Oligohydramnios

A decreased amniotic fluid volume for gestational age, usually diagnosed sonographically as an amniotic fluid index ≤ 5 cm or a single deepest vertical pocket <2 cm, and associated with increased perinatal morbidity and mortality. Posible causes are premature Rupture of Membranes, congenital anomalies reducing fetal urine output (urinary tract or kidneys), chromosomal abnormalities (trisomy 18 or 13), intrauterine growth restriction, post-term pregnancy beyond 42 weeks, fetal demise, placental insufficiency, twin-to-twin transfusion syndrome, placental abruption, preeclampsia, maternal diabetes, maternal dehydration, and medications (ACE-inhibitors, NSAIDs).