Fetal heart monitoring in detection velamentous insertion of the umbilical cord.

Velamentous insertion of the umbilical cord is a high-risk obstetrical condition that is rarely diagnosed before delivery of the placenta. The fetal mortality rate from this condition has been estimated to be as high as 70 percent. Criteria used to aid in the diagnosis of this condition include (1) vaginal bleeding accompanied by fetal heart irregularities, (2) vaginal blood determined to be of fetal origin, (3) palpation of vasoprevia through a dilated cervix, (4) visualization of vasoprevia through the amnioscope, and (5) marked fetal bradycardia when the membranes are unruptured and there is no evidence of vaginal bleeding.