polyhydramnios

Polyhydramnios refers to a situation where the amniotic fluid volume is more than expected for gestational age.

It is generally defined as:

Epidemiology

It can occur in approximately 1-1.5% of pregnancies.

Clinical presentation

The patient may clinically present as a large for dates uterus.

Pathology

Polyhydramnios occurs as a result of either increased production or decreased removal of amniotic fluid. The etiology of polyhydramnios can be due to a vast variety of maternal and fetal disorders.

It is usually detected after 20 weeks (often 3 trimester).

Causes

The potential causes of polyhydramnios are variable including:

Associations

Polyhydramnios is associated with the poor outcome if present in combination with intrauterine growth restriction (IUGR); usually seen in aneuploidies 18,13, and 21.

Classification

This classification is general consensus based on common practices at the time of writing (July 2016) but this varies according to countries and gynecologist association guidelines.

Some classify the severity of polyhydramnios as

  • mild: single deepest pocket at 8-11 cm or AFI 25-30
  • moderate: single deepest pocket at 12-15 cm or AFI 30.1-35
  • severe: single deepest pocket >16 cm or AFI >35

Complications

The risk of the following obstetric complications is increased when polyhydramnios is present due to over-expansion of the uterus:

  • maternal dyspnea
  • premature membrane rupture
  • preterm labor
  • abnormal fetal presentation
  • umbilical cord prolapse
  • postpartum hemorrhage: due to reduced uterine myometrial tone

Treatment and prognosis

The prognosis is variable dependent on associated conditions. Usually minimal or no interventional required for idiopathic mild uncomplicated cases. Options include:

  • improved maternal diabetes control
  • cesarian section if there is profound macrosomia
  • therapeutic amniocentesis/amnioreduction
  • Indomethacin

See also