting for 25% of all cord prolapses) and still higher
with higher order multiple gestations. Overt cord prolapse occurs
more frequently with low birth weight infants, in contrast to occult
prolapse of the cord.
When the cord is presenting, it may be palpated through the mem-
branes if there is cervical dilatation. Complete prolapse of the um-
bilical cord is associated with rupture of the membranes. The patient
may feel the cord slide through the vagina and over the vulva after
the membranes rupture. When the cord is first compressed, there
may be violent fetal activity. The cord may be seen or palpated and
the fetal heart tones will reflect cord compromise.
More than 15% of these patients present with an intrauterine
fetal demise. These cases are managed conservatively by allowing
delivery to proceed. When the fetus is viable and there is complete
cord prolapse, the patient should be placed immediately in the knee-
chest or deep Trendelenburg position. A sterile gloved hand is used
to put pressure upward on the presenting part to relieve cord com-
pression. Attempts at cord reposition are nearly fruitless, but the
cord is palpated for viability and fetal heart tones are monitored

continuously. Oxygen is administered to the mother. Delivery is ac-
complished as quickly as possible. The mode of delivery depends
CHAPTER 14
NONVERTEX PRESENTATIONS, SHOULDER DYSTOCIA
421
FIGURE 14-7. Umbilical cord prolapse. Occult and forelying cords occur
with intact membranes, while complete cord prolapse occurs with membrane
rupture.
BENSON & PERNOLL’S
422 HANDBOOK OF OBSTETRICS AND GYNECOLOGY
on the cervical dilatation, but nearly all will be delivered by ce-
sarean section.
Perinatal mortality, even in modern centers, exceeds 35% and
morbidity of survivors is variously reported.
OCCULT CORD PROLAPSE
The vast majority of occult cord prolapse is only diagnosed by elec-
tronic fetal monitoring criteria and there is no consistent physical
finding. The fetal heart varies in relation to a contraction with a
characteristic pattern in occult cord prolapse. Early and late in the
contraction, when there is only enough pressure to impinge on the
venous circulation, the fetal heart will accelerate as a measure of
decreased venous return. With increasing pressure, there is arterial
impingement, initiating a baroreceptor response causing a marked
fall in fetal heart rate.
It is uncommon for cord impingement to be severe enough to
result in persistent severe variable decelerations. When this occurs,
however, it should be viewed as a sign of true fetal compromise for
there may be hypoxia, metabolic acidosis, and subsequent morbid-
ity or mortality. A pelvic examination is conducted to rule out overt
cord prolapse, and the patient’s position changed (often to the Sims

or Trendelenburg). Oxygen is administered and the monitoring is
closely observed. In the majority, the cord impingement is suc-
cessfully resolved and labor proceeds without incident. Only occa-
sionally will cord impingement as a result of occult cord prolapse
require cesarean section for fetal compromise.