OP21.08: Relationship between umbilical vein constriction, intra‐abdominal dilatation and perinatal outcome

Abstract

Objectives: Intra-abdominal umbilical vein (UV) distension is sometimes seen in cases of fetal demise. We hypothesize that such a UV distension may be a post-stenotic dilatation due to an umbilical ring constriction. Here we explore whether a stricture of the UV is related to UV distension and to adverse outcome. Methods: Referred high-risk pregnancies underwent Doppler assessment that included assessment of the UV at the umbilical ring. UV blood velocity >90th percentile at this site and gestational age (GA) was defined as a UV constriction. An intra-abdominal UV diameter >90th percentile was defined as distension. Pregancies were followed up with repeat observations. Placental weight and fetal outcome were noted. Results: Thirteen fetuses (11 singletons and two twins) that had UVstricture but no major anomalies were included. Median GA at first examination for 10 survivors was 27 (19–36) weeks and for three fetal deaths 24 (19–24) weeks. There was a median of 5 (range, 2–9) observations in each fetus (total 66). Nine of 13 fetuses had both UV constriction and dilatation at first examination. UV constriction >97.5th percentile and GA <24 weeks were related to birth weight <5th percentile (P < 0.05) and fetal death (P < 0.05). In subsequent observations UV constriction varied to values <90th percentile in seven of 13 fetuses. In the rest (6/13) the UV constriction resolved for the rest of pregnancy. In all cases a relatively large placental weight was seen. Furthermore, a UV distension that extended from the abdominal wall to the ductus venosus was related to increased placental weight (P < 0.05). Conclusions: UV stricture at the umbilical ring seems to be commonly linked to intra-abdominal UV distension. This supports the assumption that the UV distension is often a post-stenotic dilatation. We speculate that it is the venous constriction that restricts hemodynamic responsiveness and carries the risk of complications (rather than the distention).