Amniotic bands have been proposed as the cause of a variety of congenital anomalies that may be divided into three groups, depending on whether they affect the limbs, head, or body wall. Defects of one or more limbs may include simple amputations of fingers or toes, partial syndactyly,constriction rings that encircle a limb, or reduction defects (amputations)that affect a significant portion of the involved arm or leg. Oblique facial clefts, encephaloceles, and neural tube-like defects are among the abnormalities associated with bands affecting the head. Defects of the body wall may involve the chest (thoracoschisis, extrathoracic heart) or the abdomen (gastroschisis).

The developing embryo sits protected within two cavities. Like a balloon within a balloon, the amniotic cavity sits within the larger chorionic cavity. As the amnion expands, it eventually presses against the chorion, obliterating the early extraembryonic coelom. Usually this fusion of the two membranes is complete by about...

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