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Shoulder Dystocia

Also See
1. Fetal Macrosomia
2. Gestational Diabetes
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
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
Signs: Warning signs suggestive of shoulder dystocia
1. Prolonged second stage of labor
2. Recoil of head on perineum (turtle's sign)
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
Complications of Shoulder Dystocia: Fetus
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
      2. Sandmire (2000) Am J Obstet Gynecol 95:941
  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
Complications of Shoulder Dystocia: Maternal
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
Prevention in 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
  3. Early induction does not reduce dystocia cases
    1. Kjos (1993) Am J Obstet Gynecol 169:611
Management
1. See Shoulder Dystocia Management
References

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This page was written by Scott Moses, MD. This page was last revised before 5/10/08, prior to consistent tracking of revision date. This page was last published on 6/1/2008. Please send comments and questions to the editor. Contact information may be found on the page About the Family Practice Notebook. These pages are best viewed with Microsoft Internet Explorer 6.0.