Reversible arterial redistribution in a fetus with true umbilical cord knot: case report and review of literature.

Umbilical cord knot (UCK) affects around 1% of pregnancies and tightening of UCK is a very rare and highly unpredictable complication of pregnancy that can lead to fetal demise or neonatal death. The majority of authors agree that very little could be done to prevent fetal deaths in pregnancies with undiagnosed tight UCK. We herein report the case of a 39-year-old, gravidity five, parity three, pregnant woman at 40 weeks and five days age of pregnancy, whose pregnancy evolved without complications and who was admitted to hospital for the management of the birth. Although the last ultrasound examination before birth showed a reversible arterial redistribution in the fetus dependent on the postural status of the pregnant women and other factors associated with umbilical cord knot were present, the diagnosis was missed because of the factors' non-specificity. After a spontaneous labor without complications a dead male fetus, weight 3300 g, without heartbeat, Apgar score 0 was delivered. Macroscopic and microscopic findings confirmed that the cause of neonatal death was asphyxia caused by a tight UCK. The aim of our paper is to present the dramatic outcome of a pregnancy with a fetus with a tight umbilical cord knot (UCK), to bring to attention the signs that suggested the diagnosis, and to review the literature on this subject.