Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at September 1, 2016

About 1 percent of pregnancies have occurrences of Polyhydramnios. Some cases do not pose much risk to either woman or child while others can cause complications that may lead to greater problems in gestation and delivery. This condition can indicate a greater risk of premature birth.


Definition & Facts

Polyhydramnios is the medical condition of having excessive amounts of amniotic fluid in the amniotic sac during pregnancy. This condition happens to about 1 percent of pregnancies. It occurs when the amniotic fluid index (AFI) is greater than 24 cm.

Amniotic fluid is what surrounds the baby in the amniotic sac and is essential for healthy development of the fetus. It also cushions the fetus from external impact and protects the baby from extreme temperature changes and infections. The amniotic fluid also plays a role in processing the waste of the baby.

The level of amniotic fluid usually increases as pregnancy progresses. In some cases, polyhydramnios may just go away on its own and not present any symptoms. There are other times when that is not the case. 

Symptoms & Complaints

Symptoms usually result from pressure being exerted on the uterus or nearby organs. Severe polyhydramnios could cause shortness of breath or difficulty breathing. The swelling of legs and calves (edema), vulva, and abdominal wall, and the decrease in urination are other symptoms of this condition.

Doctors may suspect this condition as well if the uterus is enlarged or if they have trouble hearing the heartbeat of the fetus. In most women with polyhydramnios, the buildup of fluid is slow at first. The excess buildup of fluid becomes noticeable after 30 weeks of pregnancy. This gradual accumulation of fluid is called chronic polyhydramnios.

There are rare cases, however when the fluid can already start building up as soon as the 18th month of pregnancy. This is called acute polyhudramnios. Fetuses with this condition are at risk of problems like umbilical cord prolapse or placental abruption, premature birth, or prenatal death. Abnormalities or anomalies should be checked at delivery (newborn screening).


Polyhydramnios is often associated with the mother carrying twins. This is caused by what is called twin-to-twin transfusion syndrome where one twin has too little amniotic fluid while the other has too much. Certain infections can also cause this condition such as rubella, toxoplasmosis, and syphilis. At times it is associated with the mother having diabetes mellitus, in which the baby is usually larger than it should be at its stage of development.

Intestinal atresia is a condition in the fetus where a blockage in the baby’s gut prevents them from absorbing the usual amount of fluid. This usually is followed by a surgical procedure after birth. Sometimes, this condition happens when the mother has rhesus disease (Rh disease), where the mother’s antibodies cross the placenta. This may cause anemia in the fetus. Fetal anemia occurs when there is a lack of red blood cells in the fetus.

Another cause of this condition could be placental chorioangioma or a growth of blood vessels in the placenta. A fluid buildup or genetic problem with the fetus may sometimes cause polyhydramnios. Other causes may be chromosomal. Chromosomal abnormalities such as Down syndrome or Edwards syndrome may be causes of polyhydramnios.

Diagnosis & Tests

If an abnormally fast buildup of fluid is suspected by the mother, an fetal ultrasound scan may be suggested by the obstetrician so that the depth of fluid around the fetus can be measured. Most women suspected of polyhydramnios will need an medical ultrasound to ascertain the extent of the fluid buildup. The doctor will most likely perform a physical examination and attempt to establish what the patient's symptoms are. The doctor will check for the following:

Most polyhydramnios occurs among women with gestational diabetes and are usually tested before diagnosis. This is often accompanied by a glucose tolerance test to check if the buildup is caused by gestational diabetes. This usually does not require hospital admission unless the buildup is severe.

If the scan shows that there are problems with fetus, the doctor might suggest performing an amniocentesis. This is where a sample of the amniotic fluid is taken using a needle. This is to test for chromosomal abnormalities or genetic mutations in the fetus.

Karyotype is also a test which is used to screen the baby’s chromosomes for abnormalities. The samples needed can be taken from amniocentesis or from a chorionic villus sampling where a piece of placenta is taken. Polyhadramnios is also associated with some caesarean section deliveries and heavy bleeding due to lack of uterine muscle tone (uterine atony) after the delivery.

Treatment & Therapy

Mild polyhydramnios without any symptoms may be managed through watchful waiting. Constant monitoring of the fetus heart with a fetal echocardiogram and Doppler ultrasound may be needed.

Polyhydramnios that is accompanied by symptoms may require hospital admission. Amnioreduction may also be performed in which amniotic fluid is drained to relieve pressure within the amniotic sac. This procedure does carry a small risk of complications including preterm labor, placental abruption and bleeding.

Oral medication called indometacin helps reduce fetal urine and the volume of amniotic fluid. Indometacin is not recommended for anyone beyond 31 weeks of pregnancy as that it may pose the fetus to be at risk of heart problems. Indometacin is a nonsteroidal anti-inflammatory drug.

Sometimes, antacids may be prescribed to relieve nausea and heartburn. The doctor will also advise a period of bed rest.

Prevention & Prophylaxis

Polyhaydramnios cannot be prevented. In more than half of the cases reported, the cause is simply unknown. If the cause is a genetic factor, then it is at present, unavoidable. If the condition is caused by maternal diabetes, treating the diabetes may assist in preventing the condition from worsening and causing complications to the pregnancy and delivery.