Polyhydramnios-High Amniotic Fluid Levels
The Vital Role Of Amniotic Fluid
Amniotic fluid is an important part of a baby's life support system in the womb. It serves as protection for the baby, creating a barrier of fluid between the developing baby and the walls of the uterus. It aids in the development of muscles, limbs, lungs and the digestive system of the baby. Soon after the amniotic sac forms, at about 12 days after conception, the amniotic fluid is produced. At first, it is comprised of water provided by the mother. After about 20 weeks gestation, it is primarily made up of fetal urine.
As the baby grows, he or she will "swim" and tumble in the uterus with the aid of the amniotic fluid. In the second trimester, the baby begins to breathe and swallow the amniotic fluid. This fluid increases until about the 32 week of gestation at which point it levels off. While fluid levels may vary, a fluid level between 800 to 1000ml is considered normal. If the measurement of amniotic fluid in the uterus is low, the condition is called olioghydramnios, and if it is high, it is called polyhydramnios.
How The Doctor Knows If There Is Too Much Fluid
A doctor can measure the level of amniotic fluid through several different methods. However, the most common is through the amniotic fluid index (AFI) evaluation, or deep pocket measurements. If the AFI indicates a fluid level of more than 25 centimeters, which is considered above the 95 percentile, or there is a fluid level of 2000ml, or more, then a diagnosis of polyhydramnios is made. Between one and two percent of pregnant women have too much amniotic fluid and most of these cases are considered mild, with only slightly elevated levels of fluid.
What Causes Polyhydramnios?
There is a variety of reasons for increased levels of amniotic fluid. Higher fluid levels indicate an increased chance of congenital defects. If the baby has difficulty swallowing due to a defect, the amniotic fluid levels rise. Intestinal tract blockages or neurological abnormalities are other birth defects which may affect the amniotic fluid levels.
Rh factor was once a common cause for elevated fluid levels, but with increased screening, this has become less of a cause. There has been some correlation found between diabetes and too much amniotic fluid. Another potential cause for fluid build-up is a complication that can affect identical twin pregnancies. The twin-to-twin transfusion syndrome is when one baby gets too much blood and the other too little blood flow due to connections between blood vessels in their shared placenta. According to the Center for Maternal Fetal Medicine, about 65 percent of cases of polyhydramnios result from unknown causes.
Risks And Complications That Arise From Polyhydramnios
The risks associated with polyhydramnios include premature rupture of the membranes (PROM), placental abruption, and growth restriction (IUGR) which results in skeletal malformations. Too much fluid causes about 26 percent of preterm labor and delivery situations. Stillbirth rates are double in pregnancies with polyhydramnios at four in 1000.
Many cases of polyhydramnios are easily treated and do not end in complications. Medication to reduce fluid production before 32 weeks gestation has proven to be 90 percent effective. Amniocentesis can be used to drain fluid, although there are some risks associated with it. Close monitoring of the pregnancy is the best way to determine a course of action should polyhydramnios be a concern.