Echo-Doppler measurements of portal vein and superior mesenteric artery blood flow in humans: inter- and intra-observer short-term reproducibility.

The reproducibility of echo-Doppler measurements of portal vein and superior mesenteric artery blood flow has not been extensively studied. In the present study, two groups of subjects were examined to test inter- and intra-observer reproducibility. Each study population consisted of 15 nonportal hypertensive and 15 portal hypertensive subjects. With a standardized technique, the crosssectional area and velocity of blood flow in the portal vein and superior mesenteric artery were recorded in triplicate by skilled operators. The flow volume of each vessel was calculated by multiplying the cross-sectional area by the velocity of blood flow. The measurements were performed in a blind fashion over a 60 min period. The reproducibility of measurements was assessed by calculation of intraclass correlation coefficients and coefficients of variation. The intra-observer intraclass correlation coefficient was 0.77 for portal vein blood flow and 0.84 for superior mesenteric artery blood flow, suggesting good reproducibility. The intra-observer coefficient of variation was 11 and 9%, respectively. In contrast, the interobserver intraclass correlation coefficient was calculated to be 0.49 for portal blood vein blood flow and 0.57 for superior mesenteric artery blood flow, indicating fair reproducibility. In addition, the interobserver coefficients of variation were calculated to be 20 and 18%, respectively. These data suggest that intra-observer reproducibility in echo-Doppler measurements of portal vein and superior mesenteric artery blood flow is acceptable but inter-observer reproducibility is not. Examination by a single operator, rather than multiple operators, is therefore advisable. Even when measurements are performed by a single investigator an approximate variance of 10% in the measurement in a single subject should be expected.