Shoulder Dystocia

Aka: Shoulder Dystocia, Impacted Shoulders During Labor

1. Also See
   1. Fetal Macrosomia
   2. Gestational Diabetes
2. Definitions
   1. Shoulder Dystocia
      1. Birth complication in which the fetal anterior Shoulder impacts the maternal Symphysis Pubis and prevents fetal body delivery
      2. Potentially life-threatening condition requiring emergent maneuvers to relieve the impaction and deliver the fetal body
3. Epidemiology
   1. Incidence of Shoulder Dystocia
      1. Incidence Overall: 0.3 - 1% of vaginal deliveries
      2. Birthweight >4000g: 5-7%
      3. Birthweight >4500g: 8-10%
   2. Shoulder Dystocia Cases by birthweight
      1. Infants over 4500 grams: 50%
      2. Infants 4000 to 4500 grams: 23%
      3. Infants 3500 to 4000 grams: 9%
      4. Normal birthweight infant: 50-66% in some studies
4. Risk Factors
   1. Most cases occur without obvious predictors
   2. Assisted Vaginal Delivery (most common risk factor)
   3. Fetal Macrosomia (>4000 grams, OR>16)
      1. Estimated fetal weight of current pregnancy
      2. Prior macrosomic infant
      3. Family History of Fetal Macrosomia
   4. Gestational Diabetes
   5. Multiparity
   6. Postterm delivery
   7. Maternal abnormal Pelvic Anatomy, Short Stature or Obesity
   8. History of prior Shoulder Dystocia (OR>8)
   9. Prolonged first or second stage of labor
   10. Oxytocin use to augment labor
   11. Operative Vaginal Delivery (vacuum or forceps)
5. Signs: Warning signs suggestive of Shoulder Dystocia
   1. Prolonged second stage of labor
   2. Recoil of head on perineum (turtle's sign)
6. Diagnosis
   1. Time between delivery of head and delivery of body >60 seconds
   2. Additional delivery maneuvers required to deliver the body
7. Management
   1. See Shoulder Dystocia Management
8. Complications: Shoulder Dystocia Fetal Effects
   1. Brachial Plexus Injury from Birth Trauma (10%)
      1. General
         1. Most resolve in first year, but persistent in 10% of cases
         2. Palsy may be unrelated to disimpaction maneuvers
            1. Gherman (1998) Am J Obstet Gynecol 178:423-7 [PubMed]
            2. Sandmire (2000) Am J Obstet Gynecol 95:941-2 [PubMed]
      2. Types
         1. Erb-Duchenne Palsy
            1. Fifth and sixth cervical roots
         2. Klumpke's Paralysis
            1. Eighth cervical and first thoracic roots
   2. Fractures
      1. Humerus Fracture
      2. Clavicle Fracture from Birth Trauma
   3. Fetal Asphyxia and Fetal hypoxic ischemic encephalopathy
   4. Fetal Death
   5. Meconium Aspiration
9. Complications: Shoulder Dystocia Maternal Effects
   1. Postpartum Hemorrhage (11% of cases)
   2. Fourth-degree perineal Laceration (Up to 4% of cases)
   3. Lacerations to other pelvic structures (Bladder, Urethra, vagina, anal sphincter, Rectum)
   4. Uterine Rupture
   5. Rectovaginal fistula
   6. Pubic Symphysis separation
   7. Lateral Femoral Cutaneous Neuropathy
10. Prognosis
    1. Shoulder Dystocia results in cord compression
       1. Arterial pH drops 0.04 per minute
       2. Arterial pH drops 0.28 in seven minutes
       3. Arterial pH drops 0.14 per minute on trunk delivery
    2. Arterial pH below 7.0 makes Resuscitation difficult
11. Prevention: Anticipation of a Shoulder Dystocia
    1. Advanced Life Support in Obstetrics (ALSO) course
       1. https://www.aafp.org/cme/programs/also.html
       2. Prepares providers for obstetrical emergencies including Shoulder Dystocia Management
    2. During delivery
       1. Deliver at the start of the contraction
       2. Deliver head and Shoulders with the same push
       3. Suction airway after Shoulders are delivered
    3. Cesarean delivery for fetal macrosmia indications
       1. ACOG recommends considering cesarean delivery for fetal weight >5000 g (11 lb)
       2. ACOG recommends considering cesarean delivery for Gestational Diabetes AND weight >4500 g (9 lb 15 oz)
       3. (2017) Obstet Gynecol 129(5): e123-33
    4. However, prior studies did not show benefit for induction or cesarean in macrosomia
       1. See Fetal Macrosomia
       2. Elective cesarean does not reduce dystocia cases
          1. Rouse (1996) JAMA 276:1480-6 [PubMed]
       3. Early induction does not reduce dystocia cases
          1. Kjos (1993) Am J Obstet Gynecol 169:611-5 [PubMed]
12. References
    1. Acker (1986) Obstet Gynecol 67:614-8 [PubMed]
    2. Baskett (1995) Obstet Gynecol 86:14-7 [PubMed]
    3. Baxley (2004) Am Fam Physician 69:1707-14 [PubMed]
    4. Hill (2020) Am Fam Physician 102(2): 84-90 [PubMed]
    5. Lewis (1995) Am J Obstet Gynecol 172:1369-71 [PubMed]