Chapter 218 Polyhydramnios
INTRODUCTION
Description: Polyhydramnios is an abnormal increase in the amount of amniotic fluid surrounding the fetus. This diagnosis is generally reserved for volumes >2 L and amniotic fluid index >24 to 25 cm. (At term, there should be about 800 mL of amniotic fluid present.) This fluid may accumulate gradually over time (chronic hydramnios) or acutely over the course of several days (more common in early pregnancy).
Prevalence: In 0.9% to 1.6% of women, some increase in amniotic fluid is seen during pregnancy (80% mild, 5% severe).
ETIOLOGY AND PATHOGENESIS
Causes: Idiopathic (two thirds), maternal diabetes, multiple gestation, fetal anomalies (50% of patients with severe hydramnios: central nervous system, gastrointestinal tract, chromosomal).
