Oligohydramnios: Definition - Presbyterian/St. Luke's Medical Center

Oligohydramnios is too little fluid in the amniotic sac. The amniotic sac is the “water bag” inside the womb that cushions and protects your baby. It also allows normal growth and development to occur. Normal amniotic fluid levels vary. The average volume during pregnancy is almost one liter at 36-37 weeks. Less than 10% of pregnant women develop oligohydramnios.

Low amniotic fluid can indicate a problem in the mother or the baby. It can also cause problems that vary depending on when in pregnancy oligohydramnios occurs.

Problems in the first half of pregnancy:

Higher risk of miscarriage
Compression of the baby, leading to birth defects
Lack of lung development
Increased risk of infection

Problems in the second half of pregnancy:

Reduced growth of baby
Induction of labor and delivery before 39 weeks (called preterm birth)
Fetal distress in labor, possibly leading to cesarean delivery (“C-section”)
Increased risk of infection

Fetus in Utero, Amniotic Fluid

There are many known causes of oligohydramnios. However, sometimes a specific cause cannot be found. Conditions that can cause oligohydramnios include:

Birth defects (eg, neural tube defect)
A problem with the placenta (the tissue that supplies the baby with nutrients through the umbilical cord)
Tear in the amniotic sac (also called rupture of membranes)
Pregnancy continuing past the due date
Problems in the mother, such as dehydration, diabetes, or high blood pressure
Complication of medicines such as:
- ACE inhibitor to manage blood pressure
- Tocolytic medicine to reduce uterine contractions

Risk Factors

Risk factors that increase your chance of getting oligohydramnios include:

Increased maternal age
Smoking

Symptoms

Oligohydramnios usually does not cause women to have any symptoms. If the amniotic sac has a tear, you may notice a gush of fluid from the vagina. The fluid may leak out slowly causing constant wetness. Your doctor may also notice that your abdomen is smaller than expected for your gestational age.

Diagnosis

Your doctor will ask about your symptoms and medical history. A physical exam will be done. If you are not under the care of an obstetrician, you may be referred to one.

Your doctor may need your body fluids tested. This can be done with:

Blood glucose
Amniocentesis
Amniotic fluid index

Your doctor may also need pictures of your uterus and fetus. This can be done with ultrasound.

Treatment

Your doctor will monitor you and your baby closely to make sure the condition does not get worse and that the fetus remains healthy. You will probably have more frequent prenatal visits and regular ultrasound tests. It is very important to keep these appointments.

Treatment options include:

Increased fluid intake. Some studies have found that having women drink two liters of water can increase the amount of amniotic fluid.
Your doctor may add fluid to the amniotic sac after you are in labor. This will help cushion the umbilical cord during contractions.
If you are diagnosed with oligohydramnios, it is important to take good care of yourself. Drink plenty of fluids, rest often, stop smoking, and eat a healthy diet. If you see any signs of early labor (such as contractions or vaginal bleeding), contact your doctor right away.

Prevention

The only way to prevent oligohydramnios is to treat its causes if possible. Getting regular check-ups while you’re pregnant can help find the problem early. If you are taking medications for blood pressure, see your doctor before getting pregnant. If you smoke, quit.

Oligohydramnios