Polyhydramnios: Excessive Amniotic Fluid

She was breathless when she shuffled her way slowly into the consultation room. Her feet were swollen from ankles up to the legs. After climbing up the examination couch with some difficulty and pointing at her huge tummy, she asked, “Doc, can I deliver my baby soon?”

N,32 and a first-time mum was at her 36 weeks of gestation. There was no history suggesting viral infection during her antenatal period. She was not a carrier of thalassemia and her blood group was O Rh+ve. Glucose tolerance test was normal and blood tests for rubella( German Measle), syphilis and toxoplasma were negative

Non-invasive prenatal test (NIPT) was normal. Ultrasound scan for foetal anomalies at 22 weeks gestation did not reveal any obvious structural defects. Foetal weight was average and the amniotic fluid index (AFI) was normal. However, during the growth scan at 32 weeks of gestation, the amniotic fluid was noted to be excessive with an AFI of 28.

N was suffering from a condition called polyhydramnios.

What is polyhydramnios?

Amniotic fluid is a clear liquid that surrounds the foetus inside the womb. It promotes foetal growth, helps develop its lungs, keeps a constant temperature around the baby and acts as a protective cushion for the baby.

The amount of amniotic fluid is greatest at about 34 weeks of gestation when it averages 800ml. At 40 weeks of gestation, the level drops down to about 600ml.

Polyhydramnios occurs when the volume of amniotic fluid exceeds normal levels. It is present in about 1 to 2 percent of pregnancies. Most cases are usually mild and result from a gradual buildup of amniotic fluid during the second half of pregnancy. But in severe cases, major complications to the mother and baby can appear.

What are the causes of polyhydramnios?

In 50-60% of severe cases, the cause is unclear. Some of the known causes include:

· A birth defect that affects the baby's digestive or central nervous system

· Maternal diabetes before or during pregnancy

· Big baby

· Twin pregnancy

· Foetal anaemia: A lack of red blood cells in the baby

· Blood incompatibilities between mother and baby

· Infection during pregnancy