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Shoulder dystocia: Intrapartum diagnosis, management, and outcome

Shoulder dystocia: Intrapartum diagnosis, management, and outcome
Literature review current through: Sep 2023.
This topic last updated: Jun 06, 2023.

INTRODUCTION — A vaginal birth is complicated by shoulder dystocia when additional obstetric maneuvers beyond gentle traction are needed to enable delivery of the fetal shoulders after expulsion of the head. Few shoulder dystocias can be anticipated and prevented, as most occur in the absence of risk factors. It is an obstetric emergency; thus, the obstetric provider must be able to recognize a shoulder dystocia immediately and proceed through an orderly sequence of steps to accomplish delivery in a timely manner. The goal is to prevent fetal asphyxia and permanent Erb's palsy or death, while avoiding physical injury (eg, fetal fracture, maternal tissue trauma), but the latter is acceptable if needed to prevent permanent injury of the child.

Intrapartum diagnosis and management of shoulder dystocia will be reviewed here. Risk factors for shoulder dystocia and planning delivery of pregnancies at high risk are discussed separately. (See "Shoulder dystocia: Risk factors and planning birth of high-risk pregnancies".)

PATHOPHYSIOLOGY

Normal descent of the shoulders – The head and shoulders are the largest fetal diameters and must go through a sequence of rotational movements to enable descent and expulsion from the birth canal. Normally, the fetal bisacromial diameter (the distance between the outermost parts of the fetal shoulders) enters the pelvic inlet transversely because the transverse diameter of the inlet is its widest diameter. The shoulders eventually rotate to an anterior-posterior position since the widest diameter of the outlet is the anterior-posterior diameter and descend at an oblique angle with the posterior shoulder ahead of the anterior one, which allows the anterior should to slip under the symphysis pubis (figure 1).

Descent in shoulder dystocia – If the bisacromial diameter enters the pelvic inlet in an anterior-posterior position or the shoulders descend simultaneously rather than at an oblique angle with the posterior shoulder leading, the anterior shoulder can become impacted behind the symphysis pubis or descent of the posterior shoulder can be obstructed by the sacral promontory. Anterior obstruction is more common than posterior obstruction.

It is hypothesized that failure of the bisacromial diameter to undergo normal rotation occurs because of resistance between the fetal skin and vaginal walls; resistance of a large fetal chest relative to the biparietal diameter, which may occur with macrosomia; or because of rapid fetal descent, which may occur with precipitous labor [1,2].

Mechanisms of injury – Neonatal injuries diagnosed at birth may be caused by antepartum or intrapartum events [3,4]. For example:

Descent of the fetal head when descent of the anterior or posterior shoulder is obstructed by the bony pelvis can stretch the nerves in the brachial plexus, which may result in nerve injury.

Umbilical cord compression, compression of fetal neck vessels, bradycardia from excessive vagal stimulation, or a combination of factors during shoulder dystocia may result in fetal asphyxia.

The provider's attempt to resolve the dystocia and deliver the fetus may result in traumatic injury.

PREVALENCE — Shoulder dystocia occurs in 0.2 to 3.0 percent of births [5]. The wide variation is due to differences in the prevalence of macrosomia and diabetes among study populations and to the subjective nature of the diagnosis, which is based on the provider's assessment of the difficulty of the delivery. (See 'Diagnosis' below.)

The prevalence of shoulder dystocia has been increasing, probably related to the increasing prevalence of risk factors for high birth weight, such as maternal obesity and diabetes [6,7].

DIAGNOSIS

Clinical criteria — Shoulder dystocia is a subjective clinical diagnosis. It should be suspected when the fetal head retracts into the perineum after expulsion (called the turtle sign) due to reverse traction from the impacted shoulders at the pelvic inlet. The diagnosis is made when the routine practice of gentle, downward traction on the fetal head fails to accomplish delivery of the anterior shoulder.

Severity of shoulder dystocia is also subjective and decided retrospectively based on need for multiple maneuvers to effect delivery and whether or not the fetus and/or the mother sustained injury as a result.

Attempts at objective criteria for diagnosis — A more objective definition would be useful, but none are widely accepted. The most common objective criteria for diagnosis of shoulder dystocia is a head-to-body delivery interval >60 seconds, which was two standard deviations above the mean value (24 seconds) in 210 births that did not necessitate any ancillary obstetric maneuvers (eg, McRoberts position, delivery of the posterior arm, suprapubic pressure) [8]. A head-to-body delivery interval >60 seconds was subsequently found to identify newborns with higher birth weight, lower one-minute Apgar scores, and higher prevalence of birth injury, thus supporting its use as an objective criteria for shoulder dystocia [9]. Although promising, this definition has not been studied extensively and further investigation is needed to validate its use for diagnosis of shoulder dystocia and determine the optimum threshold for predicting adverse neonatal outcomes.

MANAGEMENT

General principles

Shoulder dystocia is an obstetric emergency. The goal of management is to safely deliver the newborn before asphyxia or cortical injury occurs from umbilical cord compression and impeded inspiration, and without causing peripheral neurologic injury or other fetal or maternal trauma.

Shoulder dystocia cannot be accurately predicted by antenatal or intrapartum risk factors, and thus it and its associated complications cannot be consistently avoided (see "Shoulder dystocia: Risk factors and planning birth of high-risk pregnancies"). Therefore, the clinician should be prepared for a shoulder dystocia at all vaginal births and have a step-wise plan for expeditious diagnosis and treatment if it occurs.

In general, the clinician has up to five minutes to deliver a previously well-oxygenated term infant before the risk of asphyxial injury increases [10-12]. The mean umbilical artery pH at term is 7.27; in two studies, umbilical artery pH was estimated to fall 0.01 and 0.04 pH units per minute, respectively, in the interval between delivery of the fetal head and the rest of the body [11,13]. However, in practice, there is a poor correlation between the head-to-body delivery interval and pH, pCO2, base deficit, neonatal encephalopathy, or death [3,5]. (See "Umbilical cord blood acid-base analysis at delivery".)

Clinicians should be familiar with several maneuvers that are effective for delivering the impacted shoulders. Most maneuvers are intended to disimpact the anterior shoulder from behind the symphysis pubis by rotating the fetal trunk or delivering the posterior arm and shoulder.

Initial measures — When shoulder dystocia is suspected, the pregnant person and labor room personnel should be given clear instructions and the following measures should be initiated:

Document the time of diagnosis. Some providers find it useful to designate an individual to announce the passage of time after diagnosis in 60-second increments.

Instruct the patient not to push while preparations are made and maneuvers are undertaken to reposition the fetus.

Call nursing, anesthesia, obstetric, and pediatric staff to the labor room, if not already available, to provide assistance as needed.

Position the patient with their buttocks flush with the edge of the bed to provide optimal access for executing maneuvers to effect delivery.

Release a tight nuchal cord, if present, over the fetal head and leave it intact as umbilical blood flow helps in neonatal resuscitation and transition. Clamping and cutting the cord does not help to release the impacted shoulder. If cutting the cord is necessary to extract the fetus, it should be done after the shoulder dystocia has been resolved.

Clamping and cutting the cord with the head at the perineum is potentially harmful if a Gunn-Zavanelli-O’Leary maneuver is performed since oxygen delivery to the fetus ceases between the time the cord is clamped and cut and the time of birth via cesarean [14-16]. (See 'Gunn-Zavanelli-O'Leary maneuver' below.)

Avoid excessive downward traction, greater than usual head and neck traction, and fundal pressure because this combination of maneuvers can stretch and injure the brachial plexus and rupture the uterus [3,17-20]. We agree with American College of Obstetricians and Gynecologists' guidance to apply axial traction in alignment with the fetal cervicothoracic spine with a downward component along a vector no more than 45 degrees below the horizontal plane when the laboring patient is in a lithotomy position [5].

Although some downward traction on the fetal neck is necessary to release the anterior shoulder, forceful and excessive downward traction alone should be avoided because it further impacts the shoulders and can increase the risk of fetal injury. The potential harm of forceful downward traction is well-accepted and based on clinical experience and biologic plausibility, but published data are limited. A retrospective study reported four cases of shoulder dystocia managed with forceful downward traction on the fetal neck alone: three were associated with brachial plexus injury and one had a clavicular fracture [20].

Clinicians should think about whether they are applying greater than normal force to deliver the shoulders, and if they perceive this is the case, then this perception should prompt utilization of maneuvers to resolve the dystocia. After releasing the shoulder, normal traction will allow delivery of the infant. A study using force-sensing devices on 29 randomly selected vaginal births found that clinician-applied peak forces are approximately 47 Newtons (N) for routine deliveries, 69 N for difficult deliveries, and 100 N for shoulder dystocia deliveries [21]. In one case, fracture of the clavicle occurred at peak force of approximately 100 N, and appeared to be related to applying a high peak force quickly rather than gradually and for applying it for a prolonged period of time (over 30 seconds). However, measuring traction forces during shoulder dystocia management is not practical.

Consider performing a mediolateral episiotomy, which may be useful to facilitate delivery of the posterior shoulder and other internal procedures, but does not by itself help to release the anterior shoulder and increases perineal trauma [22]. If the perineum was not adequately surgically incised or lacerated with expulsion of the fetal head, cutting or extending the existing mediolateral or median episiotomy/laceration immediately following failed downward traction with and without McRoberts maneuver and before attempting any of the vaginal maneuvers for resolution of the dystocia is a practical approach. (See "Approach to episiotomy", section on 'Complications'.)

Drain a distended bladder, if present, which will facilitate suprapubic pressure and may reduce any space-occupying effects of a full bladder in the vagina.

Choosing maneuvers for releasing the impacted shoulder — Since further descent of the fetal shoulder is prevented by the maternal pelvic bones, increasing traction is counterproductive and maneuvers to release the impacted shoulder are needed to resolve the dystocia [23]. This is the author's typical approach:

Perform McRoberts maneuver – The author performs the McRoberts maneuver first without and then with suprapubic pressure as the initial approach for releasing the impacted shoulder, given that it is less invasive than other maneuvers. (See 'McRoberts maneuver' below and 'McRoberts maneuver with suprapubic pressure' below.)

Deliver the posterior arm – If the McRoberts maneuver with suprapubic pressure is unsuccessful, the author delivers the posterior arm. Some authorities suggest beginning with delivery of the posterior arm because of its high success rate, even though it is a more invasive approach [24]. (See 'Delivery of the posterior arm' below.)

Apply axial traction to deliver the posterior shoulder – If it is not possible to reach the elbow or forearm because the posterior arm is above the pelvic brim, the author attempts to deliver the posterior shoulder via the axilla, which almost always enables resolution of the dystocia. (See 'Axillary traction for delivery of the posterior shoulder' below.)

Try to rotate the shoulders – If the above maneuvers are unsuccessful, the author performs a rotational maneuver (eg, Woods, Rubin). (See 'Rubin maneuver' below and 'Woods screw maneuver' below.)

Fracture the clavicle – In the rare cases where shoulder dystocia persists at this stage, the author fractures the clavicle. (See 'Clavicular fracture' below.)

This approach may vary depending upon the clinical situation, clinician preference, accessibility of assistants, and availability of anesthesia. For example, in a patient with severe obesity, the author may omit adding suprapubic pressure to the McRoberts maneuver. Or if another obstetric provider has tried to manage a shoulder dystocia, but is unsuccessful, and the author is called to help with the emergency, he usually immediately attempts to deliver the posterior arm as this maneuver is often successful and avoids more traction on the fetal head and brachial plexus.

There are no randomized trials comparing results from use of the various maneuvers. The general consensus is that no maneuver is clearly superior for resolving the dystocia and preventing fetal brachial plexus injury [5,25,26], as all maneuvers can increase the degree of stretch on the brachial plexus [27].

It is reasonable to attempt each maneuver a couple of times before quickly moving on to the next maneuver. As more maneuvers are attempted, the likelihood of success increases, but the risk of fetal injury also increases, which may reflect increasingly severe dystocia rather than use of increasingly morbid maneuvers [28,29].

Descriptions of maneuvers for release of impacted shoulders

Initial maneuvers

McRoberts maneuver — The author suggests the McRoberts maneuver as the initial approach for releasing the impacted shoulder because it is less invasive than other maneuvers and often successful, in agreement with the American College of Obstetricians and Gynecologists [5].

Technique – The McRoberts maneuver requires two assistants, each of whom grasps a maternal leg and sharply flexes the thigh back against the abdomen (figure 2) [30]. This procedure relieves shoulder dystocia via marked cephalad rotation of the symphysis pubis and subsequent sacral flattening, thus removing the sacral promontory as an obstruction site (figure 3) [30,31]. In addition, bringing the pelvic inlet into the plane perpendicular to the maximum expulsive force significantly improves pushing efficiency [32]. McRoberts maneuver does not change the actual dimensions of the maternal pelvis.

Success rate – McRoberts position alone has successfully alleviated shoulder dystocia in as many as 42 percent of patients [33]. There is no clear advantage to performing the maneuver before diagnosis of shoulder dystocia; however, evidence is limited as available trials are small and underpowered to detect moderate benefits from prophylactic intervention [34]. On the other hand, there is no disadvantage to performing the maneuver prophylactically in patients at high risk of shoulder dystocia.

Complications – Complications are rare. Excessive force or prolonged placement of the patient's legs in a hyperflexed position has led to maternal complications, such as symphyseal separation, sacroiliac joint dislocation, and transient lateral femoral cutaneous neuropathy, in case reports [35].

McRoberts maneuver with suprapubic pressure — This maneuver is most useful in mild cases of shoulder dystocia and those caused by an impacted anterior shoulder. It requires use of an assistant to apply pressure suprapubically (not fundally) with the palm or fist, directing the pressure on the anterior shoulder both downward (to below the pubic bone) and laterally (toward the fetal face or sternum) in conjunction with the McRoberts maneuver (figure 2). Suprapubic pressure is supposed to adduct the shoulders or bring them into an oblique plane, since the oblique diameter is the widest diameter of the maternal pelvis.

Delivery of the posterior arm — Delivery of the posterior arm almost always relieves impaction of the anterior shoulder and resolves the dystocia [26,36]. It is an appropriate second maneuver if the less technically demanding and often successful McRoberts maneuver and suprapubic pressure fail [26]. Ideally, the patient should have adequate anesthesia.

Technique – A hand is inserted into the vagina to locate the posterior shoulder and arm. If the fetal abdomen faces the maternal right, the operator's left hand is used; if the fetal abdomen faces the maternal left, the right hand is used.

The posterior arm is identified and followed to the elbow. If the elbow is flexed, the operator can grasp the forearm and hand and pull out the arm. If it is extended, pressure is applied in the antecubital fossa. This flexes the elbow across the fetal chest and allows the forearm or hand to be grasped.

The arm is then pulled out of the vagina, which also delivers the posterior shoulder and reduces the shoulder diameter by 2 to 3 cm since the 13 cm bisacromial diameter becomes a 10 to 11 cm axilloacromial diameter (figure 4) [24].

If the anterior shoulder cannot be delivered at this point, the fetus can be rotated and the procedure repeated for the anterior (now posterior) arm.

A similar procedure is followed if the arm is trapped behind the fetus. In this case, manipulating the forearm so it can be swept ventrally and out the vagina may involve deliberate or inadvertent fracture of the humerus.

Complications – The greatest risk with delivery of the posterior arm is humerus fracture, which has been reported in 0 to 20 percent of cases; the risk is highest when used after other maneuvers have failed [20,37-39]. To minimize this risk, it is important to apply pressure at the antecubital fossa to flex the fetal forearm and then sweep it out over the fetal chest, rather than grasping and pulling directly on the arm or mid-humeral shaft.

Axillary traction for delivery of the posterior shoulder — If it is not possible to reach the elbow or forearm because the posterior arm is above the pelvic brim, it may be possible to deliver the posterior shoulder before delivering the arm [40-42].

Technique

After an assistant gently flexes the fetal head toward the anterior shoulder, the operator places their right middle finger into the fetus' posterior axilla from the left side of the pelvis and the left middle finger into the posterior axilla from the right side of the pelvis (Menticoglou maneuver) (figure 5).

The two middle fingers in the axilla are then used to pull the posterior shoulder downward along the curve of the sacrum.

Once the shoulder has been brought down sufficiently, the posterior arm can be grasped and delivered.

Pulling the posterior shoulder into the posterior pelvic space may release the anterior shoulder or allow a rotational maneuver to release the anterior shoulder.

An alternative approach is for the operator to insert their hand into the posterior pelvis, slide the first finger under the axilla and the thumb over the top of the shoulder so that the fingers encircle the shoulder and the tips of the thumb and first finger touch [43].

The second finger is placed alongside the fetal humerus to hold the arm against the body.

Traction is then applied through the axilla along the sacral curve until the posterior shoulder appears over the perineum and the anterior shoulder pivots around the symphysis.

The posterior shoulder is delivered, followed by the anterior shoulder.

This approach was highly successful (>95 percent) as a first maneuver in a series of 119 cases [43].

Complications – These maneuvers may be associated with an increased risk of fracture but do not appear to increase the risk for brachial plexus injury.

Secondary maneuvers

Rubin maneuver — The Rubin maneuver causes adduction of the fetal shoulder so that the shoulders are displaced from the anteroposterior diameter of the inlet, thereby allowing the posterior arm to enter the pelvis [44]. A study using a laboratory birthing simulator showed that the Rubin maneuver required less traction force and resulted in less brachial plexus extension than the McRoberts maneuver [45]. However, it is more invasive than the McRoberts maneuver and less easily performed in patients without anesthesia.

Technique

Under adequate anesthesia, the operator places one hand in the vagina and on the back surface of the posterior fetal shoulder, and then rotates it anteriorly (towards the fetal face). If the fetal spine is on the maternal left, the operator's right hand is used; the left hand is used if the fetal spine is on the maternal right (figure 6).

Alternatively, the Rubin maneuver can be attempted by placing a hand on the back surface of the anterior fetal shoulder, if it is more accessible.

Another approach is to combine the Rubin maneuver on the back of the posterior shoulder with external suprapubic pressure on the front of the anterior shoulder in the opposite direction or with the McRoberts maneuver. Alternatively, the Rubin and Woods (see below) procedures can be combined so that one shoulder is being pushed from the back and the other shoulder is being pushed from the front in the same clockwise or counterclockwise direction. This increases the rotational force on the shoulders.

Woods screw maneuver — Woods likened shoulder dystocia to the "crossed thread" of a bolt into a nut. Although a bolt cannot be forced straight into a nut, it goes through easily when turned repeatedly [46].

Technique – The Woods screw maneuver rotates the fetus by exerting pressure on the anterior, clavicular surface of the posterior shoulder to turn the fetus until the anterior shoulder emerges from behind the maternal symphysis (figure 7).

If the fetal spine is on the maternal left, the operator uses the left hand to push on the clavicle of the posterior arm and rotate the fetus 180 degrees in a counterclockwise direction. The fetal head and neck should not be twisted. If counterclockwise rotation is unsuccessful, clockwise rotation may release the shoulder.

As discussed above, the Woods and Rubin maneuvers can be combined so that one shoulder is being pushed from the front and the other shoulder is being pushed from the back in the same clockwise or counterclockwise direction. This increases the rotational force on the shoulders.

Shoulder shrug variation — The shoulder shrug maneuver is a variation of the Woods screw maneuver [47]. It was described in a report in which its use resolved three cases of dystocia.

Technique – The posterior shoulder is grasped at the axilla using the operator's thumb and index finger in a pincer grip, the axilla is pulled out toward the fetal head to shrug the shoulder, using the opposite hand to hold the head.

The head and shoulder are then rotated together as a unit 180 degrees toward the fetus's face to release the anterior shoulder and resolve the dystocia.

Although experience with the maneuver is limited, it is unlikely to be harmful and might help in cases in which the posterior shoulder is in the pelvis.

Tertiary maneuver

Clavicular fracture — The clavicle can be intentionally fractured to shorten the bisacromial diameter.

Technique – The operator uses their fingers to pull the anterior clavicle outward until it breaks.

Complications – Intentional clavicular fracture can be difficult to perform and can lead to injury of underlying vascular and pulmonary structures. Nevertheless, it is less morbid than the procedures of last resort described below. (See 'Procedures of last resort' below.)

Other maneuvers — The role of the following maneuvers in management of shoulder dystocia is unclear. They are less well studied than the maneuvers described above, but both are supported by some evidence.

Gaskin all-fours maneuver — This maneuver, first introduced by Ina May Gaskin, CPM, places the mother on her hands and knees (all-fours position) (figure 8) [48], but not in the knee-chest position. An alternative is a racing start or "sprinter" position. These positions increase the space in the hollow of the sacrum and take advantage of gravity, which together facilitate delivery by gentle downward traction on the posterior shoulder (the shoulder against the maternal sacrum) or upward traction on the anterior shoulder (the shoulder against the maternal symphysis).

Although not used by most obstetricians, this is one of the initial group of maneuvers used by some midwives and other clinicians, particularly for the mother in a birthing bed with no or only local or pudendal anesthesia. Some providers prefer to use it before attempting to deliver the posterior arm or shoulder since the latter require more technical expertise. Although the available literature on this maneuver is limited, it supports both the efficacy and low morbidity of this simple approach [49-52].

Posterior axilla sling traction (PAST) — If the posterior arm and shoulder cannot be delivered by the methods described above, case reports have described successful outcomes using a sling to exert traction on the posterior shoulder. This technique may be successful when other methods fail because it eliminates the space occupied in the pelvis by the operator's fingers, but may have higher morbidity than other approaches. Until more safety data are available, the author suggests reserving it for cases in which other commonly used techniques have failed.

Technique – A size 12 or 14 French soft suction catheter or urinary catheter is folded into a loop over the operator's index finger and fed through the posterior axilla until the loop can be retrieved with the operator's other index finger.

The loop is then unfolded to create a sling around the posterior shoulder.

The two ends of the sling are clamped and moderate traction is applied to the sling to deliver the shoulder.

The sling can also be used to rotate the shoulders through 180 degrees assisted by counter pressure on the back of the anterior shoulder.

Success rate – In a series of 19 cases managed with this technique, four neonates had transient Erb's palsy and one had permanent Erb's palsy of the anterior arm, and three neonates had posterior arm humerus fractures [53]. Five of the 19 newborns had died in utero.

Procedures of last resort — If shoulder dystocia occurs in a labor room and cannot be resolved by the maneuvers described above, the patient should be moved to an operating room for cesarean birth after the Gunn-Zavanelli-O’Leary maneuver, the abdominal rescue procedure, or symphysiotomy.

Gunn-Zavanelli-O'Leary maneuver — This procedure requires replacement of the fetal head in the pelvis, followed by cesarean birth [54,55].

Technique – Administer terbutaline (0.25 mg subcutaneously) or another uterine relaxant (nitroglycerin 50 mcg intravenously in aliquots of 50 mcg every minute as needed to relax the uterus, to a maximum dose of 250 mcg; an initial bolus of 100 to 200 mcg can be used but increases the risk of hypotension).

Place a fetal scalp electrode to monitor the fetal heart rate. Bradycardia is common from head compression during the maneuver.

Rotate the head back to an occiput anterior position (reversal of restitution).

Flex the head from its extended position and push it as far cephalad as possible using firm pressure with the palm of one hand. The other hand may be used to depress the perineum. This may relieve umbilical cord compression.

If cephalic replacement is successful, the patient is prepared for surgery and cesarean birth is performed.

Success rate – Over 100 such procedures have been reported, mostly in single case reports, with a high rate of success [56].

Abdominal rescue — Abdominal rescue has been described in case reports where classical maneuvers and the Gunn-Zavanelli-O’Leary maneuver were unsuccessful. A low transverse hysterotomy is performed to allow transabdominal manual rotation of the anterior shoulder to the oblique diameter [57,58]. The fetus is then delivered vaginally.

Symphysiotomy — We recommend avoiding symphysiotomy. Symphysiotomy (surgical division of the cartilage of the symphysis pubis) allows the pubic bones to separate, thereby increasing the size of the pelvic opening and relieving the obstruction to delivery [59]. Even in remote areas of resource-limited countries where operating rooms are unavailable, this procedure is rarely if ever used because of significant risk of maternal morbidity and lack of clinician expertise [60]. The procedure, which is also used to release an entrapped fetal head in breech birth, is described separately. (See "Delivery of the singleton fetus in breech presentation", section on 'Head entrapment'.)

DOCUMENTATION — Clear and complete documentation in the medical record is critically important after births complicated by shoulder dystocia. Some examples are shown in the figures (figure 9A-B) and key points are discussed below.

The best estimate of fetal weight (clinical or ultrasound) should be noted on the labor admission physical examination. Although the error in estimated fetal weight at term may be large, documentation confirms that the weight was assessed and thus considered as part of labor and delivery planning.

If a forceps- or vacuum-assisted vaginal birth was attempted, the indication, fetal station, position of the head, instrument used, and time required to effect delivery should be described.

The time the diagnosis of shoulder dystocia was made, how the diagnosis was made, and the position of the head should be described.

Each of the steps taken to resolve the dystocia, the order in which they were taken, and the results, should be described. The elapsed time should be recorded as accurately as possible.

All significant personnel involved, including nurses, anesthesiologists, pediatricians, and other obstetric staff should write their own notes.

Umbilical cord gases (arterial and venous) should be obtained at birth in all shoulder dystocia cases, even if the newborn does not appear to be depressed.

The time the pediatrician and anesthesiologist were called to the delivery should be noted.

Postpartum, the obstetric provider should discuss the events that occurred at delivery with the mother, including an explanation of the problem, the steps taken to correct it, and possible sequelae.

COMPLICATIONS

Infant — Approximately 95 percent of shoulder dystocias were not associated with injury to the newborn, in a large series (n = 2018 cases) [26]. Injury among the remaining newborns was due to trauma, asphyxia, or both. The following types and frequencies of newborn injury have been described in studies including at least 100 cases of shoulder disorder [3,26]. The newborn may have more than one injury.

Transient brachial plexus palsy (3.0 to 16.8 percent)

Clavicular fracture (1.7 to 9.5 percent)

Humerus fracture (0.1 to 4.2 percent)

Permanent brachial plexus palsy (0.5 to 1.6 percent)

Hypoxic-ischemic encephalopathy (0.3 percent [26])

Death (0 to 0.35 percent)

Clavicular and humeral fractures generally have a benign course, with complete recovery and no neurological or orthopedic sequelae [61]. The majority of brachial plexus palsies resolve with conservative therapy, but some children have persistent functional impairment and other associated morbidities (eg, Horner syndrome). The pathogenesis, clinical features, evaluation, management, and prognosis of neonatal brachial plexus palsy are discussed in detail separately. (See "Neonatal brachial plexus palsy".)

It is important to note that neonatal morbidity can occur even when shoulder dystocia is managed appropriately. Although shoulder dystocia is a major risk factor for brachial plexus injury [62], some cases of fractured clavicle or brachial plexus injury are not due to shoulder dystocia or excessive force by the provider. In fact, several series reported antecedent shoulder dystocia in no more than one-half of the cases of brachial plexus injury in infants [62-65]. A prenatal insult was documented in a significant number of affected infants [64,65] and these injuries have been reported following cesarean births [66]. Thus, the forces of labor, fetal position, and maternal pushing may be sufficient to cause excessive traction on the brachial plexus [67,68] and fetal bones [69].

Maternal — The most common serious maternal complications of shoulder dystocia are hemorrhage and fourth-degree lacerations, which occurred in 11 and 3.8 percent of pregnancies, respectively, in one retrospective study [33]. (See "Overview of postpartum hemorrhage" and "Evaluation and management of female lower genital tract trauma" and "Fecal and anal incontinence associated with pregnancy and childbirth: Counseling, evaluation, and management".)

Additional complications that occur rarely and are most likely related to provider maneuvers to relieve dystocia include maternal symphyseal separation, lateral femoral cutaneous neuropathy, cervicovaginal lacerations, urethral injury, bladder laceration, and uterine rupture [33,70-73].

REDUCING THE RISK OF COMPLICATIONS

Drills (simulation training) — In the United States, The Joint Commission recommends that obstetric departments consider periodically conducting clinical drills to help staff prepare for shoulder dystocia, conduct debriefings to evaluate team performance, and identify areas for improvement [74]. Such drills appear to improve recognition and management of shoulder dystocia, and there is evidence of improvement in neonatal outcome. (See "Reducing adverse obstetric outcomes through safety sciences", section on 'Shoulder dystocia'.)

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Shoulder dystocia and macrosomia".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5th to 6th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10th to 12th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

Basics topics (see "Patient education: Shoulder dystocia (The Basics)")

SUMMARY AND RECOMMENDATIONS

Definition and prevalence: Shoulder dystocia is defined as failure of the shoulders to spontaneously traverse the pelvis after delivery of the fetal head. It occurs in 0.2 to 3 percent of births. (See 'Introduction' above and 'Prevalence' above.)

Prediction and preparation: The occurrence of shoulder dystocia cannot be accurately predicted on the basis of antenatal risk factors or labor abnormalities. Therefore, the clinician should be prepared for possible shoulder dystocia in all vaginal deliveries and familiar with the various procedures that have been shown to be effective for delivering the impacted shoulders. (See 'General principles' above.)

Management

Shoulder dystocia is an obstetric emergency. The goal of management is to prevent fetal asphyxia, permanent brachial plexus palsy, or death, while avoiding fetal or maternal physical injury. However, treatable traumatic injuries (eg, fetal clavicular or long bone fracture, maternal genital tract laceration) are acceptable if warranted to prevent permanent injury in the child. (See 'General principles' above.)

No randomized trials have compared results from use of the various maneuvers to manage shoulder dystocia. The general consensus is that no maneuver is clearly superior for resolving the dystocia and preventing neurologic injury, and that all maneuvers can increase the degree of stretch on the brachial plexus, resulting in brachial plexus injury. (See 'Choosing maneuvers for releasing the impacted shoulder' above.)

Our general approach to shoulder dystocia is described in the table (table 1).

-Initial steps in management include having the patient stop pushing, ensuring proper patient position, assembling necessary personnel, and draining a distended bladder. (See 'Initial measures' above.)

-We suggest the McRoberts maneuver without and then with suprapubic pressure as the initial approach for releasing the impacted shoulder, given that it is less invasive than other maneuvers (Grade 2C). (See 'McRoberts maneuver' above.)

-If the McRoberts maneuver with suprapubic pressure is unsuccessful, we suggest delivery of the posterior arm (Grade 2C). (See 'Delivery of the posterior arm' above.)

-If it is not possible to reach the elbow or forearm, we attempt to deliver the posterior shoulder by pulling on the axilla to bring it down into the posterior pelvic space. This may release the anterior shoulder, or allow access to the elbow or forearm so that the posterior arm can be delivered, or allow a rotational maneuver to release the anterior shoulder. (See 'Axillary traction for delivery of the posterior shoulder' above.)

-If the above maneuvers are unsuccessful, we perform a rotational maneuver (Woods, Rubin). (See 'Rubin maneuver' above and 'Woods screw maneuver' above.)

The Gaskin all-fours maneuver may be a good initial choice for the mother in a birthing bed with no or only local or pudendal anesthesia. Some providers prefer to use it before attempting to deliver the posterior arm or shoulder as the latter require more technical proficiency. (See 'Gaskin all-fours maneuver' above.)

Documentation: Clear and complete documentation in the medical record is critically important after deliveries complicated by shoulder dystocia (figure 9A-B). (See 'Documentation' above.)

Prevention: No clear advantage to performing the McRoberts maneuver before diagnosis of shoulder dystocia has been documented; however, evidence is limited as available trials are small and underpowered to detect moderate benefits from prophylactic intervention. There is no harm in employing the maneuver prophylactically in patients at high risk of shoulder dystocia. (See 'McRoberts maneuver' above.)

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