Oligohydramnios is a condition in pregnancy characterized by a deficiency in amniotic fluid. Diagnosis is made by an AFI (amniotic fluid index) ≤ 5 on U/S. It is typically caused by fetal urinary tract abnormalities such as b/l renal agenesis, fetal polycystic kidneys, GU obstruction; as well as ROM and chronic uteroplacental insufficiency. In diagnosing Oligo, one must r/o ROM (rupture of membrane…a leak) using the nitrazine paper test (vaginal pH is typically acidic, when the sac ruptures it becomes alkaline (>7.0). It can be treated in some cases via amnioinfusion during labor to prevent cord compression. Complications include cord compression --> fetal hypoxia, musculoskeletal abnormalities such as facial distortion and clubfoot, pulmonary hypoplasia, and IUGF.
The use of oligohydramnios as a predictor of gestational complications is controversial.