Gunter De Win

Objectives To assess the evolution of the Testicular Atrophy Index (TAI) in adolescent boys with and without a left varicocele with special attention for the currently postulated cut‐off value of 20%. Subjects and Methods During 2015–2019, 364 adolescent boys aged 11–16 years were recruited. Genital examination and scrotal ultrasonography were repeatedly performed (≥4 month intervals). Testicular volume (TV) was calculated using the Lambert formula (length × width × height × 0.71). TAI was calculated using the formula: [(TVright − TVleft)/TVlargest (right, left)] × 100. Results The final study population comprised 239 participants, 161 (67.36%) controls and 78 (32.64%) adolescent boys with left varicocele. The mean ( sd ) number of measurements per participant was 3.82 (1.08). A TAI of ≥20% at first measurement occurred in 9.94% and 35.90%, respectively. Of these, only 31.25% and 46.43% had a TAI of ≥20% at the last measurement, respectively. Nevertheless, the risk of ending up with a TAI of ≥20% was significantly higher if a TAI of ≥20% was recorded at first measurement ( P = 0.041 and P = 0.002, respectively). The normalisation rate did not differ significantly between the groups ( P = 0.182). Normalisation occurred most frequently in Tanner Stages III and IV. Normalisation was mostly (≥74%) due to catch‐up growth of the left testis, in contrast to growth retardation of the right testis, in both groups. The TAI seems to be a fluctuating parameter. Conclusion A TAI of ≥20% is a phenomenon seen in boys with and without varicocele but is more common in boys with varicocele. Although normalisation of a high TAI is frequently seen, both adolescent boys with and without a left varicocele who have an initial TAI of ≥20% have a higher risk of a TAI of ≥20% in the future. As the TAI is a fluctuating parameter during pubertal development, it's use as indicator for varicocelectomy based on a single measurement during pubertal development is questioned.