Amniotic Band Syndrome is a congenital disorder that develops when fibrous amniotic bands constrict the digits, arms and legs of babies while still in the womb. This can result in swollen extremities (congenital lymphedema) and can result in extremities being amputated whilst still in the womb (congenital amputation).

It has been theorized that a partial rupture of the amniotic sac causes ABS, which results in the fibrous, ruptured material encircling parts of the fetus. As the fetus grows to term, the fibers become progressively tighter. ABS can also produce cleft lips, cleft palates, hemangioma (benign tumours), clubfeet and clubhands.