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High-Risk Pregnancy: Hydramnios

High-Risk Pregnancy: Hydramnios


Too much or too little amniotic fluid

Amniotic fluid is an important part of pregnancy and fetal development. This watery fluid is inside a casing called the amniotic membrane (or sac) and fluid surrounds the fetus throughout pregnancy. Normal amounts may vary, but, generally, women carry about 500 ml of amniotic fluid. Amniotic fluid helps protect and cushion the fetus and plays an important role in the development of many of the fetal organs including the lungs, kidneys, and gastrointestinal tract. Fluid is produced by the fetal lungs and kidneys. It is taken up with fetal swallowing and sent across the placenta to the mother's circulation. Amniotic fluid problems occur in about 7 percent of pregnancies.

Hydramnios (too much amniotic fluid) poses a greater threat to the mother, whereas Oligohydramnios (too little of amniotic fluid) poses greater danger to the life of the fetus that she is carrying.

High-Risk Pregnancy: Hydramnios

The Amniotic Fluid Index

How is the level of amniotic fluid measured? Your health care provider uses ultrasound to measure the depth of the amniotic fluid in four different areas of your uterus and adds up the results. This is your amniotic fluid index. If the amniotic fluid depth is less than 5 centimeters (cm), you have oligohydramnios. If the depth measures greater than 25 cm, you have polyhydramnios.


Hydramnios is a condition in which there is too much amniotic fluid around the fetus. It occurs in about 3 to 4 percent of all pregnancies. It is also called polyhydramnios.

Severe hydramnios may signal a problem with the fetus, such as a central nervous system or gastrointestinal defect. In rare cases, it can lead to early labor or even fetal death. Mild hydramnios is more common, and doesn't signal a problem. In fact, extra fluid that appears during the second trimester is likely to return to a normal range without treatment.

What causes hydramnios?

There are several causes of hydramnios. Generally, either too much fluid is being produced or there is a problem with the fluid being taken up, or both. Factors that are associated with hydramnios include the following:

High-Risk Pregnancy: Hydramnios

Maternal factors:

  • Diabetes- If you have diabetes and you're having trouble managing it properly, you can end up with high fluid levels. You'll probably be given a glucose test to see if diabetes is the cause. Such cases are usually mild and relatively easy to resolve by getting the diabetes under control.

Fetal factors:

  • Gastrointestinal abnormalities that block the passage of fluid

  • Abnormal swallowing due to problems with the central nervous system, such as neural tube defects or chromosomal abnormalities

  • Twin-to-twin transfusion syndrome- Polyhydramnios is especially likely in the case of twin-to-twin transfusion syndrome, where the donor twin may suffer from too little amniotic fluid, while the recipient twin is creating too much.

  • Heart failure

  • Congenital infection (acquired in pregnancy)

Too much amniotic fluid can cause the mother's uterus to become over-distended and may lead to preterm labor or premature rupture of membranes (the amniotic sac). Hydramnios is also associated with birth defects in the fetus. When the amniotic sac ruptures, large amounts of fluid leaving the uterus may increase the risk of placental abruption or umbilical cord prolapsewhere it may be compressed.

What are the symptoms of hydramnios?

The following are the most common symptoms of hydramnios. However, each woman may experience symptoms differently. Symptoms may include:

  • Rapid growth of uterus

  • Unusual discomfort in the abdomen - due to the extra pressure

  • Wild fluctuations in your weight;

  • Increased back pain;

  • Extreme swelling in your feet and ankles

  • Uterine contractions

The symptoms of hydramnios may resemble other medical conditions. Always consult your physician for a diagnosis. In women with oligohydramnios, it is particularly important to not smoke, get a very good diet, rest a bit more and observe and report any signs or symptoms of preterm labor.

High-Risk Pregnancy: Hydramnios


In addition to a complete medical history and a physical examination, hydramnios is usually diagnosed with ultrasound by measuring pockets of fluid to estimate the total volume. A score of 25 centimeters (cm) or above is considered high. A normal score for the third trimester is 5 to 25 cm. In some cases, ultrasound is also helpful in finding a cause of hydramnios, such as multiple pregnancy or a birth defect.

Treatment for hydramnios:

Specific treatment for hydramnios will be determined by your physician based on:

  • Your pregnancy, overall health, and medical history

  • Extent of the condition

  • Your tolerance for specific medications, procedures, or therapies

  • Expectations for the course of the condition

  • Your opinion or preference

Treatment for hydramnios may include:

  • Close monitoring the amount of amniotic fluid and frequent follow-up visits with the physician

  • Medication. In certain cases, your doctor may prescribe a prostaglandin inhibitor like Indomethacin, which has been shown to reduce the baby's urine output.

  • Amnioreduction
    - amniocentesis to remove some of the amniotic fluid; this procedure may need to be repeated.

  • Delivery Once labor begins, the large gush of fluid leaving the uterus means you have an increased risk of placental abruption or umbilical cord prolapse. Both of these problems can cut off the baby's oxygen supply and may require an emergency cesarean section.

The goal of treatment is to relieve the mother's discomfort and continue the pregnancy.

High-Risk Pregnancy: Oligohydramnios

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