Size matters: Total testicular volume predicts sperm count in Tanner V varicocele patients

Abstract

Introduction

It is known the prevalence of varicoceles in adolescent men is 14–29% but there is debate surrounding implications on fertility. As obtaining a semen analysis (SA) may be challenging, there is need for objective tests as measures of fecundity. Our aim was to investigate the relationship between testicular volume differential (TVD), varicocele grade, and total testicular volume (TTV) on seminal parameters including total motile sperm count (TMSC).

Materials and methods

We conducted a retrospective single-center chart review over 14 years of 486 Tanner V adolescent males. Three hundred and four met inclusion of palpable, non-operated left-sided varicocele who underwent at least one SA and ultrasound. Abnormal TMSC was defined by World Health Organization 2010 criteria for minimal reference ranges. Multivariate logistic regression, receiver operating characteristic analysis with Youden J-statistic and descriptive statistics were performed.

Results

Three hundred and four Tanner V adolescents with median age of 18.0 years (18.0–19.0), median TTV of 34.5 cc (28.9, 40.2) and median TMSC of 62.5 million/ejaculate (25.4, 123.4) were evaluated. TTV cutoff of 29.5 cc was found to predict TMSC of <9 million/ejaculate with negative predictive value of 96.2% and odds ratio of 6.08 ([2.13–17.42], p < 0.001). TVD greater than 20% did not reach statistical significance with an odds ratio of 1.66 ([0.41–6.62], p = 0.50).

Discussion

In clinical practice, each patient will need to have an individualized plan. Based on our data, for older adolescents (17 or 18 years) with varicocele and an abnormal TTV, clinicians may have a lower threshold for advising SA, and if unable to obtain, surgical intervention and/or closer surveillance should be stressed. Patients should be informed of their six-fold increase in abnormal SA. Patients with normal TTV should be advised they are at lower risk of having abnormal SA. Younger patients with varicocele and an initial TVD>20%, should be followed closely but intervention delayed until 17 or 18 to better assess TTV. The importance of trending patient data should be emphasized as a single measurement has low predictive value for developing adolescents. Limitations of our study include a retrospective design and the lack of uniform correlation between adolescent SA and paternity.

Conclusions

Total testicular volume less than 29.5 cc increased odds of abnormal semen analysis by over six times and had a negative predictive value of 96.2%. Ultrasound results may be useful for risk stratification and counselling on appropriateness of surgical intervention.

1. Download: Download high-res image (159KB)
2. Download: Download full-size image

Summary Figure. A: ROC curve of TTV as a predictor of abnormal TMSC (defined as <9 million/ejaculate) – all patients. AUC 0.712 [0.611–0.814], sensitivity of 76.1%, specificity of 60.7%, NPV of 96.2%, PPV of 16.2% and Youden J-statistic determined ideal cutoff of 29.5 cc as predictor of abnormal TMSC. B: ROC curve of TTV as a predictor of abnormal TMSC (defined as <9 million/ejaculate) – left testicular hypotrophy subgroup. AUC 0.801 [0.697–0.906], sensitivity of 78.3%, specificity of 76.9%, NPV of 98.2%, PPV of 25.6% and Youden J-statistic determined ideal cutoff of 29.1 cc as predictor of abnormal TMSC.