What causes polyhydromnios?

Answer 1

n most cases, the exact cause cannot be identified. A single case of polyhydramnios may have one or more causes. Some cases are due to maternal diabetes mellitus, which causes fetal hyperglycemiaand resulting polyuria(fetal urine is a major source of amniotic fluid) and also rh-isoimmunisation can cause it. Few cases are associated with fetal anomalies that impair the ability of the fetus to swallow (the fetus normally swallows the amniotic fluid). These anomalies include:

• gastrointestinalabnormalities such as esophageal atresia, duodenal atresia, facial cleft, neck masses, tracheoesophageal fistula, and diaphragmatic hernias. An annular pancreas causing obstruction may also be the cause.
• Bochdalek's hernia, in which the pleuro-peritoneal membranes (especially the left) will fail to develop & seal the pericardio- peritoneal canals. This results in the stomach protrusion up into the thoracic cavity, and the fetus is unable to swallow sufficient amounts of amniotic fluid.
• fetal renaldisorders that results in increased urine production during pregnancy, such as in antenatal Bartter syndrome.[6]Molecular diagnosis is available for these conditions.[7]
• neurological abnormalities such as anencephaly, which impair the swallowing reflex
• chromosomal abnormalities such as Down's syndrome and Edwards syndrome (which is itself often associated with GI abnormalities)
• Skeletal dysplasia, or dwarfism. There is a possibility of the chest cavity not being large enough to house all of the baby's organs causing the trachea and esophagus to be restricted, not allowing the baby to swallow the appropriate amount of amniotic fluid.

It can also be caused by intrauterine infection (TORCH)

In a multiple gestation pregnancy, the cause of polyhydramnios usually is twin-twin transfusion syndrome.

Other maternal causes include cardiac or kidneyproblems. Additionally, chorioangioma of the placenta can also cause this condition.

A recent study distinguishes between mild and severe polyhydramnios and showed that Apgar score of less than 7, perinatal death and structural malformations only occurred in women with severe polyhydramnios.[8]In another study, all patients with polyhydramnios, that had a sonographically normal fetus, showed no chromosomal anomalies