Ultrasound assessment of testicular volume - An interobserver variability study

Background: Ultrasonography measurement of the testicles and subsequent calculation of the testicular volume is recommended as a part of a standard scrotal ultrasound examination. The interobserver variability of testicular volume measurement has implications for surgical recommendations. Therefore, this study aimed to investigate the interobserver variability in the measurement of testicular volume. Methods: Interobserver variability was established by comparing testicular measurements performed by two observers on the same patient during the same clinical appointment. The observers were blinded to each other's measurements. Testicular volume was calculated using the Lambert formula: length x width x height x 0.71. A total of three observers, A, B and C, participated in the study. The observers had between 4 to 20 years’ experience with scrotal ultrasound examinations. Results: In total, 24 patients’ were included (48 testicles). The patient´s mean age was 43 years (range 19-75 years). The overall mean right testicular volume was 19.8 ml (range 7.3–31.6 ml), and the left was 20.1 ml (range 7.1–36.1 ml). The interclass correlation coefficient (ICC) between observer A and B was excellent (ICC= 0.98, CI:0.92–0.99), between observer A and C, was excellent (ICC=0.91, CI: 0.77–0.97) and between B and C good (ICC=0.82, CI:0.51–0.93). Conclusion: Variability in estimating testicular volume is low, with interobserver agreement ranging from good to excellent. Ultrasound provides a highly reproducible tool to determine testicular volume.