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Varicocele and Sperm DNA Fragmentation: New Evidence with Implications for Clinical Practice - Beyond the Abstract

Varicocele has been associated with male infertility since ancient times, but even nowadays, the issue remains debatable. Classically, damage to the reproductive function caused by varicocele is ascribed to testicular hyperthermia due to the loss of the countercurrent mechanism that keeps the testicular temperature 2 degrees Celsius below the core temperature.1

However, recent studies have demonstrated that other factors are also implicated in its pathophysiology in a non-mutually exclusive manner.2 Oxidative stress (OS), caused by excessive production of reactive oxidative species and decreased antioxidant mechanisms, is one such factor. Varicocele has been consistently associated with OS and decreased seminal antioxidant capacity.3 Unchecked excessive ROS can cause single-stranded and/, or double-stranded sperm DNA breaks, commonly referred to as sperm DNA fragmentation.4

Since its introduction in clinical practice, semen analysis (SA) has been the most crucial test for male fertility evaluation. Nonetheless, the widely used WHO cut-off levels for basic semen parameters poorly predict natural pregnancy and ART success.5 In the last two decades, researchers have been looking for better ways of assessing male fertility potential. Recent studies have focused on tests to evaluate sperm function. Given that excessive levels of sperm DNA fragmentation have been linked to decreased pregnancy rates even with assisted reproduction techniques,6 some experts have advocated for measuring SDF levels in clinical practice.7

Emerging data have shown that excessive sperm DNA fragmentation is typically found in semen specimens of infertile men with varicocele. Two meta-analyses on this topic showed that sperm DNA fragmentation rates were higher in men with varicocele than in controls without varicocele, irrespective of the type of assay used to measure it.8,9 Moreover, another systematic review reported that varicocele not only increases SDF rates in men with infertility but also in those with no history of infertility.10

Most male infertility guidelines recommend varicocele repair for infertile men with a palpable disease and abnormal basic SA parameters.11 Improvements in basic SA and pregnancy outcomes after varicocelectomy are consistently observed in these patients.11,12 However, due to the association among varicocele, elevated sperm DNA fragmentation, and poorer reproductive outcomes, an interest emerged regarding the possible beneficial role of varicocelectomy in improving DNA damage.

Several studies have been published on this topic, and data aggregated in four published meta-analyses. The first three reported significant improvements in sperm DNA fragmentation after varicocele treatment.8, 13, 14 However, these analyses were limited due to the inclusion of studies with adolescents, men with subclinical varicocele, and men who had varicocelectomy for reasons other than infertility. In addition, these studies pooled data irrespective of the type of assay used for SDF measurement.

In the most recent systematic review and meta-analysis, we compiled data from 19 studies involving 1070 infertile men with palpable varicocele. We found that varicocelectomy reduced sperm DNA fragmentation rates (all sperm DNA fragmentation assays combined; WMD -7.2%; 95% CI -8.9%; -5.6%; P<0.05) with a moderate effect size (Cohen’s d=0.68; 95% CI: [WMD] 0.77-0.60).15 This finding was confirmed in subanalysis by type of SDF assay (TUNEL, SCSA, SCD, and alkaline Comet). We also showed a similar effect size for microsurgical (WMD -7.2%, 95% CI -8.9%, -5.4%; P<0.05) and open non-microsurgical techniques (WMD -7.1%, 95% CI -12.7%, -1.5%; P<0.05).

The influence of baseline sperm DNA fragmentation levels on the outcomes of varicocelectomy was also assessed in our study. We reported a greater reduction of sperm DNA fragmentation in men with preoperative levels >20% compared to those with levels < 20% (all sperm DNA fragmentation assays combined; WMD -8.3% vs. -3.9%, P<0.05). Furthermore, a meta-regression analysis demonstrated that DNA quality improved after varicocelectomy as a function of preoperative SDF levels (Coefficient: 0.23; 95%CI: 0.07-0.39; P < 0.05).

This study provides level 1 evidence that infertile men with palpable varicocele and elevated sperm DNA fragmentation levels benefit from varicocele repair, thus supporting the latest European Urology Association male infertility guideline and the SFRAG guideline recommendations for varicocelectomy in men with elevated sperm DNA fragmentation levels with otherwise unexplained infertility or who have suffered from failed ART, including recurrent pregnancy loss or failure of embryogenesis and implantation.12,16

Written by: Filipe Tenório Lira Neto, MD1,2 Matheus Roque, MD, PhD3 Sandro C. Esteves, MD, PhD4,5,6

  1. AndrosRecife, Andrology Clinic, Recife, PE, Brazil
  2. Department of Urology, Instituto de Medicina Integral Prof. Fernando Figueira, Recife, PE, Brazil
  3. Department of Reproductive Medicine, São Paulo, SP, Brazil
  4. ANDROFERT, Andrology and Human Reproduction Clinic, Referral Center for Male Reproduction, Avenida Dr. Heitor Penteado, SP, Brazil
  5. Department of Surgery (Division of Urology), University of Campinas (UNICAMP), Campinas, SP, Brazil
  6. Department of Clinical Medicine, Faculty of Health, Aarhus University, Aarhus, Denmark

References:

  1. Neto FT, Bach PV, Najari BB, Li PS, Goldstein M. Spermatogenesis in humans and its affecting factors. Seminars in cell & developmental biology 2016;59:10-26.
  2. Jensen CFS, Ostergren P, Dupree JM, Ohl DA, Sonksen J, Fode M. Varicocele and male infertility. Nature reviews Urology 2017;14:523-33.
  3. Agarwal A, Hamada A, Esteves SC. Insight into oxidative stress in varicocele-associated male infertility: part 1. Nature reviews Urology 2012;9:678-90.
  4. Cho CL, Esteves SC, Agarwal A. Novel insights into the pathophysiology of varicocele and its association with reactive oxygen species and sperm DNA fragmentation. Asian journal of andrology 2016;18:186-93.
  5. Esteves SC. Evolution of the World Health Organization semen analysis manual: where are we? Nature reviews Urology 2022.
  6. McQueen DB, Zhang J, Robins JC. Sperm DNA fragmentation and recurrent pregnancy loss: a systematic review and meta-analysis. Fertility and sterility 2019;112:54-60 e3.
  7. Esteves SC, Agarwal A, Cho CL, Majzoub A. A Strengths-Weaknesses-Opportunities-Threats (SWOT) analysis on the clinical utility of sperm DNA fragmentation testing in specific male infertility scenarios. Transl Androl Urol 2017;6:S734-s60.
  8. Wang YJ, Zhang RQ, Lin YJ, Zhang RG, Zhang WL. Relationship between varicocele and sperm DNA damage and the effect of varicocele repair: a meta-analysis. Reproductive biomedicine online 2012;25:307-14.
  9. Zhang Y, Zhang W, Wu X, Liu G, Dai Y, Jiang H et al. Effect of varicocele on sperm DNA damage: A systematic review and meta-analysis. Andrologia 2022;54:e14275.
  10. Zini A, Dohle G. Are varicoceles associated with increased deoxyribonucleic acid fragmentation? Fertility and sterility 2011;96:1283-7.
  11. Schlegel PN, Sigman M, Collura B, De Jonge CJ, Eisenberg ML, Lamb DJ et al. Diagnosis and Treatment of Infertility in Men: AUA/ASRM Guideline PART II. J Urol 2021;205:44-51.
  12. Minhas S, Bettocchi C, Boeri L, Capogrosso P, Carvalho J, Cilesiz NC et al. European Association of Urology Guidelines on Male Sexual and Reproductive Health: 2021 Update on Male Infertility. European urology 2021;80:603-20.
  13. Qiu D, Shi Q, Pan L. Efficacy of varicocelectomy for sperm DNA integrity improvement: A meta-analysis. Andrologia 2021;53:e13885.
  14. Birowo P, Rahendra Wijaya J, Atmoko W, Rasyid N. The effects of varicocelectomy on the DNA fragmentation index and other sperm parameters: a meta-analysis. Basic Clin Androl 2020;30:15.
  15. Lira Neto FT, Roque M, Esteves SC. Effect of varicocelectomy on sperm deoxyribonucleic acid fragmentation rates in infertile men with clinical varicocele: a systematic review and meta-analysis. Fertility and sterility 2021;116:696-712.
  16. Esteves SC, Zini A, Coward RM. Best urological practices on testing and management of infertile men with abnormal sperm DNA fragmentation levels: the SFRAG guidelines. International braz j urol : official journal of the Brazilian Society of Urology 2021;47:1250-8.
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