Strangulation of the umbilical cord by amniotic bands: report of 6 cases and literature review.

The amniotic band syndrome is the triad of amnion-denuded placenta; fetal attachment to or entanglement by amniotic remnants; and fetal deformation, malformation, or disruption. Theories of pathogenesis and etiology of the syndrome are discussed. Amniotic bands occur in 1 of every 5000-15,000 births and are demonstrable in 1-2% of malformed infants. Nearly 10% of cases include umbilical cord strangulation. Six cases of umbilical cord strangulation by amniotic bands are presented, and 57 previously reported cases are reviewed. Two of the 63 were liveborn and 61 were stillborn, 3 of whom died intrapartum. Thirty had associated fetal abnormalities. Five were from multiple gestations. Outcome of the co-twin was determined by its presence within the same amniotic sac. Four fetuses beyond 28 weeks had short cords and were the only malformed fetuses in this age group. The earlier in gestation that amniotic bands form, the greater the likelihood of associated fetal abnormalities. All but 2 of 28 less than 32 weeks and only 4 of 35 greater than 32 weeks were malformed. A marked male predominance was noted in the former group, perhaps because the larger size and/or more vigorous movements of male fetuses promote early amnion rupture.