Reversed end-diastolic flow in the umbilical artery at 10-14 weeks of gestation is associated with absent pulmonary valve syndrome.

OBJECTIVE: To determine the incidence of reversed end-diastolic flow (REDF) in the umbilical artery in high-risk first-trimester pregnancies and evaluate associated conditions.

METHODS: This was a prospective evaluation of the umbilical artery Doppler waveforms of 614 consecutive high-risk pregnancies between 10 and 14 weeks of gestation, to determine those with REDF. The associated anomalies and characteristics of these fetuses were then investigated.

RESULTS: In 278/614 (45.3%) fetuses, there was positive end-diastolic flow in the umbilical artery; in 331/614 (53.9%) end-diastolic flow was absent and in 5/614 (0.8%) there was REDF. Three of the five fetuses with REDF had tetralogy of Fallot (TOF) with absent pulmonary valve syndrome (APVS) and a patent ductus arteriosus, and all three showed signs of cardiac failure, with reversed blood flow in the ductus venosus during atrial systole and generalized skin edema. Another fetus had a large ventricular septal defect and the remaining fetus had agenesis of the ductus venosus. Three fetuses had trisomy 18 and one had trisomy 13.

CONCLUSIONS: REDF in the umbilical artery is very rare in early pregnancy and mostly occurs in association with major fetal vascular anomalies and cardiac defects, particularly TOF with APVS and patent arterial duct. We propose that the patency of the arterial duct in TOF with APVS leads to heart failure with subsequent demise early in pregnancy. Therefore, the frequent absence of the arterial duct observed in APVS in later pregnancy is more likely to be a result of early selection than a prerequisite for the development of this lesion as has been proposed previously.