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Shoulder Dystocia

WHEC Practice Bulletin and Clinical Management Guidelines for healthcare providers. Educational grant provided by Women's Health and Education Center (WHEC).

Shoulder dystocia is most often defined as a delivery that requires additional obstetric maneuvers following failure of gentle downward traction on the fetal head to effect delivery of the shoulders. It is most often an unpredictable and unpreventable obstetric emergency. Failure of the shoulders to deliver spontaneously places both the pregnant woman and fetus at risk for injury. Shoulder dystocia is caused by the impaction of the anterior fetal shoulder behind the maternal pubis symphysis. It also can occur from impaction of the posterior fetal shoulder on the sacral promontory. The reported incidence ranges from 0.6% to 1.4% among vaginal deliveries of fetuses in the vertex presentation. Several maneuvers to release impacted shoulders have been developed, and they are described below.

The purpose of this chapter is to provide clinicians with information regarding management of deliveries at risk for or complicated by shoulder dystocia.

Maternal Complications:

The rate of postpartum hemorrhage is reported to be about 11% and the rate of fourth-degree lacerations about 3.8%. These complications are more severe and can be dangerous, if "heroic" maneuvers are performed during catastrophic shoulder dystocia. Zavanelli maneuver and symphysiotomy are associated with significant maternal morbidity and mortality.

Neonatal Complications:

Brachial plexus injuries and fractures of the clavicle and humerus are associated with shoulder dystocia. The reported incidence of brachial plexus injuries following a delivery complicated by shoulder dystocia varies widely from 4% to 40%. Fortunately, most cases resolve without permanent disability; that is, fewer than 10% of all cases of shoulder dystocia result in a persistent brachial plexus injury. Some severe cases of shoulder dystocia may result in hypoxic-ischemic encephalopathy and even death.

Brachial Plexus Injury: injury to the brachial plexus may be localized to the upper or lower part of the plexus. It usually results from downward traction on the brachial plexus during delivery of anterior shoulder. Erb palsy results from injury to the spinal nerves C5-6 and sometimes C7. It consists of a paralysis of shoulder and arm muscles resulting in a hanging upper arm that may be extended at the elbow. Involvement of the lower spinal nerves (C7- T1) always includes injury of the upper nerves and results in a palsy including the hand, which can cause a claw-hand deformity.

Clavicular Fracture: such fractures, although at times associated with shoulder dystocia, often occur without any clinical events to suspect them. Investigators have concluded that isolated fractured clavicles are unavoidable, unpredictable, and are of no clinical consequences.

Predictors of Shoulder Dystocia:

The ideal management strategy for shoulder dystocia is prevention. Although fetal macrosomia and maternal diabetes increase the risk of shoulder dystocia, a substantial proportion of cases occur among women who do not have diabetes and among infants with birth weights less than 4,000 g. Maternal obesity is associated with macrosomia, and thus, obese women are at risk for shoulder dystocia. Other antepartum conditions associated with shoulder dystocia include: multiparity; postterm gestation; previous history of shoulder dystocia. Associated intrapartum factors include labor induction, epidural anesthesia, and operative vaginal delivery (forceps and vacuum-assisted delivery).

A policy of planned cesarean delivery for suspected macrosomic fetuses (>4,000) in women who do not have diabetes is not recommended. Ultrasonography is not an accurate predictor of macrosomia. Furthermore, most macrosomic infants do not experience this complication. Consequently, if all fetuses suspected of being macrosomic underwent cesarean delivery, the cesarean delivery rate would increase disproportionately when compared with the reduction in the rate of shoulder dystocia. Although the diagnosis of fetal macrosomia is imprecise, prophylactic cesarean delivery may be considered for suspected fetal macrosomia with estimated fetal weights greater than 5,000 g in women without diabetes and greater than 4,500 g in women with diabetes.

Management of Shoulder Dystocia:

Reduction in the interval of time from delivery of the head to delivery of the body is of great importance to survival. An initial gentle attempt at traction, assisted by maternal expulsive efforts is recommended. Overly vigorous traction on the head or neck, or excessive rotation of the body, may cause serious damage to the infant. Some have advocated performing a large episiotomy, and adequate analgesia is certainly ideal. The next step is to clear the infant's mouth and nose. Having completed these steps, a variety of techniques have been described to free the anterior shoulder from its impacted position beneath the maternal symphysis pubis: (Source: William's Obstetrics, 21st Edition)

  1. Moderate suprapubic pressure is applied by an assistant while downward traction is applied to the fetal head.
  2. The McRoberts maneuver consists of removing the legs from the stirrups and sharply flexing them upon the abdomen. While this does not increase pelvic dimensions, pelvic rotation cephalad tends to free the impacted anterior shoulder.
  3. Woods corkscrew maneuver by progressively rotating the posterior shoulder 180 degrees in a corkscrew fashion, the impacted shoulder could be released.
  4. Delivery of the posterior shoulder consists of carefully sweeping the posterior arm of the fetus across the chest, followed by delivery of the arm. The shoulder girdle is then rotated into one of the oblique diameters of the pelvis with subsequent delivery of the anterior shoulder.
  5. Rubin (1964) recommended two maneuvers: First, the fetal shoulders are rocked from side to side by applying force to abdomen. If this is not successful, the pelvic hand reaches the most easily accessible fetal shoulder, which is pushed toward the anterior surface of the chest. This most often results in abduction of both shoulders. This in turn produces a smaller shoulder-to-shoulder diameter and displacement of the anterior shoulder from behind the symphysis pubis.
  6. Hibbard (1982) recommended that pressure be applied to the fetal jaw and neck in the direction of the maternal rectum, with strong fundal pressure applied by an assistant as the anterior shoulder is freed. Strong fundal pressure applied at the wrong time may result in even further impaction of the anterior shoulder.
  7. Zavanelli maneuver: cephalic replacement into the pelvis and then cesarean delivery. The first part of the maneuver consists of returning the head to the occiput anterior or occiput posterior position if the head has rotated from either position. The second step is to flex the head and slowly push it back into the vagina, following which cesarean delivery is performed. Terbutaline is given to produce uterine relaxation. Fetal injuries, including stillbirths and neonatal brain damage and uterine rupture are high with this maneuver.
  8. Deliberate fracture of the clavicle by pressing the anterior clavicle against the ramus of the pubis can be done to free the shoulder impaction. The fracture heals rapidly and is not nearly as serious as brachial nerve injury, asphyxia, or death.
  9. Cleidotomy consist of cutting the clavicle with scissors or other sharp instruments, and is usually used on a dead fetus.
  10. Symphysiotomy also has been applied successfully. Maternal morbidity was significant due to urinary tract injury.

Trends in Incidence of Maternal and Neonatal Morbidity:

Shoulder dystocia is a highly unpredictable and largely unpreventable event with potentially serious consequences for mother and neonate. It is often managed inappropriately, with suboptimal care having been identified in 66% of perinatal deaths and 46% of cases of brachial plexus injury related to shoulder dystocia. Shoulder dystocia training has been recommended in both the United States and the United Kingdom, and recent evidence suggests that management of simulated shoulder dystocia can be improved by practical training. The American Joint Commission for Accreditation of Healthcare Organizations gives no guidance on frequency of practical training. In the UK, the Clinical Negligence Scheme for Trusts has arbitrarily mandated annual shoulder dystocia training for all staff. The most important aspect of training is ensuring that initial training is effective. The question remains what is optimal interval between training sessions? For those who are initially competent, annual training is probably adequate, but for those who gain proficiency during initial training or with remedial teaching, it would seem prudent to check competency every 3 to 6 months until skill retention is established. Although factors associated with an increased risk of shoulder dystocia are well recognized, our ability to predict these cases remains limited, as do reliable prediction of fetal weight.

Counseling regarding subsequent deliveries with a history of shoulder dystocia:

A history of shoulder dystocia is associated with a recurrence rate ranging from 1% to 16.7%. However, the true incidence may remain unknown because physicians and patients often choose not to attempt a trial of labor when there is a history of complicated delivery or an injured infant. Because most subsequent deliveries will not be complicated by shoulder dystocia, the benefit of universal elective cesarean delivery is questionable in patients who have such a history of shoulder dystocia. Other factors that may aid in the decision-making process for mode of delivery include the present estimate of fetal weight compared with the prior pregnancy birth weight, gestational age, the presence of maternal glucose intolerance, and the severity of the prior neonatal injury. A discussion and review of the prior delivery events should be undertaken with the patient, preferably before the intrapartum period. After discussion with the patient, either method of delivery is appropriate. It is clear that brachial plexus injury can occur regardless of the procedure or procedures used to disimpact the shoulders.

Summary of Recommendations:

Because of the rarity and urgency of shoulder dystocia, many hospitals in the USA have Shoulder Dystocia Drill, to better organize emergency management of an impacted shoulder. The drill is a set of maneuvers performed sequentially as needed to complete vaginal delivery. Ultrasonographic measurements to estimate macrosomia have limited accuracy. Planned cesarean delivery on the basis of suspected macrosomia in the general population is not a reasonable strategy because the number and cost of additional cesarean deliveries required to prevent one permanent injury is excessive. Planned cesarean delivery may be reasonable strategy for diabetic pregnant women with estimated fetal weights exceeding 4,000 g.

Traction combined with fundal pressure has been associated with a high rate of brachial plexus injuries and fractures. There is no evidence that any one maneuver is superior to another in releasing an impacted shoulder or reducing the chance of injury. However, the McRoberts maneuver and suprapubic pressure most of the time easily facilitate and has high success rate without an associated increase in risk of injury to the newborn.

The American College of Obstetricians and Gynecologists recommends the following steps - their sequence will depend on the experience and preference of the individual operator:

  • Call for help - mobilize assistants, an anesthesiologist, and a pediatrician. At this time, an initial gentle attempt at traction is made. Drain the bladder if it is distended.
  • A generous episiotomy (mediolateral or episioproctotomy) may give room posteriorly.
  • Suprapubic pressure is used initially by most practitioners because it has the advantage of simplicity. Only one assistant is needed to provide suprapubic pressure while normal downward traction is applied to the fetal head.
  • The McRoberts maneuver requires two assistants. Each assistant grasps a leg and sharply flexes the maternal thigh against the abdomen.

These maneuvers will resolve most cases of shoulder dystocia. If they fail, however the following steps may be attempted: the Woods cork-screw maneuver, or delivery of the posterior arm. Other techniques like intentional fracture of clavicle and the Zavanelli maneuver generally should be reserved for cases in which all other maneuvers have failed.

A discussion and review of the prior delivery events should be undertaken with the patient, preferably before the intrapartum period. After discussion with the patient, the method of delivery either trial of vaginal delivery or elective cesarean section should be decided.

Suggested Reading:

Dangers of Shoulder Dystocia

  1. National Health Service Litigation Authority: Summary of substandard care in cases in brachial plexus injury. NHSLA Journal 2003;2 suppl:ix-xi
  2. Deering S, Poggi S, Macedonia C et al. Improving resident competency in the management of shoulder dystocia with simulation training. Obstet Gynecol 2004;103:1224-1228
  3. Royal College of Obstetricians and Gynecologists. Towards Safer Childbirth. 1999
  4. ACOG Practice Bulletin. Shoulder dystocia. Number 40, November 2002
  5. Crofts JF, Bartlett C, Ellis D et al. Management of shoulder dystocia, skill retention 6 and 12 months after training. Obstet Gyecol 2007;110:1069-1074
  6. Ouzounian JG, Gherman RB. Shoulder dystocia: are historic risk factors reliable predictors? Am J Obstet Gynecol 2005;192:1933-1935
  7. Irion O, Boulvain M. Induction of labor for suspected fetal macrosomia. Cochrane Database Syst Rev 2000;(2):CD000938
  8. MacKenzie IZ, Shah M, Lean K et al. Management of shoulder dystocia; trends in incidence and maternal and neonatal morbidity. Obstet Gynecol 2007;110:1059-1068

Published: 6 August 2009

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