This is defined as an abnormally large volume of Amniotic Fluid. It is sometimes known by the shorter form, hydramnios.

Physiologically, the volume of fluid increases with gestation to a maximum of 800-1000ml at 36-37 weeks. Its purpose is to protect the fetus from trauma and infection. Fetal swallowing causes a reduction in the volume of fluid, and absence of swallowing or a blockage of the fetal gastrointestinal tract may lead to polyhydramnios. Polyhydramnios is therefore strongly linked to fetal abnormality.

The condition is suspected when antenatal examination reveals a uterus that is large for dates.

Fetal parts may be difficult to palpate.

Occasionally the uterus enlarges rapidly. This is known as acute polyhydramnios and is commonest in twin pregnancies. In such cases abnormal connecting blood vessels in the twin placenta result in unequal distribution of blood flow (twin-to-twin transfusion syndrome). The twin receiving the larger amount of blood supply is known as the recipient twin and the twin receiving the smaller amount is known as the donor. The recipient twin produces a large amount of urine and is surrounded by excessive Amniotic Fluid.

Management

The first step is to identify any underlying cause.

Mild polyhydramnios can be simply monitored and treated conservatively.

Pre-term labour is common due to overdistension of the uterus, and measures should be taken to minimise this complication. This includes regular antenatal checks and inspection of the uterus, and bed rest towards the latter stages. (Intramuscular steroids should be given to the mother antenatally if preterm deliver is considered). This helps to improve lung maturity.

Serial ultrasound scans should be carried out to monitor the Amniotic Fluid level and monitor fetal growth.

References

http://www.nlm.nih.gov/medlineplus/e...ages/17123.htm

http://www.emedicine.com/PED/topic1854.htm

http://www.americanpregnancy.org/pre...hydramnios.htm

Books

Attached Images

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