Children's Hospital Colorado

Amniotic Band Syndrome

What is amniotic band syndrome?

Amniotic band syndrome, or ABS, refers to a condition caused by damage to the amnion, the sac that surrounds the baby while they are in the womb. When this sac is damaged, fibrous strings or bands can enter the amniotic fluid. Occasionally, these bands may wrap around parts of a baby's body, hindering blood flow and growth.

In most cases of ABS, amniotic bands wrap around the arms, fingers, legs or toes. Some rare cases involve the head or waist of a baby. Damage to the amnion can occur early in pregnancy development (between 6 and 18 weeks of pregnancy) or after a fetal procedure. The earlier the bands form, the more likely it is for these bands to result in serious complications. Current studies estimate that ABS occurs in approximately 1 out of every 1,200 live births.

At Children’s Hospital Colorado, our Colorado Fetal Care Center is one of the country’s top centers for diagnosing and treating ABS.

What causes amniotic band syndrome?

Amniotic band syndrome usually occurs when fibrous bands enter the uterus following a partial rupture (break) of amnion. This can occur spontaneously early in pregnancy or, rarely, after a fetal procedure.

ABS is considered a sporadic event or a spontaneous accident that occurs during early development of the amnion, placenta and fetus. This means there is no known cause. The condition is not inherited and there is no increased risk of this condition happening again in a future pregnancy.