Effect of umbilical vein blood flow on perinatal outcome of fetuses with lean and/or hypo-coiled umbilical cord

To evaluate the effect of umbilical vein (UV) blood flow measured by color-directed pulsed-wave Doppler on perinatal outcome of fetuses with lean and/or hypocoiled umbilical cord after 24 weeks of gestation. Two hundred and forty-four women with singleton fetus after 24 weeks of gestation were studied. Umbilical cord area, umbilical vessel cross-sectional area and antenatal umbilical coiling index (UCI) were calculated and compared with Doppler parameters including UV blood flow volume in ml/min/kg, UV peak systolic velocity in cm/s, and umbilical artery pulsatility index. Thirty-eight (15.5\%) fetuses had lean umbilical cord (area < 10th percentile). A significant difference between fetuses with and those without lean cord was found in terms of: UCI (0.17 +/- A 0.06 vs. 0.35 +/- A 0.08, P < 0.001), cord cross-sectional area (89.6 +/- A 11.7 vs. 198.7 +/- A 33.7 mm(2), P < 0.001), Wharton's jelly amount (36.5 +/- A 11.2 vs. 125.2 +/- A 34.1 mm(2), P < 0.001), UV blood flow (83.4 +/- A 15.8 vs. 131.0 +/- A 19.8 ml/min/kg, P < 0.001), and UV blood flow mean velocity (8.6 +/- A 3.7 vs. 12.1 +/- A 2.8 cm/s, P < 0.05). A significant positive correlation was found between antenatal UCI and UV blood flow (r = 0.73, P < 0.001). Fetuses with lean and/or hypo-coiled umbilical cord showed a noticeable decrease in UV blood flow of sufficient magnitude that could affect fetal growth, and this could explain the higher prevalence of fetal intrapartum complications in growth-restricted fetuses.