Umbilical vein blood flow in fetuses with normal and lean umbilical cord

Objective To evaluate whether umbilical vascular coiling is correlated with the umbilical vein blood flow profile and to investigate if this is different between fetuses with a lean and those with a normal umbilical cord. Methods Consecutive women with a singleton gestation who delivered at term and who underwent an ultrasound examination within 24 h from delivery were studied. Umbilical cord and vessel areas were calculated. Umbilical vein blood flow parameters were obtained by digital color Doppler velocity profile integration. After delivery, the umbilical coiling index was calculated. Results One hundred and sixteen women were studied. Twelve (10.3%) had a lean umbilical cord (area < 10th centile). A significant correlation was found between the umbilical coiling index and the umbilical vein blood flow (r = 0.67, P < 0.001). A significant difference between fetuses with and without a lean cord was found in terms of: umbilical coiling index (0.18 +/- 0.08 vs. 0.29 +/- 0.09, P < 0.005), cord area (87.6 <plus/minus> 5.1 mm(2) vs. 200.6 +/- 34.6 mm2, P < 0.001). Wharton's jelly amount (25.7 <plus/minus> 10.3 mm(2) vs. 122.1 +/- 33.4 mm(2), P < 0.001), umbilical vein blood flow (93.7 <plus/minus> 17.8 ml/kg per min vs. 126.0 +/- 23.4 ml/kg per min, P < 0.001), and umbilical vein blood flow mean velocity (6.6 <plus/minus> 2.7 cm/s vs. 9.0 +/- 3.6 cm/s, P < 0.05). The Proportion of fetuses with an umbilical vein blood flow < 80 ml/kg per min was higher when the cord was lean than when it teas normal (25% vs. 1.9%, P < 0.01). Conclusions Lean umbilical cords differ from normal cords not only from a structural point of view but also in the umbilical vein blood flow characteristics. This could explain the increased incidence of intrapartum complications and fetal growth restriction among fetuses with a lean and/or hypocoiled cord.