Hydramniosis a condition that occurs when too much amniotic fluid builds up during pregnancy. It is also called amniotic fluid disorder, or polyhydramnios.
Amniotic fluid is a liquid that surrounds and cushions the fetus (unborn baby) inside the uterus. It comes from the baby’s kidneys, and it goes into the uterus from the baby’s urine. The fluid is absorbed when the baby swallows it and through breathing motions.
The amount of fluid increases until the 36th week of pregnancy. After that, it slowly decreases. If the fetus makes too much urine or does not swallow enough, amniotic fluid builds up. This causes hydramnios.
Mild hydramnios may not cause any problems. Often, extra fluid that appears during the second trimester returns to normal on its own. Mild hydramnios is more common than severe hydramnios.
Hydramnios may occur in normal pregnancies with more than one baby (twins, triplets, or more).
Severe hydramnios may mean there is a problem with the fetus. If you have severe hydramnios, your health care provider will look for these problems in your fetus:
Many times, the cause of hydramnios is not found.
Mild hydramnios often has no symptoms. But tell your health care provider if you have:
To check for hydramnios, your health care provider will measure your "fundal height” during your prenatal check-ups. Fundal height is the distance from your pubic bone to the top of your uterus. Your health care provider will also check your baby's growth by feeling your uterus through your belly.
Your health care provider will do an ultrasound if he or she thinks you may have hydramnios. This will measure the amount amniotic fluid around your baby.
Doctors may be able to treat the symptoms of hydramnios, but they cannot usually treat what caused it.
Your health care provider may also do tests to find out why you have extra fluid. These might include:
Hydramnios may cause you to go into labor early.
It is easy for a fetus with a lot of fluid around it to flip and turn. This means there is a greater chance of being in a feet-down position (“breech”) when it is time to deliver. Breech babies can sometimes be moved into a head-down position, but they often have to be delivered by cesarean section.
You cannot prevent hydramnios. If you have symptoms, tell your health care provider so you can be checked and treated, if needed.
Amniotic fluid disorder; Polyhydramnios
Gilbert WM. Amniotic fluid disorders. In: Gabbe SG, Niebyl JR, Simpson JL, et al, eds. Obstetrics: Normal and Problem Pregnancies. 6th ed. Philadelphia, Pa: Saunders Elsevier; 2012:chap 33.
Updated by: Susan Storck, MD, FACOG, Chief, Eastside Department of Obstetrics and Gynecology, Group Health Cooperative of Puget Sound, Bellevue, Washington; Clinical Teaching Faculty, Department of Obstetrics and Gynecology, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M. Health Solutions, Ebix, Inc.
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