Velamentous insertion of umbilical cord: An abnormal condition in which the umbilical cord does not insert into the placental mass but, instead, traverses the fetal membranes before it inserts into the umbilical cord. The main danger is vasa previa, a condition in which the blood vessels may be lodged between the fetus and the entrance to the birth canal. The unprotected vessels may rupture at any time during pregnancy, causing fetal hemorrhage and death.
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Last Editorial Review: 5/13/2016