Association of fetal venous diameter and volume flow measurements with late-onset fetal growth restriction: A prospective case-control study

This study investigates the diagnostic utility of venous diameter (d) and volume flow (Q) measurements of the umbilical vein (UmbV), ductus venosus (DV), inferior vena cava (IVC), and subdiaphragmatic vestibulum (SDV) in fetuses with late-onset fetal growth restriction (FGR).

This prospective case-control study included 54 singleton pregnancies (27 late-onset FGR and 27 gestational age-matched controls) between 33 and 37 weeks of gestation. Venous diameters and Doppler-derived volume flow measurements of the UmbV, DV, IVC, and SDV were assessed using ultrasonography. Correlation, linear regression, and receiver operating characteristic analyses were performed.

All venous diameter and volume flow parameters were significantly lower in fetuses with FGR than in controls (P ≤ 0.003 for all). Venous parameters were positively correlated with estimated fetal weight (EFW). In multivariable analysis, UmbV-d (B = 1.425, 95% confidence interval CI 0.635-2.214, P = 0.001) and IVC-d (B = 2.212, 95% CI 0.944-3.481, P = 0.001) remained independently associated with EFW. UmbV-d showed the highest discriminative performance for identifying FGR (area under the curve [AUC] 0.947, 95% CI 0.894-0.999, P < 0.001). Among flow parameters, UmbV-Q demonstrated the highest AUC (0.858, 95% CI 0.756-0.960, P < 0.001), whereas only IVC-Q remained independently associated with EFW. A combined model including UmbV-d and IVC-d achieved an AUC of 0.972.

Fetal venous diameter and volume flow measurements were significantly reduced in late-onset FGR. UmbV-d demonstrated the strongest association with EFW and the highest discriminative performance, whereas UmbV-Q was the best-performing flow parameter. Combined assessment of UmbV-d and IVC-d demonstrated promising discriminative performance; however, larger studies are required to determine whether these measurements provide information beyond conventional fetal biometry.