Abstract

Oligohydramnios is a condition in pregnancy characterized by a deficiency of amniotic fluid. It is the opposite of polyhydramnios.

Signs and symptoms

The common clinical features are smaller symphysis fundal height, fetal malpresentation, undue prominence of fetal parts and reduced amount of amniotic fluid.

Signs and symptoms | Complications

Complications may include cord compression, musculoskeletal abnormalities such as facial distortion and clubfoot, pulmonary hypoplasia and intrauterine growth restriction. Amnion nodosum is frequently also present (nodules on the fetal surface of the amnion).

The use of oligohydramnios as a predictor of gestational complications is controversial.

Potter syndrome is a condition caused by oligohydramnios. Affected fetuses develop pulmonary hypoplasia, limb deformities, and characteristic facies. Bilateral agenesis of the fetal kidneys is the most common cause due to the lack of fetal urine.

Causes

The cause is not known but is often associated with some:

- fetal chromosomal anomalies

- intra uterine infections

- drugs; PG inhibitors, ACE inhibitors

- renal agenesis or obstruction of the urinary tract of the fetus preventing micturition such as posterior urethral valves in males

- intrauterine growth restriction (IUGR) associated with placental insufficiency

- "amnion nodosum"; failure of secretion by the cells of the amnion covering the placenta

- postmaturity (dysmaturity)

Treatment

A Cochrane review concluded that "simple maternal hydration appears to increase amniotic fluid volume and may be beneficial in the management of oligohydramnios and prevention of oligohydramnios during labour or prior to external cephalic version."

In severe cases oligohydramnios may be treated with amnioinfusion during labor to prevent umbilical cord compression. There is uncertainty about the procedure's safety and efficacy, and it is recommended that it should only be performed in centres specialising in invasive fetal medicine and in the context of a multidisciplinary team.

In case of congenital lower urinary tract obstruction, fetal surgery seems to improve survival, according to a randomized yet small study.