Oligohydramnios

Question 1

What is oligohydramnios?

Answer 1

Amount of amniotic fluid < 500 mL in the third trimester

Question 2

What are some causes of oligohydramnios?

Answer 2

(Fetal anomalies) Urethral obstruction (e.g., posterior urethral valves)
Bilateral renal agenesis
Autosomal recessive polycystic kidney disease (ARPKD)
(Maternal conditions) Late or post-term pregnancies (> 42 weeks of gestation)
Placental insufficiency
Preeclampsia
Premature rupture of membranes

Question 3

What are the complications of oligohydramnios?

Answer 3

Intrauterine growth restriction (diminished mobility of the fetus)
Intrauterine compression and decreased amniotic fluid ingestion → Potter sequence: pulmonary hypoplasia (cause of death due to severe neonatal respiratory insufficiency), craniofacial abnormalities, limb anomalies

Question 4

How is oligohydramnios diagnosed?

Answer 4

Abdominal girth and uterine size small for gestational age
(Ultrasound) Amniotic fluid index (AFI): semiquantitative tool to assess amniotic fluid volume (normal: > 5–24 cm)
Oligohydramnios: ≤ 5 cm

Question 5

What is the treatment of oligohydramnios?

Answer 5

Amnioinfusion: infusion of fluid into the amniotic cavity through amniocentesis
Treat underlying cause (i.e. preeclampsia, premature rupture of membranes, placental insufficiency)
Delivery if the fetus close to term