Polyhydramnios - Too Much Amniotic Fluid

Polyhydramnios usually means that there is an increased amount of amniotic fluid present. The amount of amniotic fluid is usually determined by fetal urination and fetal swallowing, so anything that impairs either of these can impact the amniotic fluid.

The amniotic fluid increases until about 34 weeks and then slightly decreases toward the due date.

The most reliable method of determining the amnount of amniotic fluid is the Amniotic Fluid Index and many doctors will do this test first in order to make the right diagnosis. At 32 weeks, for example, the normal AFI is between 86 mm and 242 mm.

• In over 60% of cases of polyhydramnios, the cause is not found (idiopathic).
• 20% of the time there is a fetal problem (for example, neural tube defect, abdominal wall defect, obstruction of the GI tract, cardiac problems, placental chorioangioma)
• 20% of the time there is a maternal problem (for example, diabetes, Rh disease)

When polyhydramnios is found, your doctor usually does some additional tests to see if a cause can be found.