Amniotic constriction bands are strands of fluid-filled sacs that surround a baby in the womb. They may cause a congenital (present from birth) deformity of the arms, legs, fingers, or toes.

Amniotic constriction bands are caused by a type of damage to a part of the placenta called the amnion. The placenta carries blood to a baby still growing in the womb. Damage to the placenta can prevent normal growth development.

Damage to the amnion may produce fiber-like bands that can trap the arms, legs, fingers, or toes of the fetus. These bands reduce blood supply to the areas and cause them to develop abnormally.

Amniotic constriction bands are relatively rare.

The severity of the deformity can vary widely from only one toe or finger being affected to an entire arm or leg missing or being severely underdeveloped. Symptoms may include:

• Abnormal gap in the face (if it goes across the face, it is called a cleft)
• All or part of an arm or leg missing (congenital amputation)
• Defect of the abdomen or chest wall (if band is located in those areas)
• Permanent band or indentation around an arm, leg, finger, or toe

The health care provider can diagnose this condition during a physical exam. The disease is usually diagnosed at birth.

Treatment widely varies. Often, the deformity is not severe and no treatment is needed. In more serious cases, major surgery may be needed to reconstruct all or part of an arm or leg.

How well the infant does depends on the severity of the disease. Most cases are mild and the outlook for normal function is excellent. More severe cases have more guarded outcomes.

Complications can include complete or partial loss of function of an arm or a leg. Congenital bands affecting the hand often cause the most problems.