Shoulder Dystocia

Published on 06/06/2015 by admin

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Last modified 06/06/2015

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Chapter 222 Shoulder Dystocia

INTRODUCTION

Description: Shoulder dystocia is an obstruction to delivery caused by impaction of the fetal shoulder behind the maternal symphysis. Less commonly it can be due to impaction of the posterior fetal shoulder on the sacral promontory. Shoulder dystocia is most often an unpredictable and unpreventable obstetric emergency, usually defined as a delivery that requires additional obstetric maneuvers (following failure of gentle downward traction on the fetal head) to effect delivery of the shoulders.

Prevalence: 0.15% of fetuses weighing ≥2500 g (5 pounds 8 oz), 1% to 5% for ≥4000 g (8 pounds 13 oz), 19% ≥4500 g (9 pounds 15 oz); overall 0.6% to 1.4% of vertex deliveries.

Genetics: Tall or large parents are at higher risk.

ETIOLOGY AND PATHOGENESIS

Causes: A relative disproportion between fetus and the birth passage or a misalignment of normally sized structures (fetus and pelvis).

Risk Factors: Fetal macrosomia (risk proportional to weight), pelvic deformity, maternal obesity, diabetes mellitus, post-term pregnancy, prolonged second stage of labor, oxytocin induction, midforceps or vacuum extraction.

CLINICAL CHARACTERISTICS

Signs and Symptoms

• Poor descent during labor

• Retraction of the fetal head onto the perineum following delivery of the chin (“turtle sign”)

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Netters Obstetrics and Gynecology