The association of single umbilical artery with cytogenetically abnormal pregnancies.

The clinical significance of the absence of one of the two umbilical arteries (single umbilical artery) lies in its association with congenital malformations. Whether this association includes cytogenetic abnormalities is less clear. A retrospective review of all detected chromosomally abnormal pregnancies at the University of Maryland was carried out. Of 109 cytogenetically abnormal pregnancies, the number of umbilical cord vessels could be documented in 53 cases. Six (11.3%) had a single umbilical artery. A single umbilical artery was noted in two of nine fetuses (22.2%) with trisomy 18 and in two of six fetuses (33.3%) with trisomy 13. Two other unusual chromosomal constitutions were noted in cases of a single umbilical artery. None of the 11 fetuses with sex chromosome abnormalities (including eight with monosomy X) had a single umbilical artery. Of 18 fetuses with trisomy 21, none had a single umbilical artery. This study suggests that a single umbilical artery is preferentially associated with certain karyotypic abnormalities and that trisomy 21 does not appear to be associated with a single umbilical artery.