The clinical significance of antenatal detection of discordant umbilical arteries.

OBJECTIVE: To evaluate the clinical significance of the antenatally detected discordant umbilical arteries (UAs).
METHODS: Women with singleton gestations undergoing sonographic evaluations were examined for the presence of discordant UAs. Transverse and longitudinal diameters as well as the area of both UAs were measured. Doppler flow velocity waveforms were recorded from both arteries. Macroscopic and microscopic examination of the umbilical cord was performed after delivery and the area of each artery was measured. Mann-Whitney U test and Spearman rank correlation were used for statistical purposes.
RESULTS: Data are presented as median (range). Discordance between UAs was found in 14 of 1012 women who underwent sonographic examinations. The vessel diameters and areas differed significantly between the discordant UAs (diameter 2.9 [1-4.3] versus 4.5 [3.8-6.5] mm, P < .001; area 6.6 [0.78-14.5] versus 16.25 [11.33-33.16] mm2, P < .001). A significant difference between UA size was confirmed after delivery (area 1.68 [0.9-3.06] versus 4.17 [1.12-13.8] mm2, P < .005). The difference in the area of the UAs in utero and at microscopic examination correlated significantly (r = .94, P < .05). In all cases, the resistance index was higher in the smaller artery than in the larger artery (0.71 [0.59-0.8] versus 0.6 [0.48-0.75] P < .01). Abnormal insertion of the umbilical cord or an abnormality of the placenta was present in eight cases. Perinatal death occurred only in a trisomic infant born at 24 weeks' gestation.
CONCLUSION: The clinical significance of discordant UAs is that newborns are generally in good condition at birth and placental anomalies are common in this group of parturients. Abnormal Doppler velocimetry of the smaller UA should be taken with caution, because it does not seem to be associated with poor perinatal outcome.