Polyhydramnios

Polyhydramnios (polyhydramnion, hydramnios, polyhydramnios) is a medical condition describing an excess of amniotic fluid in the amniotic sac. It is seen in 0.2 to 1.6% of pregnancies, ,. It is typically diagnosed when the amniotic fluid index (AFI) is greater than 20 cm ( ≥ 20 cm),

The opposite to polyhydramnios is oligohydramnios, a deficiency in amniotic fluid.

Causes
A single case of polyhydramnios may have one or more causes. About 14% of cases are due to maternal diabetes mellitus, which causes fetal hyperglycemia and resulting polyuria (fetal urine is a major source of amniotic fluid)and also rh-isoimmunisation can cause it. About another 20% of 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:


 * gastrointestinal abnormalities such as esophageal atresia, duodenal atresia, facial cleft, neck masses, and tracheoesophageal fistula
 * fetal renal disorders that results in increased urine production during pregnancy, such as in antenatal Bartter syndrome. Molecular diagnosis is available for these conditions.
 * chromosomal abnormalities such as Down's syndrome and Edwards syndrome (which is itself often associated with GI abnormalities)
 * neurological abnormalities such as anencephaly, which impair the swallowing reflex

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

It can also be caused by some systemic medical conditions in the mother, including cardiac or kidney problems. it can also be caused by intrauterine infection(TORCH)

Additionally, chorioangioma of the placenta can also cause this condition.

However, it should be reported that in 60-65% of cases it is unknown why polyhydramnios happens.

Diagnosis
There are several pathologic conditions that can predispose a pregnancy to polyhydramnios. These include a maternal history of diabetes mellitus, Rh incompatibility between the fetus and mother, intrauterine infection, and multiple pregnancies.

During the pregnancy, certain clinical signs may suggest polyhydramnios. In the mother, the physician may observe increased abdominal size out of proportion for her weight gain and gestation age, uterine size that outpaces gestational age, shiny skin with stria (seen mostly in severe polyhydramnios), dyspnea, and chest heaviness. When examining the fetus, faint fetal heart sounds are also an important clinical sign of this condition.

Associated conditions
Fetuses with polyhydramnios are at risk for a number of other problems including cord prolapse, placental abruption, premature birth and perinatal death. At delivery the baby should be checked for congenital abnormalities. Another cause of polyhydramnios is skeletal dysplasia, or dwarfism, in the baby. 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.

Treatment

 * Mild asymptomatic polyhydraminos is managed expectantly. For a woman with symptomatic polyhydrminos may need hospital admisssion. Antacids may be prescribed to relive heartburn and nausea.
 * Dietary salt restriction is recommended.
 * In some cases, amnioreduction, also known as therapeutic Amniocentesis, has been used in response to polyhydramnios.