Peak systolic velocity, not vein size, predicts abnormal sperm count in adolescent Tanner V patients with primary left varicocele

Varicocele severity has traditionally been associated with larger testicular vein size, but the true relationship to decreased fertility remains debatable. In clinical practice, the largest testicular vein diameter is an often-used parameter to screen for potential surgical intervention, even though current research provides weak support for this. More recent studies have found venous reflux patterns and total testicular volume (TTV) to be significantly associated with total motile sperm count (TMSC). This study compares largest testicular vein size and arterial flow rates, assessing the predictive value of each for identifying patients at risk for reduced semen analysis (SA) parameters.

We conducted a retrospective, single-institution chart review over 14 years of 487 Tanner V adolescents. Patients were included if they had a palpable, primary left-sided varicocele and underwent at least one SA and scrotal Doppler ultrasound (SDUS) to assess vein diameter and arterial blood flow including peak systolic and end-diastolic velocities. Abnormal TMSC was defined by WHO 2010 criteria. Descriptive statistics, ROC analysis and univariate as well as multivariate logistic regression analyses were performed using SPSS.

148 Tanner V adolescent males were included. Mean age ± SD was 18.24 ± 1.38 years. Median diameter of largest vein on US was 3.5 mm (IQR 3.1-4.6), median peak systolic velocity (PSV) of the left testicular artery was 10.4 cm/s (IQR 9.1-12.5), median end-diastolic velocity (EDV) of the left testicular artery was 5.1 cm/s (IQR 4.3-5.9), and median value of PSV/EDV was 2.1 (IQR 1.8-2.3), with a median TMSC of 37.4 million sperm (IQR 15.8-84.2). On ROC analysis regarding prediction of abnormal TMSC (<9 million sperm/ejaculate), left testicular PSV was found to have the greatest AUC at 0.73 (95 % CI 0.62-0.85) with Youden index analysis determining an ideal cutoff of 10.22 cm/s. Based on this cutoff, the positive predictive value for identifying a patient with abnormal TMSC was 23.6 %, corresponding to a number needed to screen of approximately 4 patients to identify one with abnormal sperm parameters. Left testicle largest vein diameter was found to have an AUC of 0.48. On univariate logistic regression, PSV <10.22 cm/s was predictive of abnormal TMSC (OR: 5.51 [1.84-16.46], p = 0.002, which persisted on multivariate logistic regression with adjustment for age (OR: 5.49 [1.83-16.43], p = 0.002).

Left testicular PSV was the parameter most significantly correlated with TMSC in this cohort. A PSV <10.22 cm/s was found to be predictive of an abnormally low TMSC. There was no significant predictive value of larger veins for abnormal TMSC. When assessing varicocele severity by US, left testicular artery PSV should be measured to help stratify future fertility risk and provide important context regarding shared decision making about potential surgical intervention.