Validity of transabdominal sonography in the detection of a two-vessel umbilical cord

To determine the validity of transabdominal ultrasound in the detection of a two-vessel and a three-vessel umbilical cord.

The ultrasound and pathology databases were collated between January 1, 1999, and December 31, 2000. Only those cases with ultrasound and pathology information concerning the number of vessels in the umbilical cord were included for analysis (group 1). In addition, 27 cases with a two-vessel umbilical cord were included from the ultrasound database before January 1, 1999, for which pathologic information was also obtained (group 2).

A total of 1295 ultrasound/pathology reports were entered from January 1, 1999, through December 31, 2000; 268 cases did not have complete information, leaving 1027 for analysis (group 1). The visualization rate of the number of vessels in the umbilical cord increased from 15 to 17 weeks' gestation (74.1-97.6%; P <.001). The visualization rate remained stable from 17.0 to 35.9 weeks' gestation, and then declined to 83.3% (P <.01). The sensitivity, specificity, positive predictive value, and negative predictive value for the diagnosis of a two-vessel umbilical cord were 85%, 99.7%, 85%, and 99.7%, respectively.

The detection rate of either a two-vessel or three-vessel umbilical cord is best achieved between 17 and 36 weeks' gestation. In the majority of two-vessel umbilical cords that were called three-vessel, an appropriate transverse image of the umbilical cord was not obtained.