The aim of the study was to compare the values of the sonographic inferior vena cava/ aorta index obtained with the transducer placed in the median line and right anterior axillary line.Material and methodsThe study enrolled 45 volunteers, including 33 women, aged 22.5 ± 1.26 with a negative history of circulatory and renal diseases. The study consisted in a sonographic assessment and measurement of the inferior vena cava and aorta by placing the transducer in the anterior median line and right anterior axillary line. The value of the inferior vena cava/aorta index was obtained by calculating the ratio of the diameters of the inferior vena cava and aorta. The diameter measurements were taken by placing the ultrasound transducer in the anterior median line and right anterior axillary line. Two examiners performed the measurement three times and used convex probes of 3.5–5 MHz. Additionally, the subjects’ weight, height and arterial blood pressure were taken.ResultsFollowing a statistical analysis with the use of STATISTICA software, the following values of the inferior vena cava/aorta index were obtained: in the anterior median line – 1.43 ± 0.21, and in the right anterior axillary line – 1.285 ± 0.19. There was no statistically significant difference between the measurements obtained by the two examiners (p = 0.17). A strong correlation was noted between the inferior vena cava/ aorta indices calculated in both sites of transducer placement, which was irrespective of the examiners (the correlation coefficient: r = 0.61 and r = 0.71). The study indicate that the inferior vena cava/aorta index measured in the right anterior axillary line is a simple and reproducible method for determining the body fluid status; the examinations conducted in both sites may be used interchangeably. Further studies are needed to determine reference values for the inferior vena cava/aorta index measured in the right anterior axillary line.