Skulstad Svein Magne, Kiserud Torvid, Rasmussen Svein
Department of Obstetrics and Gynaecology, Bergen University Hospital, Bergen, Norway.
Prenat Diagn. 2002 Nov;22(11):1022-7. doi: 10.1002/pd.462.
To determine the degree of constriction of the umbilical vein at the abdominal wall in the second half of pregnancy.
A total of 283 low-risk singleton pregnancies were recruited for a cross-sectional study, and examined once at 20-40 weeks of gestation. Two sets of ultrasound measurements of the umbilical vein were taken: one at the fetal end of the umbilical cord and another at the inlet through the abdominal wall, the umbilical ring. The diameter was determined as an average of >or=5 repeat measurements. The blood velocity was recorded at the same site.
The time-averaged maximum venous blood velocity in the cord was low (mean 13-19 cm/s during 20-40 weeks of gestation), and the corresponding mean diameter 3.6-8.2 mm. In contrast, the mean of the venous blood velocity at the umbilical ring was 34-41 cm/s and the diameter was 2.8-5.9 mm during the same period. Of 191 pairs of observations, 41 (21%) had a velocity increment of >or=300 %, which corresponds to a diameter reduction to half or more at the umbilical ring.
Constriction of the umbilical ring is a common phenomenon in the second half of pregnancy.
确定妊娠晚期腹壁处脐静脉的狭窄程度。
共纳入283例低风险单胎妊娠进行横断面研究，在妊娠20 - 40周时进行一次检查。对脐静脉进行两组超声测量：一组在脐带胎儿端，另一组在通过腹壁的入口即脐环处。直径通过≥5次重复测量的平均值来确定。在同一部位记录血流速度。
脐带中时间平均最大静脉血流速度较低（妊娠20 - 40周期间平均为13 - 19 cm/s），相应的平均直径为3.6 - 8.2 mm。相比之下，同期脐环处静脉血流速度平均为34 - 41 cm/s，直径为2.8 - 5.9 mm。在191对观察结果中，41对（21%）的血流速度增量≥300%，这对应于脐环处直径缩小至一半或更多。
脐环狭窄是妊娠晚期的常见现象。
