Prenatal assessment of Wharton's jelly in umbilical cords with single artery.

Objective: To investigate whether the amount of Wharton's jelly in non-malformed fetuses with a single umbilical artery is different from that of fetuses with a normal umbilical cord.
Methods: We evaluated patients with singleton pregnancies, non-malformed fetuses and single umbilical artery undergoing sonographic evaluation at a gestational age ranging from 19 to 41 weeks' gestation. The cross-sectional areas of the umbilical cord and of the umbilical vessels were measured. The amount of Wharton's jelly was calculated by subtracting from the total cross-sectional area of the umbilical cord the areas of the artery and of the vein. The umbilical cord cross-sectional area, the umbilical artery and vein areas as well as the amount of Wharton's jelly were plotted on previously published nomograms.
Results: Twenty-two patients met the inclusion criteria. The umbilical cord cross-sectional area was within the normal range in 20 (90.1%) cases. The umbilical artery and vein areas were above 2 standard deviations from the mean in 20 cases and in 11 cases (50%), respectively. The amount of Wharton's jelly was below 2 standard deviations from the mean in all cases. An abnormal insertion of the umbilical cord (marginal, velamentous) was present in five cases (22.7%).
Conclusions: A reduction of Wharton's jelly is frequently present in cases of single umbilical artery. The increased perinatal morbidity and mortality observed in cases of single umbilical artery, even in the absence of congenital or chromosomal abnormalities, could be in part the consequence of a reduced amount of Wharton's jelly.