The development of high venous velocity at the fetal umbilical ring during gestational weeks 11–19

Abstract

Objective To determine the occurrence of high venous velocities at the umbilical ring in the normal early second trimester, based on the assumption that a narrow umbilical ring may cause obstruction and increased venous blood velocity at the abdominal wall.Design Cross-sectional study. Setting Hospital antenatal clinic.Population One hundred and one low risk singleton pregnancies speci®cally recruited for the study.Methods Ultrasound was used at 11±19 weeks to determine the diameter and velocity in the umbilical vein at the fetal end of the cord and at the inlet through the abdominal wall. Outcome measures 10th, 50th and 90th centiles were estimated for the time-averaged maximum velocity in the cord and at the abdominal inlet. The increase of velocity as the blood entered the abdominal wall was calculated in percent of the velocity in the cord.Results During weeks 11-12 there was hardly any difference between blood velocity in the umbilical vein at the umbilical ring and that in the cord. From week 13 onwards it was increasingly common to ®nd blood acceleration at the umbilical ring of 50±500%. Velocity increment .50% was found in 0/12 fetuses (0%) at 11±12 weeks, 5/20 (25%) at 13±14 weeks, and in 21/28 (75%) at 17±19 weeks. Conclusions Blood velocity is higher in the umbilical vein at the abdominal wall than the cord, particularly after 13 weeks of gestation. If acceleration of blood velocity at the umbilical ring is a sign of a narrow inlet, it seems that a progressive tightening occurs during the second trimester.

Relationship between the umbilical cord coiling index and the umbilical blood flow at 11–13 weeks of gestation

“…Skulstad et al . investigated the umbilical venous velocity increment at the fetal abdominal wall during gestational weeks 11–19 and demonstrated that the blood velocity was higher in the umbilical vein at the abdominal wall than in the free loop of the cord, especially after 13 weeks . On the other hand, a small tendency toward a reduced relative velocity increment at the umbilical ring occurring in association with increasing gestational age from 20 to 40 weeks of gestation has been reported .…”

“…The velocity increment at the level of the umbilical ring was calculated as the difference between the velocity at the umbilical ring and that found in the free loop presented as the percentage of the velocity in the free loop, as reported by Skulstad …”

“…However, pathological umbilical cord coiling, such as hypercoiled cords, is often observed in stillborn and pathological fetuses delivered in the second trimester. Although the association between the strength of umbilical cord coiling and the umbilical blood flow after the second trimester has been evaluated in several studies, it remains unclear when and how hypercoiled cords are formed and whether coiling affects blood flow in the umbilical cord.…”

Amnioinfusion and Bed Rest May Effectively Improve the Insufficient Circulation of the Umbilical Cord in Pregnant Women With Hyper-Coiled Cord and Oligohydramnios

“…Hyper-coiled cord tends to lead to fetal hypoxia due to an external force such as labor or a fetal movement more often than a normal coiled cord [1]. Several studies have shown that hyper-coiled cords are correlated with poor perinatal outcomes such as low birth weight, meconium staining of amniotic fluid at birth and fetal growth restriction [2][3][4]. In our previous study of intrauterine fetal death after the second trimester, fetal death was found to be caused by a hyper-coiled cord in 25.9% (21/81) of cases.…”