Shoulder dystocia occurs when one or both of the fetal shoulders get wedged against the maternal pelvis, thus requiring maneuvers to deliver the baby (see Picturing shoulder dystocia). Shoulder dystocia is usually caused by the impaction of the anterior shoulder on the bony pubic symphysis or, less commonly, from the posterior shoulder on the sacral promontory of the maternal pelvis.
About 0.2% to 3.0 % of all births result in shoulder dystocia. The definition of shoulder dystocia varies from whether maneuvers were used or the head-to-body time interval was greater than 60 seconds. Over the last few decades, the incidence of shoulder dystocia has increased, most likely due to increasing birth weights and better reporting.
For obstetric care providers and nurses, shoulder dystocia is one of the most dreaded and anxiety-provoking obstetric emergencies. The obstetric care team needs to immediately recognize shoulder dystocia, stay calm, and take a systematic approach to minimize maternal and fetal sequelae. It's important to be aware of what risk factors contribute to shoulder dystocia; what the complications are; how it's diagnosed; and what interventions are needed to provide the best care for your patient before, during, and after delivery.
This article reviews shoulder dystocia and the maneuvers used to manage it.
Shoulder dystocia is an obstetric emergency that can cause umbilical cord compression in the birth canal, leading to hypoxemia and acidosis. It can cause significant morbidity and life-threatening neonatal injuries, even when managed appropriately. Neonatal complications resulting from shoulder dystocia include neurologic injuries (such as brachial plexus injury, diaphragmatic paralysis, facial nerve injuries, and Horner syndrome), fracture of the clavicle or humerus, fetal hypoxic ischemic encephalopathy, and even fetal death. Neonatal brachial plexus palsy is one of the most common injuries and generally resolves spontaneously. However, proper management during shoulder dystocia may not prevent all brachial plexus injuries, which can result from other causes.
Postpartum hemorrhage from atony or lacerations is one of the most common maternal complications of shoulder dystocia. Additionally, lacerations of the bladder, urethra, vagina, or anal sphincter and uterine rupture can occur. Less common maternal injuries include femoral neuropathy and symphyseal separation. Shoulder dystocia can have psychological effects, such as posttraumatic stress disorder, for both the patient and the healthcare provider. Shoulder dystocia is also a major cause of litigation in obstetrics, which may result in a management approach with more interventions and a higher rate of cesarean birth.
Can it be predicted or prevented?
Shoulder dystocia is usually unpredictable and unpreventable, but there are risk factors that can be divided into maternal, fetal, or labor-related factors. Significant risk factors include fetal macrosomia, previous shoulder dystocia, and preexisting or gestational diabetes mellitus.
Although there's much debate about what defines macrosomia, in general it's when a fetus is larger than average (between 4,000 g [8 lb, 13 oz] and 4,500 g [9 lb, 15 oz]) regardless of gestational age. Fetal macrosomia is a significant risk factor for shoulder dystocia; as birth weight increases, so does the risk. However, fetal weight is difficult to accurately predict.
A higher risk of macrosomia is associated with postterm pregnancy (beyond 42 weeks' gestation or 14 days past the estimated date of delivery), obesity, multiparity, and diabetes. In a woman who develops gestational diabetes, the extra maternal glucose in the bloodstream crosses the placenta and can result in macrosomia associated with a disproportionately larger body-to-head size. A previous birth with shoulder dystocia increases the risk of recurrence to approximately 10%.
Although these factors are known to increase the risk of shoulder dystocia, most cases of shoulder dystocia present with no known risk factors. Therefore, most cases can't be accurately predicted and prevented. Some have suggested having a good diet and exercising can help minimize the risk of macrosomia. For pregnancies complicated by diabetes, controlling maternal hyperglycemia can help reduce the risk of macrosomia. However, induction of labor isn't recommended to prevent shoulder dystocia because the research is inconsistent.
The American College of Obstetricians and Gynecologists (ACOG) recommends a cesarean section if the fetus is larger than 4,500 g (9 lb, 15 oz) and the mother has diabetes or if the fetus is larger than 5,000 g (11 lb) and the mother doesn't have diabetes. Currently, there's no model to accurately predict shoulder dystocia; however, obstetric care team members should be familiar with the risk factors, which can be used to better prepare for deliveries that are more likely to have shoulder dystocia.
Recognizing shoulder dystocia
Timely recognition and accurate management of shoulder dystocia are critical to reduce maternal and fetal complications. Shoulder dystocia is defined by a delay in the delivery of the shoulders following the delivery of the head. A birth that may seem prolonged can be an associated finding.
Signs that aid in the diagnosis of shoulder dystocia include the following:
- birth isn't accomplished with gentle downward traction on the fetal head
- the fetal head retracts back into the perineum and the neck is no longer visible, creating an appearance of a double chin (known as turtle sign)
- failure of restitution of the fetal head (In a normal birth, the head will rotate to the side but with shoulder dystocia, it may stay faced down.)
- difficulty with delivery of face and chin
- failure of the shoulders to descend.
Prompt management by an interdisciplinary team will most likely result in the best outcomes. Reducing the time interval from delivery of the head to delivery of the body is critical.
Anticipation of and initial steps in response to shoulder dystocia
Although most incidents of shoulder dystocia are unpredictable, if there's a suspicion of potential shoulder dystocia, all team members should be made aware of this possibility and a step stool should be placed in the room to provide a better angle for performing suprapubic pressure. Resuscitation equipment and personnel should be ready. An OR provides an ideal location for delivery because equipment is available and accessible in case of an emergency cesarean section. A distended bladder should be drained before the mother delivers to prevent injury and allow more room in the pelvis.
Once shoulder dystocia is identified, a calm, controlled, methodical response is needed. Checklists, algorithms, or protocols can provide a cognitive aid to this approach. Obstetric care providers need to communicate the diagnosis to team members. Gathering additional help is required to activate an emergency response, including additional obstetrics, nursing, anesthesia, pediatrics, and neonatal intensive care staff. Roles such as timekeeper, recorder, and patient/family communicator should be assigned. Team members should call out fetal condition, number of minutes that have passed in 30-second increments, and maneuvers attempted during the episode.
Once the obstetric care provider has identified shoulder dystocia, the first immediate step is to have the mother stop pushing to prevent further impaction of the fetal shoulder. The obstetric care team will initiate maneuvers. These maneuvers are classified as first-line, second-line, and extraordinary or desperation maneuvers.
The obstetric care provider will continually evaluate the success of the maneuvers and determine the next course of action, with the goal of reducing head-to-body delivery time and avoiding fetal and maternal injury from the maneuvers. If the shoulder dystocia lasts longer than 5 minutes, the risk of acidosis and hypoxic ischemic encephalopathy increases significantly. Vigorous traction or twisting on the head or neck can cause serious damage to the fetus. Fundal pressure shouldn't be applied because it further impacts the shoulder, has the potential to injure the fetus, and may result in uterine rupture. Clamping and cutting of the umbilical cord should be avoided until the shoulder dystocia has been resolved.
First-line maneuvers. The ACOG recommends that the McRoberts maneuver be used first, followed by applying suprapubic pressure (see A closer look at the McRoberts maneuver and suprapubic pressure). Both of these maneuvers are noninvasive, easy to perform, and effective. Attention should be given to ensuring that the mother is in an ideal position for these maneuvers.
Second-line maneuvers. There are numerous mnemonics that aid in systematic management of shoulder dystocia. However, there are no randomized controlled studies that compare the different maneuvers. The ACOG suggests that there's no superior maneuver for releasing the impacted shoulder and reducing complications. According to the ACOG, if the McRoberts maneuver and suprapubic pressure measures aren't successful, then extraction of the posterior arm should be considered because it has a high degree of success. This is when the elbow is flexed and the forearm is brought across the chest until the posterior arm is extracted. Careful attention must be paid to not grasp the upper arm because this may fracture the humerus.
Previously, it was recommended that an episiotomy be performed when faced with shoulder dystocia. This is no longer suggested but can be performed to allow extra room for the obstetric care provider to perform internal maneuvers. Because shoulder dystocia isn't a soft tissue concern, an episiotomy won't relieve the obstruction on the bony pelvis. An episiotomy also increases the risk of third- and fourth-degree lacerations.
There are several rotational procedures that can be employed, such as the Woods screw maneuver, Rubin maneuver, Gaskin maneuver, and Menticoglou maneuver. Obstetric care providers need to understand fetal position to successfully employ internal maneuvers. Fundal pressure is no longer recommended with these maneuvers because it can further impact the shoulder and is associated with uterine rupture.
With the Woods screw maneuver (also called Woods corkscrew), the posterior shoulder is rotated in a corkscrew manner 180 degrees to release the impacted anterior shoulder from the maternal symphysis. This maneuver abducts or extends the posterior shoulder.
With the Rubin maneuver, the obstetric care provider inserts fingers behind the most accessible shoulder and pushes the shoulder to rotate it toward the fetal chest. This motion will reduce the fetal shoulder diameter by adducting the fetal shoulder. The Rubin maneuver can be combined with suprapubic pressure. The Woods screw maneuver can be combined simultaneously with the Rubin maneuver to rotate the shoulders. This helps increase the rotational force of the shoulder similar to a bolt being threaded by a nut.
With the Gaskin maneuver, the mother is rolled on her hands and knees (or “all fours” position) to help dislodge the shoulder by increasing the pelvic diameters and gravitational forces. Downward traction is applied to deliver the posterior shoulder. It may be difficult to perform this maneuver if the mother has decreased mobility from an epidural.
With the Menticoglou maneuver, the obstetric care provider places the middle fingers under the posterior fetal axilla and applies downward and outward traction that leads to delivery of the posterior shoulder, which is then followed by delivery of the posterior arm. An assistant is required to support the fetal head and flex toward the anterior shoulder.
Posterior axilla sling traction is another technique that can be used to relieve shoulder dystocia when standard maneuvers haven't worked. A double-looped sling using a suction catheter or urinary catheter is inserted under the posterior fetal axilla. Traction is then exerted on the sling to deliver the posterior shoulder.
Desperation maneuvers. When first- and second-line maneuvers are unsuccessful after several attempts, desperation maneuvers should be employed. These should be considered a last resort because of their high incidence of neonatal morbidity and mortality and maternal morbidity.
Although it isn't uncommon to have a spontaneous fracture of the clavicle, the obstetric care provider can intentionally fracture the clavicle. This procedure reduces the diameter of the shoulders, freeing the impacted shoulder. However, it has a high risk of brachial plexus injury and is difficult to perform.
With abdominal rescue, a laparotomy and hysterotomy are performed, allowing for manual pressure of the anterior shoulder from above, which facilitates a vaginal birth.
Another last-ditch approach is the Zavanelli maneuver, in which the replacement of the fetal head back into the vagina is then followed by an emergency cesarean section. A tocolytic is given to reduce uterine contractions. The operating team must be ready before cephalic replacement is attempted. The Zavanelli maneuver should be done only after all other possible maneuvers have been attempted because it has a significant potential for fetal and maternal complications.
After the birth
Once the birth occurs, there's a significant risk of postpartum hemorrhage and third- and fourth-degree perineal tears. Assessment of the mother's uterus and bleeding is required. The nurse should monitor for excessive blood loss from uterine atony, lacerations, and hematomas. The newborn should be examined by a pediatric provider for evaluation of birth injuries.
Shoulder dystocia is one of the top reasons for litigation in obstetrics. The ACOG has a patient safety checklist to improve documentation of shoulder dystocia and help facilitate the evidence-based standardization of care. Accurate information is critical for healthcare providers to counsel women about future risks.
Important information to include in the documentation of shoulder dystocia includes the following:
- assessment of antepartum risk factors
- gestational age
- estimated fetal weight on admission
- induction or augmentation of labor with oxytocin
- mode of delivery
- time of delivery for the fetal head and time of the complete expulsion of the body
- time that shoulder dystocia was recognized and help called
- what maneuvers were used
- fetal position
- description of fetal heart rate if it was obtainable
- Apgar score and blood gases of the newborn
- maternal or infant complications
- names of the staff members and family who were present at the birth.
Recognition of shoulder dystocia coupled with proper team interventions is necessary for timely delivery of the newborn. Effective interdisciplinary communication and good leadership are essential to provide quality care. Because shoulder dystocia is an infrequent event, simulation and team drills can improve team member skills, such as communication and maneuvers, in a safe environment without the potential to cause patient harm. The Joint Commission and the ACOG recommend team drills to prepare perinatal staff for shoulder dystocia and debriefings after an event to improve team performance.
Shoulder dystocia can have major complications for both the mother and fetus. Nurses play an important role in the interventions to alleviate shoulder dystocia and can be instrumental in providing quality interdisciplinary care and improving outcomes. Accurate documentation is critical due to the risk of litigation and the need to counsel patients about future births. Although shoulder dystocia strikes anxiety in the most experienced healthcare providers, staying calm will help nurses provide a deliberate, systematic response.
Risk factors for shoulder dystocia
- Abnormal pelvic anatomy
- Postterm pregnancy
- Previous shoulder dystocia
- Short stature
- Obesity and excessive gestational weight gain
- Advanced age
- Lack of prenatal care
- Assisted vaginal delivery (forceps or vacuum)
- Male sex
- First-stage abnormalities
- Prolonged second stage
- Induction of labor
- Oxytocin augmentation
- Precipitous birth
- Epidural analgesia
A closer look at the McRoberts maneuver and suprapubic pressure
- Rotation of the pelvis helps free the impacted shoulder.
- Remove pillows and lower the head of the bed so the mother is flat in the supine position. Hyperflex the legs against the abdomen and bring the knees toward her ears.
- This maneuver is best carried out with two assistants, each one holding and hyperflexing a leg.
- Abduction and rotation of the anterior shoulder decreases the diameter of the shoulders going under the symphysis pubis.
- Firm and steady downward and lateral pressure is applied above the pubic bone with the palm or fist to the posterior aspect of the anterior shoulder. For example, if the fetus is facing the mother's right side, suprapubic pressure is applied to her left suprapubic region, down and toward the right.
- This is best done with a nurse standing on a step stool so he or she is above the mother.
- Don't apply fundal pressure because it will cause the shoulder to get further impacted and can lead to uterine rupture.
- Begin with continuous pressure. If this is unsuccessful, a rocking motion is then used.
- The patient's bladder should be emptied to prevent bladder trauma and impediment of the shoulder.
Maneuvers used to manage shoulder dystocia
Woods screw maneuver
Posterior axilla sling traction
Intentional fracture of the clavicle
on the web
American College of Nurse Midwives:www.midwife.org
American College of Obstetricians and Gynecologists:www.acog.org
March of Dimes:www.marchofdimes.org/complications/shoulder-dystocia.aspx
World Health Organization:https://extranet.who.int/rhl/resources/videos/steps-overcome-shoulder-dystocia
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