Amniotic band syndrome refers to a condition in which bands develop from the inner lining of the amnion. The amnion is the sac that surrounds the baby in the womb. As the baby develops in the womb, the bands may attach to and affect the development of different areas of the body. This may result in constriction of the affected area or even amputation. The signs and symptoms vary greatly depending on the area(s) of the body involved and may include: shortened or absent digits (fingers and/or toes) or limbs (arms and/or legs), an opening in the abdomen through which various abdominal organs can protrude (abdominal wall defects), protrusion of a portion of the brain and its surrounding membranes through a skull defect (encephalocele), and cleft lip and/or palate. In most instances, the cause of amniotic bands remains unknown. Researchers have suggested two main theories to explain the development: the extrinsic theory and the intrinsic theory. The extrinsic theory states that amniotic band syndrome occurs due to factors found outside of the developing baby (externally); the intrinsic theory states that amniotic band syndrome occurs due to factors found within the baby (internally). Treatment differs depending on the severity of the condition and the areas of the body affected and may include surgery, physical therapy, and occupational therapy.