Shoulder Dystocia

Aka: Shoulder Dystocia, Impacted Shoulders During Labor

1. Also See
   1. Fetal Macrosomia
   2. Gestational Diabetes
2. Epidemiology
   1. Incidence of Shoulder Dystocia
      1. Incidence Overall: 0.3 - 1%
      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
3. Risk Factors
   1. Most cases occur without obvious predictors
   2. Assisted Vaginal Delivery (most common risk factor)
   3. Fetal Macrosomia (>4000 grams)
      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 or Short Stature
   8. History of prior Shoulder Dystocia
   9. Prolonged first or second stage of labor
4. Signs: Warning signs suggestive of Shoulder Dystocia
   1. Prolonged second stage of labor
   2. Recoil of head on perineum (turtle's sign)
5. Management
   1. See Shoulder Dystocia Management
6. Complications: Shoulder Dystocia Fetal Effects
   1. Brachial Plexus Injury from Birth Trauma (10%)
      1. General
         1. Most resolve in first year, some persistent
         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. Clavicle Fracture
      2. Humerus Fracture
   3. Fetal Asphyxia
   4. Fetal Death
   5. Meconium Aspiration
7. Complications: Shoulder Dystocia Maternal Effects
   1. Postpartum Hemorrhage (11% of cases)
   2. Fourth-degree perineal Laceration (Up to 4% of cases)
   3. Uterine Rupture
   4. Rectovaginal fistula
   5. Pubic Symphysis separation with femoral Neuropathy
8. 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
9. Prevention: Anticipation of a Shoulder Dystocia
   1. Deliver at the start of the contraction
   2. Deliver head and Shoulders with the same push
   3. Suction airway after Shoulders are delivered
   4. Early induction or cesarean in macrosomia not supported
      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]
10. 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. Lewis (1995) Am J Obstet Gynecol 172:1369-71 [PubMed]