Summary of Oligohydramnios
Oligohydramnios is the presence of too little amniotic fluid in the amniotic sac. Causes include placental insufficiency, and any fetal condition that decreases fetal urination like posterior urethral valves or bilateral renal agenesis. It is diagnosed on ultrasound by measuring the deepest fluid pocket in all four quadrants of the amnion and calculating the amniotic fluid index. A value of less than five centimeters is diagnostic. The condition may trigger the Potter sequence (aka Potter syndrome) and cause in utero renal failure and pulmonary hypoplasia.