Shoulder Dystocia & Erb’s Palsy
(Brachial Plexus Injury)
Author:
Craig V. Towers, M.D., F.A.C.O.G.
Objectives: Upon the completion of this article the reader will be able to:
1.
Define shoulder dystocia and brachial plexus injury and discuss the relationship between
these two entities.
2.
Discuss the warning signs and risk factors surrounding shoulder dystocia and whether a
shoulder dystocia event is predictable.
3.
Explain the various maneuvers that may be performed in order to relieve a shoulder
dystocia.
4.
Describe the issues of informed consent regarding shoulder dystocia and how brachial
plexus injury can occur in non-shoulder dystocia deliveries.
Definition
Shoulder dystocia is defined as a delivery in which the fetal shoulders do not delivery
following gentle downward traction on the baby’s head that requires the use of additional obstetrical
maneuvers in order to complete the delivery. This article will discuss all of the issues listed below
that are related to this obstetrical emergency.
1
Incidence and general overview
2
Risk factors / potential warning signs / & predictability
3
Obstetrical maneuvers that can be utilized
4
Informed consent and scheduled cesarean section
5
Other facts
Incidence and General Overview
Understanding the statistics of shoulder dystocia and Erb’s palsy is probably one of the most
important areas of this article. The overall incidence of shoulder dystocia is approximately 1% of all
deliveries. In studies, the rate varies between about 0.5% to 1.5% depending on the definition for
shoulder dystocia that was used and the population studied. What is true is that this rate increases
as birthweight increases. On average, the risk of shoulder dystocia is probably about 0.5 % for
births under 4000 grams, 2% to 3% for births between 4000 and 4500 grams, and 4% to 15% for
births greater than 4500 grams.
Even thought the risk for shoulder dystocia is greater in births over 4000 grams, the overall
number of shoulder dystocia deliveries is about 50/50 for births under 4000 grams and births over
4000 grams. This is because 85% to 90% of all births result in babies that are less than 4000 grams.
This is an important fact when we discuss the predictability of shoulder dystocia later on in this
article.
The incidence of brachial plexus injury is somewhat different. It is important to understand
that most shoulder dystocia deliveries do not result in Erb’s palsy. Likewise, approximately half of
the Erb’s palsies that are seen come from deliveries in which there was no shoulder dystocia. This
is a fact that needs to be understood. For years, nearly every textbook in obstetrics and pediatrics
stated that if a baby was found to have an Erb’s palsy following birth, then a shoulder dystocia must
have occurred and the delivering healthcare provider probably applied excessive downward traction
in the delivery of the anterior shoulder. It was not until the mid to late 1990’s that research began
to look at this question and has now shown that in fact this belief was terribly incorrect.
Using one of the largest studies ever published on brachial plexus injury, the incidence of
Erb’s palsy is approximately 0.15% of all deliveries (which is about 1 in every 650 to 700 births). It
is now a truth that only about half of these brachial plexus injuries come from a delivery
complicated by shoulder dystocia. The other half comes from deliveries in which NO shoulder
dystocia occurred. This fact has now been demonstrated in numerous studies that total more than
2600 Erb’s palsies (seen in the table below). Shoulder dystocia, however, is definitely a risk factor
when it comes to brachial plexus injuries and this statistic will be further clarified under the heading
of “Risk Factors” seen below.
Author
Erb’s with SD
Erb’s without SD
Total
Levine 1984
8
28
36
Gonik 1991
14
13
27
Jennett 1992
17
22
39
Nocon 1993
28
5
33
Lipscomb 1995
7
5
12
Perlow 1996
12
4
16
Sandmire 1996
19
17
36
Graham 1997
8
7
15
Peleg 1997
15
36
51
Brown 1997
17
13
30
Ecker 1997
43
37
80
Gherman 1998
23
17
40
Shivvers 1998
78
108
186
Gilbert 1999
860
751
1611
Raio 2003
58
36
94
Evans-Jones 2003
206
117
323
Totals
1413 (53.7%)
1216 (46.3%)
2629
In conjunction with the large numbers seen in the table above, there are two other
compelling facts that verify the issue that most brachial plexus injuries are not caused by the
delivering healthcare provider. These are cesarean section and the posterior arm. Before these
facts can be discussed, the origin of a brachial plexus injury / Erb’s palsy must be understood.
These injuries are caused by a stretching of the nerves in the neck region in the area of C-5 to T-1
(cervical nerve roots 5, 6, 7, & 8 and thoracic nerve root 1). These nerves will be further discussed
under “other facts” seen below. However, to say it again, these injuries are caused by stretching of
the nerves beyond their capacity. Pulling on the baby’s head straight out does not cause the injury
(this would result in further shoulder impaction and possible spinal cord injury for the baby). Erb’s
palsy is a traction or vector injury. The fact that numerous case reports exist of brachial plexus
injuries identified following cesarean section verifies that this stretching can occur in utero. In fact,
60 of the 1611 Erb’s palsies (4%) seen in the Gilbert study occurred in a cesarean section delivery.
Therefore, not all brachial plexus injuries occur in vaginal deliveries.
Furthermore, everyone would agree that human anatomy varies from person to person. If
we examine the population of the world, we will see some individuals with very long necks and
some with very short necks and everything in between. Likewise, the birth canals of women also
vary. The distance from behind the pubic bone to the perineum (or just outside the birth canal) is
not the exact same distance for all pregnant women. Thus, if a baby with a relatively short neck
delivers vaginally in a woman with a long distance from behind the pubic bone to the perineum, the
nerves in the neck region can be stretched beyond their capacity upon delivery of the head before
any healthcare provider applies any downward traction. In this same mother-baby delivery
scenario, the nerves in the neck may be stretched up to their capacity upon delivery of the head but
are stretched beyond their capacity when the normal amount of gentle downward traction is applied.
Finally, in the face of a shoulder dystocia, the nerves in the baby’s neck can be damaged if excessive
downward traction is applied. This is why excessive downward traction (for the most part) should
be avoided and other maneuvers utilized when a shoulder dystocia is encountered (these maneuvers
will be discussed below).
The posterior arm is the second compelling finding that verifies that the delivering
healthcare provider does not cause most brachial plexus injuries. Again, in the past it was presumed
that all brachial plexus injuries occurred because of excessive traction on the anterior shoulder in a
delivery complicated by a shoulder dystocia. Along with the fact that numerous studies now show
that approximately half of the injuries are seen in deliveries with no shoulder dystocia, several recent
studies have now identified that approximately one-third of all Erb’s palsies are seen in the posterior
arm of the baby. The theory behind this occurrence is that during the labor process of some
pregnancies, the baby’s posterior shoulder becomes entrapped on the sacral promontory. When the
head delivers, the stretch from this point to just outside the birth canal is tremendous and is much
further than the distance from behind the pubic bone to just outside the birth canal. In addition,
when a baby’s head delivers in this situation, the gentle downward traction that is applied will
actually shorten the distance between this entrapped posterior shoulder and would be beneficial
rather than harmful. The importance of this finding is that none of the maneuvers applied by the
delivering healthcare provider will actually further stretch the nerves in a posterior arm injury. If
anything, they will actually shorten the distance. Thus, a brachial plexus injury of a posterior arm
occurs with the delivery of the head prior to any maneuvers utilized by the healthcare provider. It
should be mentioned that upward traction on a baby’s head prior to the delivery of the anterior
shoulder is not a recognized obstetrical maneuver, will not result in the delivery of the posterior
shoulder before the anterior shoulder, and should not be used.
Therefore to summarize the four possibilities, the stretching of the nerves in a baby’s neck
can occur in utero prior to the onset of labor; can occur following the delivery of the head before
any downward traction is applied; can occur with the normal amount of downward traction applied
in normal deliveries; and can occur with excessive traction in the face of a shoulder dystocia.
Risk Factors / Potential Warning Signs / & Predictability
Numerous studies have been published over the years that have looked at shoulder dystocia
and potential risk factors. However, from a simplistic point of view, there are 2 basic risk factors
for shoulder dystocia and these are a baby that is too large for the mother’s birth canal (macrosomia,
most commonly defined as > 4500 grams) or a mother’s pelvis that is too small or poorly shaped for
the birth of the baby (non-macrosomic baby) or a combination of the two. A third potential risk
factor is diabetes, which will be discussed in more detail below. Numerous other “described” risk
factors have been studied, but none of them alone or in combination can accurately predict when a
shoulder dystocia will occur. In the majority of studies, the ability to predict a shoulder dystocia
was well below 50%. Only a few have had a prediction rate of greater than 50%, none were above
75%, and none have been re-producible. Therefore, shoulder dystocia cannot be accurately
predicted nor prevented (a statement concurred by ACOG). This means that every healthcare
provider who performs vaginal deliveries will experience a shoulder dystocia and will need to know
how to handle the situation when it arises.
Nevertheless, even though shoulder dystocia cannot be accurately predicted, warning signs
and other “described” risk factors need to be reviewed. It should be noted that many of the
“described” risk factors that have been associated with shoulder dystocia are really risk factors for
macrosomia and if macrosomia is not present, then these are of no significance. Warning signs of
an impending shoulder dystocia primarily occur in a patient that is in labor. The only exception is a
prior history of a shoulder dystocia, especially one that occurred in a baby that was non-macrosomic.
This might imply that the primary factor lies with the size and/or shape of the mother’s pelvis. As
a review, there are 4 primary shapes to a mother’s pelvis. The most common shape is gynecoid,
which is seen in approximately 45% to 50% of women and is considered to be the most round in
shape. The second most common is the anthropoid pelvis, which is seen in about 30% of women
and is oval in an anteroposterior direction and could predispose to a persistent occiput posterior
(OP) position of the baby’s head in labor. The third most common pelvis is the android pelvis,
which occurs in about 20% of women and is heart shaped. Finally, the platypelloid pelvis is the
least common seen in only 3% of women and is oval from side to side (thus, the distance between
the pubic arch and sacrum is short). The platypelloid pelvis is the one that could predispose to a
shoulder dystocia, especially in the presence of a non-macrosomic baby.
There are 2 basic warning signs that occur in labor. These are a prolonged second stage of
labor and the need for instrumentation (use of a vacuum or forceps). Unfortunately, neither of
these alone or in combination can predict the occurrence of a shoulder dystocia. Therefore, if
either of these or both exist, the best approach is to be prepared for a shoulder dystocia in case one
occurs (preparation for a shoulder dystocia is discussed below). As a start, a few studies have
suggested that induction of labor, the use of epidural anesthesia, and the length of the first stage of
labor might be risk factors for a shoulder dystocia; however, the overwhelming data have shown that
they are not. Furthermore, the size and position of the fetal shoulders is unlikely to affect whether
or not the cervix will dilate to complete (which involves the first stage of labor). The size and shape
of the fetal shoulders may, however, affect how well the baby traverses the birth canal once the
mother has dilated to complete (which is the second stage of labor). Therefore, a prolonged second
stage of labor could be a warning sign for an impending shoulder dystocia.
In addition, a prolonged second stage of labor often goes hand-in-hand with the potential
need for the use of forceps or a vacuum to accomplish the delivery. It is extremely important to
remember that there needs to be an indication for the use of forceps and/or vacuum. The
indications for the use of forceps or vacuum (and the definition of a prolonged second stage of
labor) are as follows:
(1) maternal indications such as cardiac disorders, severe pulmonary disorders, hemorrhage,
etc. (or)
(2) fetal indications such as non-reassuring fetal heart tracings, etc. (or)
(3) prolonged second stage – ACOG has defined the length of the second stage and if these
times are exceeded, then a diagnosis of a prolonged second stage can be entertained. For
nulliparous women – 2 hours without regional anesthesia, 3 hours with regional anesthesia;
For multiparous women – 1 hour without regional anesthesia, 2 hours with regional
anesthesia.
Maternal exhaustion is often listed as an indication for an instrumented delivery, but this diagnosis
cannot be made in a short period of time once the patient becomes completely dilated. Some
attempt needs to be made in coaching and educating the patient regarding how to create effective
pushing, including a discussion on the potential need for cesarean section, if she does not at least
attempt some pushing effort. In addition, there are basic requirements that need to be met when
using forceps or a vacuum and these requirements ARE THE SAME for both instruments. They
are a fully dilated cervix with an engaged fetal head at > +2 cm station (which corresponds to a
minimum of a low pelvic delivery). Midpelvic and/or high pelvic deliveries, for the most part,
should not be done.
Many other “described” risk factors have been evaluated over the years, including
obesity, excessive maternal weight gain (defined as > 20 kilograms or 44 pounds), postterm (> 42
weeks gestation), large fundal height measurements, and a prior delivery of a baby > 4000 grams.
These, however, are primarily risk factors for macrosomia. Again, if macrosomia is not present,
then these do not increase the risk for a shoulder dystocia.
Finally, regarding “risk factor” issues for shoulder dystocia, diabetes, especially insulin
dependent diabetes, produces two dilemmas. To begin with, diabetes can increase the risk for
macrosomia and macrosomia can increase the risk for shoulder dystocia. In addition, diabetes,
especially when poorly controlled, probably increases the risk for shoulder dystocia in babies that are
not macrosomic because of its potential effect on the final dimensions of the baby that delivers.
The reason for this is easier to explain with an example. Let’s say a given pregnancy was destined to
have a baby of 3200 grams and 21 inches in length. If this pregnancy were complicated by poorly
controlled diabetes, the baby may end up at 3700 grams but is still 21 inches in length, making the
dimensions of the baby “fatter” for its length increasing the chance for a shoulder dystocia.
Turning our attention to brachial plexus injury, shoulder dystocia is definitely a risk factor.
To show this, we need to review some statistics. To begin with, there are approximately 4 million
births in the United States every year. It has now been demonstrated in over 15 studies that about
50% of the Erb’s palsy cases occur in a shoulder dystocia delivery and the other 50% occur in
deliveries without a shoulder dystocia. If the incidence of Erb’s palsy is approximately 1 in 650 to
700 births, then about 6000 cases of brachial plexus injury will occur in a given year. If the overall
incidence of shoulder dystocia is 1%, then there are about 40,000 cases of shoulder dystocia per
year. Since approximately half of the Erb’s palsies that occur are seen in deliveries with a shoulder
dystocia, then 3000 brachial plexus injuries occur in these 40,000 deliveries or about 1 in 13
deliveries (7.5%). The other 3000 cases occur in the 3,960,000 births in which a shoulder dystocia
did not occur or about 1 in 1320 deliveries (.075%). Thus, a brachial plexus injury is about 100
times more likely to be seen in a shoulder dystocia delivery, which is why most healthcare clinicians
had the belief that the disorder could only occur in the presence of a shoulder dystocia.
However, when we only examine shoulder dystocia deliveries, fortunately, the majority do
not result in a brachial plexus injury. In fact, the risk of having any level of Erb’s palsy develop in a
shoulder dystocia delivery is approximately 20% (plus or minus 5%). Of these, approximately 15%
are permanent (plus or minus 5%). Thus, in a 100 shoulder dystocia deliveries there will be
approximately 15-25 brachial plexus injuries and of these only 2-5 will be permanent (a 2% to 5%
overall permanent rate).
Obstetrical Maneuvers That Can Be Utilized
Numerous maneuvers (that might be utilized once a shoulder dystocia is recognized) have
been reported and evaluated over the years. Categorically, there are 5 basic groups, which are the
McRoberts maneuver, suprapubic pressure, rotational maneuvers, delivery of the posterior arm, and
heroic procedures. One of the easiest and most often utilized maneuvers is McRoberts, which was
described in 1983 and involves hyper-flexing the legs back toward the mother’s abdomen. An
assistant may also apply suprapubic pressure as the operator performs normal downward traction on
the baby’s head. Suprapubic pressure involves the application of downward pressure just cephalic
to the mother’s pubic bone (in the area of the mother’s bladder).
The term “rotational maneuvers” is used in this manuscript because the words are often
intermixed and loosely applied by healthcare providers (i.e. Woods maneuver, corkscrew maneuver,
Woods screw maneuver, Rubin maneuver, etc.). As a purist, in 1943, Woods described a maneuver
of placing a hand on the chest side of the posterior shoulder of the baby and trying to rotate the
posterior shoulder upward 180 degrees. This would cause the anterior shoulder to fall below the
pubic bone and conceptually, the baby would move in a corkscrew pattern. In 1964, Rubin
described placing a hand (on the back side of the baby) behind either the anterior or posterior
shoulder (which ever was the easiest to access), and applying pressure to fold the shoulders toward
the chest. In essence, rotational maneuvers involve placing a hand on the baby’s shoulders and
applying pressure that rotates the position of the baby in the birth canal.
Delivery of the posterior arm involves the operator placing a hand into the vaginal canal
posteriorly up to a distance where the posterior arm of the baby is identified. The arm is then
grasped and swept across the baby’s chest and out the birth canal, which will result in the anterior
shoulder dropping below the pubic bone allowing for delivery. This procedure, though very
successful, can often result in a fracture of the baby’s humerus.
Heroic maneuvers have also been described but should only be utilized if the above 4
categories are not successful. In addition, some of these maneuvers require extra training. These
include the deliberate fracture of the baby’s clavicle (which is extremely difficult to do), cleidotomy
(which is transecting the baby’s clavicle with the use of scissors), symphysiotomy (which is
transecting the fibrous tissue between the pubic bones of the mother’s pelvis), and the Zavanelli
maneuver, also called cephalic replacement (reported in 1985 and involves placing the baby’s head
back into the birth canal and performing a cesarean section). The published reports on the
Zavanelli maneuver have shown mixed results ranging from normal outcomes to severe injuries and
stillbirth.
Regarding the maneuvers, three other areas need to be discussed. The first is the use of
fundal pressure. This maneuver can be used PRIOR to the delivery of the baby’s head and as a
purist; fundal pressure is utilized in nearly every term cesarean section to effectuate the delivery.
However, fundal pressure should not be used once the head has delivered because it will not help in
delivering the shoulders, can further impact the anterior shoulder against the mother’s pubic bone,
and if applied while the operator uses downward traction on the baby’s head could lead to injury.
The second area is the use of an episiotomy. An episiotomy will not result in the delivery of the
baby in the case of a shoulder dystocia because the baby is not impacted on soft tissue. However,
an episiotomy can allow more room for the operator’s hand to perform rotational maneuvers or
delivery of the posterior arm.
The third issue is the use of traction. Downward traction IS USED in the overwhelming
majority of deliveries. In fact, the definition of a shoulder dystocia is when the baby’s shoulders do
not deliver following the use of normal downward traction. Once the diagnosis is made, the
maneuvers above should be utilized. Excessive downward traction, however, can result in injury to
the baby’s brachial plexus and should be avoided unless all other maneuvers fail and the decision is
made to potentially sacrifice the arm in order to prevent neonatal brain injury or death. Though
very few studies exist on this topic, it appears that neonatal brain injury can begin to occur if the
shoulder dystocia extends beyond 5 minutes (though this area is not black and white and also
involves the status of the baby prior to the delivery of the head). Again, upward traction on the
baby’s head should not be performed prior to the delivery of the anterior shoulder because it is not a
recognized obstetrical maneuver and will not result in the delivery of the posterior shoulder before
the anterior shoulder.
Informed Consent and Scheduled Cesarean Section
One could argue that informed consent and shoulder dystocia are words that should not
occur in the same sentence. The reason is because shoulder dystocia is unpredictable. However,
informed consent can still play a role in this arena. Good labor management still involves an
attempt at estimating fetal weight. Though our ability to accurately estimate fetal weight is often
abysmal, we as healthcare providers should still make an assessment and if we believe the fetal
weight might be macrocosmic, options should be given to the patient. These include the options of
a cesarean section and its associated risks versus the risks of a vaginal delivery in the face of potential
macrosomia. Also included in this discussion is that our estimate may be off and an unnecessary
procedure might occur. This estimated fetal weight can occur by either ultrasound or physical
examination (Leopold maneuvers). Studies have not really shown one to be superior to the other.
In fact, one study showed that the mother’s prediction was closer than either an ultrasound or
physical evaluation.
If the healthcare provider believes that macrosomia might be present, and the patient
chooses to proceed with a vaginal delivery, it would be prudent to have extra help present at the
time of delivery. In addition, though no studies exist on this issue, the use of forceps or a vacuum
in this setting may also not be warranted. If the patient is unable to push the baby out, the safest
approach might be to proceed with a cesarean section (especially if the labor has a prolonged second
stage).
Regarding the issue of a scheduled cesarean section for the purpose of preventing a shoulder
dystocia, ACOG has recommended that it be considered if the estimated fetal weight exceeds 5,000
grams in non-diabetics or 4,500 grams in women with diabetes. Again, these recommendations
were made because of the high error rate in accurately predicting macrosomia combined with the
overall risks of permanent injury with vaginal delivery in cases of macrosomia versus the risks of
cesarean section.
Other Facts
One concept that may be difficult for some healthcare providers to comprehend is how
brachial plexus injuries can occur without a shoulder dystocia or the use of excessive traction. To
begin with, numerous injuries and findings are seen in normal spontaneous (non-instrumented)
vaginal deliveries, both to the mother and the neonate. Some of the reported injuries for the
mother include significant cervical and perineal tears, pelvic nerve injuries, a fractured coccyx, and a
separated symphysis pubis. For the neonate, there is significant molding of the head, fractured
skulls, subdural hematomas, fractured clavicles, and brachial plexus injuries. All of these and more
can occur because the power of the uterine muscle is formidable. It should be noted that nearly all
healthcare providers who perform deliveries are not strong enough to replace an inverted uterus
without the aid of some uterine muscle relaxation medication. This is because the force of the
uterus (endogenous), especially when combined with the force of the mother’s valsalva pushing
efforts, will often exceed 100 pounds. This endogenous force is 4 to 9 times greater than the
exogenous force utilized in deliveries by the healthcare provider. The explanation of this point is
very technical and involves the use of physics and is presented in the next paragraph for those who
are interested.
We measure the strength of uterine contractions by millimeters of mercury (mmHg). A
mmHg is a pressure measurement that is roughly equal to 30 pounds of force per square meter of
area. Using intrauterine pressure catheter data, the force of a uterine contraction combined with
the mother’s expulsive forces often equals 80 mmHg, which equates to about 2,400 pounds of force
per square meter of area. The cross-sectional area of the birth canal when the cervix is completely
dilated is about 80 square centimeters. If the force of a labor contraction and pushing were equally
distributed throughout the uterus (meaning that the force upward against the uterine wall in the
fundus were equal to the force downward through the birth canal), then the force in the birth canal
when a mother is completely dilated and is pushing would only be about 19 pounds. However, we
know that a labor contraction actually begins in the muscle fibers of the fundus and propagates
down the uterus toward the birth canal because its purpose is to push out what is contained inside
(i.e. the baby). Likewise, the direction of the valsalva-pushing maneuver is also downward toward
the birth canal. If the force of a labor contraction with pushing were equally distributed in all
directions within the uterus, the baby would not move. Thus, the amount of force that is directed
downward through the birth canal is 6 to 8 times greater than the force that would be pushing
upward on the wall of the uterus in the fundus. This equates to more than 100 pounds of force,
which explains why injuries can occur.
Finally, throughout this article we have used the words brachial plexus injury and Erb’s
palsy. The brachial plexus is a network of nerves that was briefly discussed at the beginning and
includes the nerves that are located in the neck from C-5 to T-1. For clarification purposes, an
Erb’s palsy is defined as an injury to the nerve fibers of C-5 and C-6, and mainly involves the
mobility of the shoulder. A Klumpke’s palsy is defined as injury to nerve fibers C-8 and T-1 and
involves the mobility of the hand. The C-7 nerve fibers primarily innervate the triceps muscle.
Though these explanations have been simplified and generalized, one should know that the C-5
through T-1 nerve fibers intermix with each other and the extent of immobility will vary from injury
to injury. For completion purposes, the C-4 nerve fibers innervate the diaphragm and if this is
damaged, the baby will often have significant problems with respiration. Also, there are
sympathetic nerve fibers that come off the lower cervical / upper thoracic nerve roots and these
fibers return back up to innervate portions of the face and eyelid. If these nerves are injured,
Horner’s syndrome with a drooping eyelid might be seen.
Conclusion
In conclusion, shoulder dystocia cannot be accurately predicted nor prevented. Therefore,
delivering healthcare providers need to be prepared in handling these obstetrical emergencies when
they occur. Likewise, nothing can be done to prevent the brachial plexus nerve injuries that occur
in cesarean section births or deliveries with no shoulder dystocia. Therefore, protocols that involve
shoulder dystocia deliveries will only have the potential of impacting half of the brachial plexus cases
that occur. Because these injuries can occur in deliveries without a shoulder dystocia, if a baby
sustains a brachial plexus injury in a delivery complicated by shoulder dystocia, this does not mean
that excessive traction was utilized. With that said, being prepared for shoulder dystocia is good
medicine.
Preparation:
1.
Perform an estimated fetal weight, document this, and discuss options with the patient if
there is a belief that macrosomia (> 4500 grams) might exist.
2.
Observe the length of the second stage of labor and do not hesitate to ask for more help at
the time of delivery, especially if the decision is made to use forceps or a vacuum.
3.
If forceps or vacuum are utilized, have a recognizable indication and be sure that all of the
requirements are met (completely dilated, engaged head at > +2 cm station).
4.
If a vaginal delivery attempt is made on a patient with diabetes (especially one with insulin
dependence that is poorly controlled), again do not hesitate to ask for more help at the time
of delivery (regardless of the estimated fetal weight).
5.
When a shoulder dystocia is encountered – call for help – both obstetrical and pediatric.
6.
Remember the maneuvers:
McRoberts – hyper-flexing the legs back toward the mother’s abdomen; Apply
suprapubic pressure;
Rotational maneuvers – Rubin’s or Wood’s
Delivery of the posterior arm
7.
Avoid fundal pressure once the baby’s head delivers. An episiotomy may give more room
for rotational maneuvers and / or delivery of the posterior arm.
8.
Write a note of the maneuvers utilized and the position of the baby’s head at the time it
delivered – remember these notes are for future healthcare providers to understand what
occurred at the delivery.
References or Suggested Reading:
1.
Shoulder dystocia. ACOG Practice Bulletin; Number 40, November 2002.
2.
Fetal macrosomia. ACOG Practice Bulletin; Number 22, November 2000.
3.
Operative vaginal delivery. ACOG Practice Bulletin; Number 17, June 2000.
4.
Evans-Jones G, Kay SPJ, Weindling AM, et al. Congenital brachial palsy: incidence, causes,
and outcome in the United Kingdom and Republic of Ireland. Arch Dis Child Neonatal Ed
2003;88:F185-F189.
5.
Raio L, Ghezzi F, DiNaro E, et al. Perinatal outcome of fetuses with a birth weight greater
than 4500 g: an analysis of 3356 cases. Europ J Obstet Gynecol Reprod Bio
2003;109:160-65.
6.
Gilbert AM, Nesbitt TS, Danielsen B. Associated risk factors in 1611 cases of brachial
plexus injury. Obstet Gynecol 1999;93:536-540.
7.
Shivvers S, McIntire D, Leveno K, et al. Risk of brachial plexus injury in shoulder dystocia
deliveries by birthweight. Am J Obstet Gynecol 1998;178:S77.
8.
Gherman RB, Ouzounian JG, Miller D, et al.. Spontaneous vaginal delivery: A risk factor
for Erb’s plalsy? Am J Obstet Gynecol 1998;178:423-7.
9.
Ecker JL, Greenberg JA, Norwitz ER, et al. Birth weight as a predictor of brachial plexus
injury. Obstet Gynecol 1997;89:643-7.
10.
Brown B, Karmin I, Lapinski R, et al. Dual mechanism responsible for brachial plexus
injuries. Am J Obstet Gynecol 1997;176:S137.
11.
Peleg D, Hasnin J, Shalev E. Fractured clavicle and Erb’s palsy unrelated to birth trauma.
Am J Obstet Gynecol. 1997;177:1038-40.
12.
Graham EM, Forouzan I, Morgan MA. A retrospective analysis of Erb’s palsy cases and
their relation to birth weight and trauma at delivery. J Matern Fetal Med 1997;6:1-5.
13.
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injury. Am J Perinatol 1991;8:31-4.
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About the Author:
Dr. Towers is currently on a sabbatical writing a series of books that deal with the safety of
over-the-counter drugs, herbal medications, and natural remedies used during pregnancy. The first
book is in print entitled “I’m Pregnant & I Have a Cold – Are Over-the-Counter Drugs Safe to
Use?” published by RBC Press, Inc.
Before his sabbatical, Dr. Towers was an Associate Professor in the Department of
Obstetrics and Gynecology at the University of California, Irvine. He also was the Director of
Perinatal Medicine at Long Beach Memorial Women’s Hospital in Long Beach California. He has
practiced clinically in the states of Kansas, California, and Wisconsin. Dr. Towers has multiple
publications in peer review medical journals and he has given lectures on a wide variety of obstetrical
and medical topics nationwide.
Examination:
1.
The overall incidence of shoulder dystocia is approximately ______ of all deliveries.
A.
0.01%
B.
0.1%
C.
1%
D.
3%
E.
5%
2.
Approximately ______ of the Erb’s palsies that are seen come from deliveries in which there
was no shoulder dystocia.
A.
5%
B.
15%
C.
25%
D.
50%
E.
65%
3.
The incidence of Erb’s palsy is approximately about 1 in every ________ births.
A.
6500 to 7000
B.
1000 to 1500
C.
650 to 700
D.
400 to 500
E.
150 to 200
4.
There are two other compelling facts that verify the issue that most brachial plexus injuries
are not caused by the delivering healthcare provider which are
A.
fundal pressure and a generous episiotomy
B.
C.
D.
E.
cesarean section and the posterior arm
the posterior arm and a generous episiotomy
Rubin maneuver and fundal pressure
diabetes and cesarean section
5.
Several recent studies have now identified that approximately _______ of all Erb’s palsies
are seen in the posterior arm of the baby.
A.
1/10
B.
1/7
C.
1/5
D.
1/4
E.
1/3
6.
The stretching of the nerves in a baby’s neck can occur in all of the following ways
EXCEPT
A.
with excessive pitocin usage in the first stage of labor
B.
in utero prior to the onset of labor
C.
following the delivery of the head before any downward traction is applied
D.
following the normal amount of downward traction applied in normal deliveries
E.
with excessive traction in the face of a shoulder dystocia
7.
The ability to accurately predict when a shoulder dystocia will occur is
A.
less than 0.5%
B.
less than 50%
C.
greater than 50%
D.
greater than 75%
E.
nearly 100%
8.
The maternal pelvic shape that is most likely to predispose to a shoulder delivery, especially
in the presence of a non-macrosomic baby is
A.
platypelloid
B.
android
C.
arthropoid
D.
gynecoid
E.
anthropoid
9.
There are 2 basic warning signs that occur in labor that may suggest a shoulder dystocia
could occur and these are
A.
diabetes and an estimated fetal weight of > 4000 grams
B.
epidural anesthesia and a prolonged first stage of labor
C.
an estimated fetal weight of > 4500 grams and the use of pitocin
D.
excessive maternal weight gain and a large fundal height
E.
a prolonged second stage of labor and the need for instrumentation
10.
Which of the following statements accurately defines a prolonged second stage of labor
according to ACOG?
A.
nulliparous woman at > 3 hours without regional anesthesia
B.
nulliparous woman at > 2 hours with regional anesthesia
C.
D.
E.
multiparous woman at > 2 hour without regional anesthesia
multiparous woman at > 2 hours with regional anesthesia.
multiparous woman at > 3 hours with regional anesthesia
11.
All of the following definitions are true EXCEPT
A.
excessive maternal weight gain is defined as > 20 kilograms or 44 pounds
B.
a postterm pregnancy is defined as > 42 weeks gestation
C.
the basic requirements that need to be met when using a vacuum are different than
the requirements that need to be met when using forceps
D.
a low pelvic delivery is defined as an engaged fetal head at > +2 cm station
E.
macrosomia is most commonly defined as > 4500 grams
12.
A brachial plexus injury is about _______ times more likely to be seen in a shoulder dystocia
vaginal delivery when compared to a non-shoulder dystocia vaginal delivery.
A.
5
B.
25
C.
50
D.
75
E.
100
13.
The maneuver that involves hyper-flexing the legs back toward the mother’s abdomen is
called the
A.
Rubin’s
B.
Woods
C.
McRoberts
D.
Zavanelli
E.
cleidotomy
14.
The maneuver that is most likely to result in a fracture of the baby’s humerus (if this fracture
were to occur) is
A.
delivery of the posterior arm
B.
McRoberts
C.
Rubin’s
D.
Woods
E.
Zavanelli
15.
Which of the following maneuvers is an heroic maneuver that should only be utilized if all
the other recognized maneuvers are not successful
A.
Woods
B.
a generous episiotomy
C.
Rubin’s
D.
delivery of the posterior arm
E.
Zavanelli
16.
Regarding an episiotomy, which of the following statements is true?
A.
It should be performed prior to the use of fundal pressure.
B.
This maneuver can result in the delivery of the baby in the case of a shoulder.
C.
It should be performed in order to facilitate the Zavanelli maneuver.
D.
E.
It can allow more room for the operator’s hand to perform rotational maneuvers or
delivery of the posterior arm.
It will help minimize the amount of upward traction that is applied in order to
deliver the posterior shoulder prior to the anterior shoulder.
17.
Though very few studies exist on this topic, it appears that neonatal brain injury can begin to
occur if the shoulder dystocia extends beyond ____ minutes.
A.
2
B.
5
C.
9
D.
12
E.
15
18.
Regarding the issue of a scheduled cesarean section for the purpose of preventing a shoulder
dystocia, ACOG has recommended that it be considered if the estimated fetal weight
exceeds _______ grams in a non-diabetic.
A.
3500
B.
4000
C.
4500
D.
5000
E.
5500
19.
The endogenous force of the uterus, especially when combined with the force of the
mother’s valsalva pushing efforts is ________ than the exogenous force utilized in deliveries
by the healthcare provider.
A.
2 to 4 times greater
B.
4 to 9 times greater
C.
10 to 15 times greater
D.
5 to 10 times less
E.
3 to 5 times less
20.
In general terms, an Erb’s palsy is defined as an injury to the nerve fibers of ______, and
mainly involves the mobility of the shoulder.
A
C-5 and C-6
B.
C-7 only
C.
C-7 and C-8
D.
C-8 and T-1
E.
C-4 only