ABSTRACT
Amniotic bands occur as a consequence of a disruption to the amnion with an intact chorion. In most cases, amniotic bands occur without any associated fetal effects, though occasionally a diagnosis of amniotic band syndrome may be made because of associated fetal anomalies. Amniotic band syndrome is believed to be caused by entrapment of fetal parts (usually a limb or digits) in fibrous amniotic membrane while in utero. When the amnion ruptures, fetal parts may protrude into the extra-embryonic coelom and the amniotic membrane can entangle various fetal parts, thereby reducing blood supply and causing congenital abnormalities (typically resulting in amputations). Although no two cases are exactly alike, there are several features that are relatively common: syndactyly, distal ring constrictions, shortened bone growth, limb length discrepancy, distal lymphedema, and congenital bands. Very confusingly, by the time amniotic band syndrome is suspected, the amniotic bands are no longer visible, as the fetal insult probably occurred early in the first trimester.
