Normal main portal vein diameter measured on CT is larger than the widely referenced upper limit of 13 mm

We determined mean main portal vein diameter in healthy patients evaluated with CT, compared this value to the "upper limit of normal" reported previously, and evaluated effects of age, sex, height, and BMI on portal vein diameter.

Our cohort of healthy patients underwent abdominal CT as potential renal donors. We excluded patients with evidence of liver or severe cardiac disease. We recorded patients' age, sex, height, weight, and BMI. Patients' main portal vein diameters were measured by fellowship-trained abdominal imagers on non-contrast and post-contrast images in axial and coronal projections at a defined location. A general linear mixed model was used for analysis.

191 patients with 679 main portal vein measurements were included in the analysis. Mean main portal vein diameter was 15.5 ± 1.9 mm; this value was significantly different from the upper limit of normal of 13 mm commonly referenced in the literature (95% CI: 2.22-2.69 mm higher, p < 0.0001). Portal vein diameter does not vary significantly when measured on axial vs. coronal images. On average, post-contrast main portal veins were 0.56 mm larger compared to non-contrast, (95% CI: 0.40-0.71 mm, p < 0.0071). Patient height and BMI are positively correlated with MPV diameter.

Normal mean portal vein diameter measured on CT was significantly larger (mean 15.5 mm) than the accepted upper limit of 13 mm. Contrast-enhanced main portal veins are significantly larger (0.56 mm) than unenhanced. Sex, height, and BMI significantly affect main portal vein diameter.