II. Definitions
- Shoulder Dystocia
- Birth complication in which the fetal anterior Shoulder impacts the maternal Symphysis Pubis and prevents fetal body delivery
- Potentially life-threatening condition requiring emergent maneuvers to relieve the impaction and deliver the fetal body
III. Epidemiology
-
Incidence of Shoulder Dystocia
- Incidence Overall: 0.3 - 1% of vaginal deliveries
- Birthweight >4000g: 5-7%
- Birthweight >4500g: 8-10%
- Shoulder Dystocia Cases by birthweight
- Infants over 4500 grams: 50%
- Infants 4000 to 4500 grams: 23%
- Infants 3500 to 4000 grams: 9%
- Normal birthweight infant: 50-66% in some studies
IV. Risk Factors
- Most cases occur without obvious predictors
- Assisted Vaginal Delivery (most common risk factor)
-
Fetal Macrosomia (>4000 grams, OR>16)
- Estimated fetal weight of current pregnancy
- Prior macrosomic infant
- Family History of Fetal Macrosomia
- Gestational Diabetes
- Multiparity
- Postterm delivery
- Maternal abnormal Pelvic Anatomy, Short Stature or Obesity
- History of prior Shoulder Dystocia (OR>8)
- Prolonged first or Second Stage of Labor
- Oxytocin use to augment labor
- Operative Vaginal Delivery (vacuum or forceps)
V. Signs: Warning signs suggestive of Shoulder Dystocia
- Prolonged Second Stage of Labor
- Recoil of head on perineum (turtle's sign)
VI. Diagnosis
- Time between delivery of head and delivery of body >60 seconds
- Additional delivery maneuvers required to deliver the body
VII. Management
VIII. Complications: Shoulder Dystocia Fetal Effects
-
Brachial Plexus Injury from Birth Trauma (10%)
- General
- Most resolve in first year, but persistent in 10% of cases
- Palsy may be unrelated to disimpaction maneuvers
- Types
- Erb-Duchenne Palsy
- Fifth and sixth cervical roots
- Klumpke's Paralysis
- Eighth cervical and first thoracic roots
- Erb-Duchenne Palsy
- General
- Fractures
- Fetal Asphyxia and Fetal hypoxic ischemic encephalopathy
- Fetal Death
- Meconium Aspiration
IX. Complications: Shoulder Dystocia Maternal Effects
- Postpartum Hemorrhage (11% of cases)
- Fourth-degree perineal Laceration (Up to 4% of cases)
- Lacerations to other pelvic structures (Bladder, Urethra, vagina, anal sphincter, Rectum)
- Uterine Rupture
- Rectovaginal fistula
- Pubic Symphysis separation
- Lateral Femoral Cutaneous Neuropathy
X. Prognosis
- Shoulder Dystocia results in cord compression
- Arterial pH drops 0.04 per minute
- Arterial pH drops 0.28 in seven minutes
- Arterial pH drops 0.14 per minute on trunk delivery
- Arterial pH below 7.0 makes Resuscitation difficult
XI. Prevention: Anticipation of a Shoulder Dystocia
- Advanced Life Support in Obstetrics (ALSO) course
- https://www.aafp.org/cme/programs/also.html
- Prepares providers for obstetrical emergencies including Shoulder Dystocia Management
- During delivery
- Cesarean delivery for fetal macrosmia indications
- ACOG recommends considering cesarean delivery for fetal weight >5000 g (11 lb)
- ACOG recommends considering cesarean delivery for Gestational Diabetes AND weight >4500 g (9 lb 15 oz)
- (2017) Obstet Gynecol 129(5): e123-33
- However, prior studies did not show benefit for induction or cesarean in macrosomia
- See Fetal Macrosomia
- Elective cesarean does not reduce dystocia cases
- Early induction does not reduce dystocia cases