Amniotic Band Syndrome (ABS)
What is amniotic band syndrome?
Amniotic band syndrome (ABS) is a group of birth defects affecting the arms, legs, abdomen, chest, and head, that are caused by amniotic bands (strands of the amniotic membrane) inside the uterus. While inside the womb, any part of the fetus’ body can become tangled in these bands which tighten around the particular body part, sometimes resulting in loss of an arm, leg, fingers, or toes. The severity of the defect is variable, ranging from loss of a finger to the intestines being outside of the body. ABS is rare and is seen in one out of 1,200 to 15,000 babies.
How is this condition managed during pregnancy?
Most of the time, the bands cannot be seen with ultrasound but the diagnosis is suspected based on the pattern of the birth defect. If ABS is suspected, a thorough ultrasound of the fetal body is performed to look for other defects. Sometimes a detailed ultrasound of the fetus’ heart will be done. Usually, ABS is not caused by genetic problems but if the diagnosis is not clear, an amniocentesis will be done to test the fetus’ DNA. If the bands are seen to be wrapping around the umbilical cord they can be cut by using a small camera that is inserted into the uterus but this is often not necessary.
Many pregnancies complicated by ABS will deliver prematurely. Usually, labor does not need to be induced and patients can try to have a vaginal delivery.
How is this condition managed after delivery?
All babies are examined once they are born and sometimes they will require surgery to correct the defects or prevent them from getting worse. The prognosis for the baby depends on the specific defect. Infants who have defects of the arms and legs sometimes need prosthetics and generally have a good prognosis.