Specialty obstetrics ICD-9-CM 657 MedlinePlus 003267 | ICD-10 O40 DiseasesDB 10319 eMedicine radio/566 | |
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Polyhydramnios (polyhydramnion, hydramnios, polyhydramnios) is a medical condition describing an excess of amniotic fluid in the amniotic sac. It is seen in about 1% of pregnancies. It is typically diagnosed when the amniotic fluid index (AFI) is greater than 24 cm. There are two clinical varieties of polyhydramnios:
Contents
The opposite to polyhydramnios is oligohydramnios, a deficiency in amniotic fluid.
Causes
In most cases, the exact cause cannot be identified. A single case may have one or more causes, including intrauterine infection (TORCH), rh-isoimmunisation, or chorioangioma of the placenta. In a multiple gestation pregnancy, the cause of polyhydramnios usually is twin-to-twin transfusion syndrome. Maternal causes include cardiac problems, kidney problems, and maternal diabetes mellitus, which causes fetal hyperglycemia and resulting polyuria (fetal urine is a major source of amniotic fluid).
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. In another study, all patients with polyhydramnios, that had a sonographically normal fetus, showed no chromosomal anomalies.
(M/C for polyhydramnio is fetal anomalies 'Williams Obstetrics, 24th Edition - Cunningham, Leveno, Bloom et al. Table 11-2) but these anomalies include:
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.