Oligohydramnios

Oligohydramnios refers to an amniotic fluid volume that is less than expected for gestational age. Oligohydramnios increases the risk of perinatal morbidity and mortality at all stages of pregnancy. The extent of the risk depends on the underlying cause, severity, and gestational age at diagnosis and delivery. While oligohydramnios is often idiopathic, known causes include preterm premature rupture of membranes, fetal structural abnormalities, placental abruption, fetal chromosomal abnormalities and genetic syndromes, maternal medication use, uteroplacental insufficiency, and twin-to-twin transfusion syndrome. Complications include restricted fetal movements leading to musculoskeletal abnormalities (contractures) and facial deformities (Potter Sequence). In severe cases, oligohydramnios may also result in pulmonary hypoplasia, umbilical cord compression, and fetal/neonatal death. Oligohydramnios is a sonographic diagnosis. Management depends on the underlying cause. Treatment options are limited and depend on the etiology. In select cases (such as twin-to-twin transfusion syndrome or genitourinary outlet obstruction), in utero surgery may be curative. Amnioinfusion can be used in labor to resolve fetal heart rate abnormalities due to umbilical cord compression and decrease the risk of cesarean delivery. This review contains 4 figures, 2 tables, and 63 references. Keywords: Oligohydramnios, fetal lung development, ultrasound, perinatal morbidity, preterm premature rupture of membranes, preterm birth