Amniotic band syndrome in pregnancy
AMNIOTIC band syndrome (ABS) can occur when the inner layer of the placenta, called the amnion, is damaged during pregnancy. The United States-based Johns Hopkins Medicine says if this happens, thin strands of tissue (amniotic bands) have formed inside the amnion.
“These fibre-like bands tangle around the developing foetus, restricting blood flow, thus affecting the growth of certain body parts. This can cause congenital deformities of limbs. In some cases, strands can tangle so tightly around the limbs of a foetus that they amputate them. Amniotic band syndrome is usually diagnosed at birth, but can sometimes be detected in the womb by ultrasound,” Johns Hopkins said.
The US National Library of Medicine lists these facts about ABS.
Causes
Amniotic bands are thought to be caused by damage to a part of the placenta called the amnion (or amniotic membrane). The placenta carries blood to a baby still growing in the womb. Damage to the placenta can prevent normal growth and development.
Damage to the amnion may produce fibre-like bands that can trap or compress parts of the developing baby. These bands reduce blood supply to the areas and cause them to develop abnormally.
However, some cases of ABS deformity may be caused by reduced blood supply without any signs of bands or damage to the amnion. There have also been rare cases that seem to be due to genetic defects.
Symptoms
The severity of the deformity can vary widely, from a small dent in a toe or finger to an entire body part missing or being severely underdeveloped. Symptoms may include:
•Abnormal gap in the head or face (if it goes across the face, it is called a cleft)
•All or part of a finger, toe, arm, or leg missing (congenital amputation)
•Defect (cleft or hole) of the abdomen or chest wall (if band is located in those areas)
•Permanent band or indentation around an arm, leg, finger, or toe.
Exams and tests
The health-care provider can diagnose this condition during prenatal ultrasound, if it is severe enough, or during a newborn physical exam.
Treatment
Treatment varies widely. Often, the deformity is not severe and no treatment is needed. Surgery while the baby is in the womb may help improve outcomes in some cases, but it is not yet clear which babies will benefit. Some cases improve or resolve prior to birth. In more serious cases, major surgery may be needed to reconstruct all or some of a body part. Some cases are so severe that they cannot be repaired.
Outlook (Prognosis)
How well the infant does depends on the severity of the condition. Most cases are mild and the outlook for normal function is excellent. More severe cases have more guarded outcomes.
Possible complications
Complications can include complete or partial loss of function of a body part. Congenital bands affecting large parts of the body cause the most problems. Some cases are so severe that they cannot be repaired.
