Evaluation of Inferior and Superior Vena Cava and the Vena Cava Ratio in Growth Restricted Fetuses

Objective: To evaluate the changes in the diameters of superior vena cava (SVC) and inferior vena cava (IVC) and to measure the ratio between SVC and IVC in growth-restricted fetuses and compare these results with normally grown fetuses. Methods: Twenty-three consecutive patients with fetal growth restriction (FGR) (Group I) and 23 pregnant gestational age-matched controls (Group II) between 24 and 37 weeks of gestation were enrolled in the study between January 2018 and October 2018. The diameter of the SVC and IVC from inner wall to inner wall was measured in all patients by sonographic examination. The ratio between the diameter of the SVC and IVC was also measured in each patient to eliminate the gestational age factor. We have named this ratio the “vena cava ratio” (VCR). All parameters were compared between the two groups. Results: The diameter of the SVC was significantly greater in the fetuses with FGR (2.6–7.7 [5.4]) than in controls (3.2–5.6 [4.1]; P =.002; P <.01). The diameter of the IVC was significantly less in the fetuses with FGR (1.6–4.5 [3.2]) than in controls (2.7–5 [3.7]; P =.035; P <.05). The VCR was between 1.1 and 2.3 and the median value was 1.8 in Group I. The VCR was between 0.8 and 1.7 and the median value was 1.2. VCR was significantly higher in fetuses with FGR (P =.001 P <.01). Conclusion: This study shows that VCR is higher in fetuses with growth restriction. Further studies are needed to clarify the association between VCR and antenatal prognosis and postnatal results. © 2023 American Institute of Ultrasound in Medicine.