Polyhydramnios

Polyhydramnios refers to an excess of amniotic fluid, i.e., more than expected for the gestational age, which causes uterine distention. The etiology is unknown in approximately 70% of cases, but it may be caused by maternal conditions (e.g., diabetes, rhesus incompatibility) or fetal abnormalities (e.g., chromosomal or structural). Diagnostics include physical examination, ultrasound, and blood tests. Management involves antepartum fetal surveillance, amnioreduction if there are severe symptoms , and treatment of the underlying cause. Complications include fetal malposition, umbilical cord prolapse, premature birth, and premature uterine contractions.

• Typically idiopathic (∼ 70% of cases) ^[1]
• Fetal anomalies
  • Gastrointestinal (e.g., esophageal atresia, duodenal atresia and stenosis): reduced swallowing and absorption of amniotic fluid
  • CNS: anencephaly; (leads to impaired swallowing of amniotic fluid, leakage of cerebrospinal fluid, and increased urination due to lack of fetal ADH), meningomyelocele (due to leakage of cerebrospinal fluid) ^[2]
  • Pulmonary: cystic lung malformations
  • Multiple pregnancy: twin-to-twin transfusion syndrome
  • Fetal anemia ^[3]
  • Chromosomal aberrations
  • Intrauterine infections (e.g., congenital TORCH infections)
• Maternal conditions
  • Diabetes mellitus
  • Rh incompatibility (e.g., hemolytic disease of the newborn)

• Physical examination: abdominal girth and uterine size large for gestational age
• Ultrasound
  • AFI ≥ 25 cm
  • Assess for fetal anomalies
• Others
  • Rh screen
  • Screening for gestational diabetes

• All patients should obtain a regular biophysical profile with a nonstress test.
• Amnioreduction: drainage of excess amniotic fluid
  • Indications: severe abdominal discomfort, uterine irritability, severe shortness of breath
  • Complications: preterm labor, premature rupture of membranes
• Treatment of underlying cause (e.g., glycemic control in diabetic mothers, intrauterine exchange transfusion in hemolytic disease of the newborn)

• Fetal malposition
• Umbilical cord prolapse
• Premature birth
• Premature rupture of membranes
• Premature uterine contractions

We list the most important complications. The selection is not exhaustive.