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Problems With Amniotic Fluid

(Polyhydramnios; Hydramnios; Oligohydramnios)

By

Antonette T. Dulay

, MD, Main Line Health System

Last full review/revision Aug 2019| Content last modified Aug 2019
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Amniotic fluid is the fluid that surrounds the fetus in the uterus. The fluid and fetus are contained in membranes called the amniotic sac. Problems with amniotic fluid include too much or too little amniotic fluid and infection of the fluid, amniotic sac, and/or placenta (called an intra-amniotic infection).

Pregnancy complications, such as too much or too little amniotic fluid, are problems that occur only during pregnancy. They may affect the woman, the fetus, or both and may occur at different times during the pregnancy. However, most pregnancy complications can be effectively treated.

Too much amniotic fluid

Too much amniotic fluid (polyhydramnios or hydramnios) stretches the uterus and puts pressure on the diaphragm of pregnant women.

Too much fluid may accumulate because of the following:

However, about half the time, the cause is unknown.

Too much amniotic fluid can lead to several problems:

Too little amniotic fluid

There tends to be too little amniotic fluid in the following situations:

In many cases, the cause is unknown.

Taking certain drugs such as angiotensin-converting enzyme (ACE) inhibitors (including enalapril or captopril) during the 2nd and 3rd trimesters can result in too little amniotic fluid. These drugs are usually avoided during pregnancy. However, rarely, they are used to treat severe heart failure. Taking nonsteroidal anti-inflammatory drugs (NSAIDs, such as ibuprofen) late in pregnancy can also reduce the amount of amniotic fluid.

Too little amniotic fluid (oligohydramnios) can also cause problems, such as the following:

  • If the amount of fluid is greatly reduced, the fetus may be compressed, resulting in deformities in the limbs, a flattened nose, a recessed chin, and other problems.

  • The fetus's lungs may not mature normally. (The combination of immature lungs and deformities is called Potter syndrome.)

  • The fetus may not be able to tolerate labor, making cesarean delivery necessary.

  • The fetus may die.

  • The fetus may not grow as much as expected.

Women may notice that the fetus is not moving as much as earlier in the pregnancy.

Diagnosis

  • A doctor's evaluation

  • Ultrasonography

  • Tests to identify the cause

Doctors may suspect too much or too little amniotic fluid when the uterus is too large or too small for the length of the pregnancy.

Sometimes the problem is incidentally detected during ultrasonography. If a problem is detected, doctors can use ultrasonography to determine how much amniotic fluid is present.

If doctors detect too much or too little amniotic fluid, they check for a possible cause. For example, they may examine the vagina and cervix to determine whether the membranes around the fetus have ruptured too soon.

Blood tests may be done to check for disorders that can affect amniotic fluid (such as infections or diabetes). Ultrasonography and other tests (possibly amniocentesis) may be done to check for birth defects in the fetus.

Treatment

  • Ultrasonography to monitor the fetus's growth and to measure amniotic fluid levels

  • Monitoring of the fetus's heart rate

  • Treatment of any underlying disorders

  • Sometimes removal of amniotic fluid

  • Delivery

Ultrasonography is done regularly to monitor how much the fetus is growing and to measure the amniotic fluid levels. The fetus’s heart rate is also regularly monitored when the fetus is lying still and as it moves. This test is done to check on the fetus's well-being (called nonstress testing—see sidebar Monitoring the Fetus).

Any underlying disorders, such as diabetes and high blood pressure, are treated.

When there is too much amniotic fluid, doctors rarely remove the excess fluid. However, the amniotic fluid can be removed with a needle through the woman's abdomen:

  • Labor begins early.

  • Severe problems occur.

When there is too much amniotic fluid, doctors plan to deliver the baby at 39 weeks in certain cases.

When there is too little amniotic fluid, most experts usually recommend delivery between 36 and 37 weeks depending on how the fetus is doing.

NOTE: This is the Consumer Version. DOCTORS: Click here for the Professional Version
Click here for the Professional Version
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