284 Umbilical vein flow in fetal growth restriction versus small for gestational age fetuses

Abstract

Umbilical vein flow (Quv) is known to be reduced in fetal growth restriction (FGR) compared to appropriate for gestational age (AGA) controls. Our objective was to assess whether Quv is decreased between FGR subgroups meeting Delphi criteria (FGR-D) vs small for gestational age (SGA) controls. This is a prospective observational study of 52 FGR fetuses (EFW < 10th%ile) and 136 AGA controls (controls obtained in Trieste, Italy). FGR was divided into FGR-D (EFW < 10th%ile with abnormal Dopplers, UA PI > 95th%ile or CPR < 5th%ile or an EFW < 3rd %ile; n=24) vs SGA (3-10th %ile with normal Dopplers; n=28) according to the 2016 International Society of Obstetricians and Gynecologists guidelines. Quv was calculated from the average maximum velocity (Tmax) within the vein, obtained by pulsed wave Doppler of a vessel running parallel to the ultrasound beam, and the inner diameter of a vessel running at 90° to it as previously described. Quv (mL/min) = 0.5 × Tmax × π(D/2)ˆ2 × 60. Quv was further corrected for fetal size by EFW and by abdominal circumference (AC). Independent samples t-test and chi squared analysis were used. Gestational age at the time of analysis was similar between all groups (FGR-D 34.5 vs SGA 35.8, p= .43 and FGR 35.6 vs AGA 35.2, p=.27). Quv was confirmed to be significantly lower in FGR vs AGA controls (210.9 ml/min vs 247.9 ml/min, p=.003). Quv was also significantly lower in FGR-D vs SGA (188.3 ml/min vs 230.4 ml/min, p=.04). This remained significantly different between FGR vs AGA when adjusted by AC (Quv/AC), but not by EFW (Table 1). Quv normalized by AC and EFW were not different between FGR-D vs SGA (Table 2). We found that absolute Quv was significantly reduced in FGR compared to AGA controls, as previously shown. Absolute Quv was reduced between FGR-D and SGA groups consistent with the Delphi criteria identifying those that are pathologically versus constitutionally small. When corrected by EFW or AC, no differences were found between FGR groups likely reflecting that Quv is proportional to fetal size. (Funded by the Perelman Family Foundation)View Large Image Figure ViewerDownload Hi-res image Download (PPT)