Prenatal diagnosis of the two‐vessel cord: implications for patient counselling and obstetric management

Abstract

The study was designed to investigate the implications of the sonographic diagnosis of the two-vessel umbilical cord for patient counselling and pregnancy management. Retrospective analysis was carried out of prenatal findings and pregnancy outcomes when a two-vessel cord was diagnosed in utero. Eighty-two fetuses each with a single umbilical artery were diagnosed by ultrasound. Ten were aneuploid, including nine with visible structural defects and one with early onset intrauterine growth retardation. Of the remaining 72, 31 had other anomalies diagnosed postnatally; 27 of these had structural defects detected on ultrasound examination. However, in nine of these 27 sonographically abnormal fetuses, one or more major structural defects were missed by ultrasound examination. Among the 45 chromosomally normal fetuses with no visible defects on scan, four had anomalies diagnosed after birth. Among the chromosomally normal singletons, six of 22 with other anomalies seen on scan and seven of 38 with no other visible defects on scan had intrauterine growth retardation. Among chromosomally normal twins, one of two with other anomalies seen and two of five appearing otherwise normal had intrauterine growth retardation; one twin set was delivered at 23 weeks after the demise of both twins. Karyotyping is recommended whenever a two-vessel cord is seen in association with symmetric intrauterine growth retardation or any other defect. The fetus diagnosed with a two-vessel cord and any other anomaly by ultrasound often has additional structural defects not seen on scan. The fetus with an isolated two-vessel cord on scan seldom has unrecognized major anomalies, but is at risk for intrauterine growth retardation.

Frequency and nature of structural anomalies in fetuses with single umbilical arteries.

“…This rate of anomalous conditions is similar to that found in prior studies by Catanzarite and coworkers 8,9 but is considerably higher than the rate found in several other studies. [5][6][7] When an isolated SUA is identified on a prenatal sonogram, the parents should be counseled about the significance of this finding.…”

“…Other authors, however, have found a far higher frequency of anomalies or aneuploidy in neonates with a prenatal sonographic diagnosis of isolated SUA. 8,9 In these two reports, five of 56 neonates (9%) with apparently isolated SUA at prenatal sonography were found to be abnormal at birth. We undertook a study of prenatally diagnosed SUA to assess the frequency, nature, and sonographic detection of anomalies.…”

Sonographic assessment of the umbilical cord

“…Although the umbilical cord can be easily visualized on prenatal sonogram, there is a discrepancy between the theoretic ultrasound accuracy and actual reliability to detect SUA reflected in the range of positive predictive values of 65 to 94%. 25,27 Due to lower than expected ultrasound detection of SUA, there is a discrepancy in number of neonates born with an SUA and associated anomaly diagnosed postnatally compared to those in the antenatal period. The proportion of identified fetuses with associated malformations diagnosed prenatally would rise postnataly from 26 and 43 to 43% and 50%, respectively.…”

“…The proportion of identified fetuses with associated malformations diagnosed prenatally would rise postnataly from 26 and 43 to 43% and 50%, respectively. 27,28 In addition to associated fetal anomalies with an SUA, an intrauterine fetal growth restriction (IUGR) was observed more frequently in aneuploid than euploid fetuses, 28% vs 15-20%, respectively.…”

“…27,28 Concomitantly, 25-29% of the neonates with an iSUA would have a birth weight less than 2500 gm. 29,30 The difference in birth weights was even more pronounced in multifetal gestation in which one of the twins would have a SUA.…”