Oligohydramnios treatment at Midwest Fetal Care Center

What is oligohydramnios?

Oligohydramnios (oh-lee-go-hi-DRAM-nee-ohs) occurs during pregnancy when the amount of amniotic fluid, the protective liquid that surrounds the unborn baby in the uterus, is lower than normal. The condition occurs in 1 percent to 2 percent of all pregnancies. Oligohydramnios can be an isolated condition (meaning no other medical condition or birth defect occurs with it), but it is also associated with certain birth defects and genetic conditions.

Oligohydramnios increases the risk of miscarriage or stillbirth. It can also cause the baby to be born with severe abnormalities, including underdeveloped lungs. This is because amniotic fluid plays an essential role in lung development. The unborn baby “breathes” the fluid into the lungs, where it pushes open the air sacs and stimulates them to grow. During the middle of the second trimester (16 to 24 weeks), the baby undergoes an important phase of lung development. If the amniotic fluid is very low during this period, the baby may not create enough lung tissue and may have trouble breathing at delivery.

Amniotic fluid also provides room for the baby to move, wiggle, and kick during development.  If the fluid is very low for a long time, the baby may develop tightness in the joints, called contractures, due to an inability to stretch out and move.

Another function of amniotic fluid is to cushion the baby’s umbilical cord. Low levels of amniotic fluid, therefore, raise the risk of umbilical cord compression, which obstructs the flow of blood — and oxygen and nutrients — to the baby.

Expert care team

At Midwest Fetal Care Center, a collaboration between Children’s Minnesota and Allina Health, we specialize in individual attention that starts with you having your own personal care coordinator to help you navigate your baby’s treatment process. We use a comprehensive team approach to oligohydramnios and any associated anomalies. That way, you are assured of getting the best possible information by some of the most experienced physicians in the country. For oligohydramnios, your care team will start with a maternal-fetal specialist, but may also include a pediatric kidney specialist, a neonatologist, a pediatric surgeon, a geneticist, a nurse specialist care coordinator, a fetal care clinical social worker and several other technical specialists. This entire team will follow you and your baby closely through the evaluation process, and will be responsible for designing and carrying out your complete care plan.

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What could cause oligohydramnios?

Several factors can lead to lower-than-normal amounts of amniotic fluid. One is a premature rupture of the membranes, or amniotic sac. If there is a small hole in the amniotic sac (bag of waters), amniotic fluid can leak into the mother’s vagina, leaving lower-than-normal amounts around the baby. While we often think of the bag of waters breaking all at once, a small leak can cause a slow trickle of water over time instead of a dramatic gush.

After the 20th week of pregnancy, amniotic fluid consists mostly of the baby’s urine. Anything that causes the baby to produce less urine than usual can therefore result in low amounts of amniotic fluid. Those factors include the following:

  • Problems with the baby’s kidneys. A kidney-related birth defect — kidneys that are absent or non-working, for example — will severely restrict the production of urine and amniotic fluid.
  • Problems with the baby’s bladder or urethra. If the baby has a blockage of the urethra or bladder, then the urine formed may become trapped in the bladder and not released into the amniotic sac, resulting in low levels of amniotic fluid.
  • Poor functioning of the baby’s placenta. The baby receives water, nutrients, and oxygen from the placenta through the umbilical cord. If the placenta is not able to produce enough water and nutrients for the baby, then the baby may produce less urine. This condition is most common in babies with intrauterine growth restriction.

In some cases involving twins, oligohydramnios is caused by twin-to-twin transfusion (TTT) syndrome, a serious placenta-related condition that results in one twin surrounded by too little amniotic fluid and the other surrounded by too much.

How is oligohydramnios diagnosed?

Oligohydramnios is diagnosed by ultrasound. In some cases — if the baby has a birth defect involving the kidneys or bladder, for example — oligohydramnios may be seen on the 20-week ultrasound, or even earlier.  In other cases, such as ones involving rupture of the membranes or poor functioning of the placenta, the fluid levels may be normal early in pregnancy and become low later on.

In all these cases, the diagnosis of oligohydramnios is confirmed by using the ultrasound image to visually measure a pocket of amniotic fluid in each of the four quadrants of the uterus and then adding up these measurements.

To determine if your baby’s amniotic sac is leaking fluid, your doctor will perform a pelvic examination to look for signs of pooled amniotic fluid in the vagina. A swab of that fluid may also be tested for chemicals found only in amniotic fluid. If these tests are positive, then your baby’s bag of waters has likely broken.

Prenatal screening and care

The prenatal management of babies with oligohydramnios starts with acquiring as much information about the condition as early as possible. To gather that information, we may recommend one or more prenatal screening techniques, including high-resolution fetal ultrasonography, fetal echocardiography, and Doppler ultrasound.

Types of screening

What is high-resolution fetal ultrasonography?

High-resolution fetal ultrasonography is a non-invasive test performed by one of our ultrasound specialists. The test uses reflected sound waves to create images of the baby within the womb. We will use ultrasonography to follow the development of your baby’s kidneys and other internal organs and the volume of amniotic fluid that surrounds your baby throughout the pregnancy.

What is fetal echocardiogram?

Fetal echocardiography (“echo” for short) is performed at our center by a pediatric cardiologist (a physician who specializes in fetal heart abnormalities). This non- invasive, high-resolution ultrasound procedure looks specifically at how the baby’s heart is structured and functioning while in the womb. This test is important because babies with birth defects are at increased risk of heart abnormalities.

What is Doppler ultrasound?

Doppler ultrasound uses sound waves to measure the speed of blood flow through your baby’s umbilical cord or blood vessels. Measuring the blood flow enables us to assess how well your baby’s placenta is working — specifically, how well blood is flowing between the placenta and your baby. Problems with blood flow are most common among babies with intrauterine growth restriction.

What happens after my evaluation is completed?

After we have gathered all the anatomic and diagnostic information about your baby,  our team will meet with you to discuss the results. Because oligohydramnios is associated with an increased risk of complications during pregnancy and birth, we will recommend that your pregnancy be followed closely, including with extra ultrasound screenings.

Managing oligohydramnios after delivery and birth

Your child’s medical team will design a management plan tailored to your child’s specific needs. The specifics of the plan will depend on why we think your baby’s amniotic fluid is low.

  • If the amniotic fluid is low because your membranes have ruptured, you will be admitted to the hospital so we can monitor you for signs of preterm labor. You will also receive antibiotics to prevent infection, and may have your labor induced, depending on how far along you are in the pregnancy.
  • If the amniotic fluid is low because the baby’s placenta is not functioning well, you will be scheduled for frequent testing, possibly including Doppler ultrasound. We will closely monitor how your baby is doing and how the placenta is functioning. Sometimes, mothers need to be admitted to the hospital for this monitoring. In addition, you may be given medications to prepare your baby’s lungs for the possibility of an early delivery. In some cases, babies with poorly functioning placentas need to be delivered early to prevent fetal distress or stillbirth.
  • If your baby’s amniotic fluid is low because of an anatomic problem with the baby’s kidneys, bladder, or urethra, the management plan for your baby will be based on the specific birth defect. We will try to identify any complicating factors that might require additional therapies or consultations. That way we can be prepared during and after delivery to optimally care for your infant. We will also help arrange consultations for you with pediatric urologists or nephrologists (kidney specialists), who will advise you on any surgery or other specialized care your baby may need after birth. In some cases, such as those involving lower urinary tract obstructions (LUTO), we may offer a prenatal intervention as well.
  • If there is concern that your baby may have inadequate lung development due to prolonged oligohydramnios early in pregnancy, we will work with your family, your child’s neonatologist, and palliative care specialists to carry out the kind of treatment and care you want for your baby during and after birth.

Treatment for oligohydraminos after birth

Babies with oligohydramnios can be delivered vaginally. They are, however, at increased risk during delivery of being in an abnormal position (not “presenting” head first) and of having temporary drops (decelerations) in their heart rate. Either of those situations may require a Cesarean section. During labor, your baby will be monitored closely, and your doctor will be prepared for all complications or outcomes.

If there are any concerns of associated birth defects, your baby may be born at The Mother Baby Center at Abbott Northwestern and Children’s Minnesota in Minneapolis or at The Mother Baby Center at United and Children’s Minnesota in St. Paul. Children’s Minnesota is one of only a few centers nationwide with a birth center located within the hospital complex. This means that your baby will be born just a few feet down the hall from our newborn intensive care unit (NICU). Also, many of the physicians you have already met will be present during or immediately after your baby’s birth to help care for your baby right away.

What is my baby’s long-term prognosis?

The prognosis for babies with oligohydramnios is related to the underlying reason for the condition, as well as to how low the level of amniotic fluid drops and when in pregnancy the levels became low. Babies who develop oligohydramnios after 23 to 24 weeks usually have adequate lung development and an excellent prognosis, depending on when in pregnancy they are delivered.

If the fluid is low because of membrane rupture or poor placental function, the prognosis depends primarily on the baby’s gestational age and weight at delivery. The prognosis is often good, although many of these babies require care in the NICU due to small size or prematurity.

The prognosis for babies whose oligohydramnios is caused by birth defects affecting the kidney or bladder depends on the function of the kidneys after birth. Some babies require dialysis or kidney transplantation in infancy or early childhood, which can be very challenging for families.

If the amniotic fluid levels were very low during the period of the second trimester when lung development peaks, then the baby may not develop enough lung tissue and may have trouble breathing at delivery.  These babies require intensive breathing support and sometimes do not survive due to poor lung development. Babies who develop low amniotic fluid after 23 to 24 weeks, however, usually have adequate lung tissue, even if the fluid levels become very low in later pregnancy.

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