Amniotic band syndrome
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Amniotic band syndrome (ABS) is a congenital disorder caused by entrapment of fetal parts (usually a limb or digits) in fibrous amniotic bands while in utero.
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Epidemiology
Amniotic Band Syndrome (ABS) affects approximately 1:1200 live births. It is also believed to be the cause of 178 in 10,000 miscarriages. Up to 50% of cases have other congenital anomalies including cleft lip, cleft palate, and clubfoot deformity. Hand and finger anomalies occur in up to 80%.
Pathophysiology
ABS occurs when the inner fetal membrane (amnion) ruptures without injury to the outer membrane (chorion). Fibrous bands from the ruptured amnion float in the amniotic fluid and can entangle the fetus, reducing blood supply and causing congenital abnormalities. In some cases a complete "natural" amputation of a digit(s) or limb may occur before birth or the digit(s) or limbs may be necrotic (dead) and require surgical amputation following birth.
Features
- Constriction rings around the digits, arms and legs
- Swelling of the extremities distal to the point of constriction
- Amputation of digits, arms and legs
A strong relationship between ABS and clubfoot exists. A 31.5% of associated clubfoot deformity and ABS can be correlated with 20% occurring bilaterally. Other abnormalities found with ABS include: clubhands, cleft lip, and/or cleft palate, and hemangioma.
Diagnosis
At birth, the characteristic asymmetric amputations and constriction rings are seen.
Treatment
Treatment depends on the deformity found. Plastic and reconstructive surgery is often needed. Physical and occupational therapy may be needed long term.
Prognosis
In 50% of the ABS cases the baby does not survive. It is believed to be the cause of 178 in 10,000 miscarriages.
Prevention
If diagnosed in utero, surgical lysis of amniotic bands can prevent the deformities.