Fig. 1

Ultrasonography at 25 weeks of gestation. a An approximately 4.2-cm-long thickening of Wharton jelly was noted about 1.5 cm away from the placental cord insertion(arrows), b and the cross-sectional view revealed that the thickened Wharton jelly wrapped around three blood vessels: the inner diameter of the umbilical vein was approximately 0.65 cm; the inner diameter of the umbilical artery was approximately 0.35 cm; and pulse Doppler had probed c the arterial and d venous blood flow spectrums, respectively. e The cross-sectional view of the middle part of the umbilical cord revealed only two umbilical arteries with blood flow signals. The umbilical vein was broadened, with an inner diameter of approximately 1.9 cm. f The vertical section showed that the broadened umbilical vein was approximately 20 cm long, and the blood flow in it was extremely slow. g The inner diameter of the widest part of the intra-abdominal segment of the umbilical vein was approximately 0.74 cm. h No abnormality of the umbilical artery was found in the intra-abdominal segment