What is oligohydramnios sequence?
During pregnancy a fetus is bathed in amniotic fluid. Not having enough amniotic fluid is a condition referred to as oligohydramnios. Amniotic fluid is critical. It helps the fetus properly develop. Oligohydramnios is associated with many different conditions affecting a fetus’s organs.
Oligohydramnios sequence is the condition that develops during pregnancy when oligohydramnios occurs. Oligohydramnios sequence, or Potter’s syndrome, is a chain of events that result in severe abnormalities of the fetus. The name refers to Dr. Edith Potter, who first characterized the physical appearance of the fetuses or newborns that have the condition.
Not all fetuses develop abnormalities because of low levels of amniotic fluid. The occurrence of Oligohydramnios sequence depends a few factors: the stage of pregnancy and level of amniotic fluid. The later stages of pregnancy appear to be the most troublesome. If oligohydramnios sequence occurs at that time, the more serious the condition can be.
Oligohydramnios occurs in about 4 percent of pregnancies. Not all cases involve a severe decrease in fluid. Oligohydramnios sequence occurs in about 1 in 4,000 births, according to the
Amniotic fluid serves several key purposes for a growing baby. These include:
- aid in the growth and development of the baby’s lungs
- cushion and protect the baby
- help the baby’s muscles and bones develop
- keep the umbilical cord from being compressed, which can affect blood flow and nourishment to the baby
- maintain a constant temperature
- lubricate the fetus’s body parts and prevents them from fusing
Amniotic fluid also has nutrients, hormones, and antibodies that help to fight off infections. At about 36 weeks of pregnancy, a woman will typically have about 1 quart of amniotic fluid in the womb, according to the March of Dimes.
It’s not always possible to determine what causes low levels of amniotic fluid. One potential cause is the continuous leaking of amniotic fluid because the amniotic membranes have ruptured.
After the 20-week point of development, a baby’s urine largely makes up amniotic fluid. The baby’s kidneys are responsible for filtering fluids and producing urine. If the kidneys don’t function properly, the baby can’t make enough urine. This will result in insufficient amount of amniotic fluid. The chain of events resulting from kidney defects (such as malformation, or failure) may lead to oligohydramnios sequence.
Sometimes genetic mutations can affect the kidney’s development. Examples of these abnormalities may include:
- autosomal dominant polycystic kidney disease
- autosomal recessive polycystic kidney disease
- hereditary renal adysplasia
Oligohydramnios sequence most commonly affects male babies. There appears to be a genetic reason for some causes of fetus kidney failure.
A family history of certain renal diseases may increase a woman’s risk of developing oligohydramnios sequence during pregnancy.
Several fetal symptoms can occur when amniotic fluid is too low.
Limited amniotic fluid makes the ammonic cavity smaller than normal. This constricts the fetus, which interferes with normal development and growth. The symptoms of oligohydramnios sequence in a fetus can include facial abnormalities including:
- broad nasal bridge
- widely spaced eyes
- low set ears
When oligohydramnios sequence is caused by fetal kidney failure, urine output after birth is low or absent. Limited amniotic fluid also interferes with normal lung development. If a baby survives through birth, he or she will likely have difficulty breathing.
A doctor can diagnose oligohydramnios sequence with an ultrasound. An ultrasound can detect low levels of amniotic fluid and abnormal kidney development in the fetus.
Leaking amniotic fluid is another possible sign of oligohydramnios sequence. However, leaking doesn’t always occur.
After a baby is born, an X-ray of the lungs and kidneys can help a doctor check for abnormal development. This can help diagnose oligohydramnios sequence in a newborn.
There’s currently no cure for oligohydramnios sequence. Sometimes doctors will perform an amnioinfusion, which involves infusing fluid into the womb. The fluid doesn’t contain the same hormones and antibodies as a mother’s amniotic fluid. But, it does cushion the baby and gives it more time to develop. This infusion can increase the risk for infection and may not be enough to help the lungs develop.
In many cases, the condition can cause a miscarriage. In other cases, the fetus is stillborn or dies shortly after birth. If a baby survives until birth, he or she may need resuscitation.
The prognosis for oligohydramnios sequence is usually very poor. The condition is usually fatal. Because an infant’s lungs don’t properly develop due to lack of amniotic fluid, the infant often experiences respiratory distress.
Effects associated with oligohydramnios sequence include:
- birth defects, such as improperly working kidneys
- miscarriage, or fetal death before 20 weeks of pregnancy
- premature birth, or birth before a baby has developed for 37 weeks
- stillbirth, where a baby dies in the womb before they are 20 weeks old
If a baby is experiencing oligohydramnios sequence, and the baby is developed enough to be born, a doctor may recommend delivering the baby via Cesarean section (C-section). This can allow the baby’s lungs to mature. Survival rates most often depend upon a baby’s lung development. Babies may also experience renal failure. The baby may be able to receive dialysis to act as an artificial kidney and perhaps receive a kidney transplant as they get older.
Unfortunately, there is currently no known prevention for oligohydramnios sequence.