2. Agarwal A., Majzoub A., Parekh N.et al. Schematic Overview of the Current Status of Male Infertility Practice. World J Mens Health. 2019 Jul 12.

3. Jarow, J.P., Sharlip, I.D., Belker, A.M. et al. Best practice policies for male infertility. J Urol. 2002; 167: 2138–2144.

4. A.-Meguid T.A., Al-Sayyad A., Tayib A. et al. Does varicocele repair improve male infertility? An evidence-based perspective from a randomized, controlled trial. European Urology. 2011;59:455–461.

5. Baazeem A., Belzile E., Ciampi A. et al. Varicocele and male factor infertility treatment: a new meta-analysis and review of the role of varicocele repair. Eur Urol. 2001;60:796–808.

6. Kroese A.C., de Lange N.M., Collins J., Evers J.L. Surgery or embolization for varicoceles in subfertile men. Cochrane Database Syst Rev. 2012;10:CD000479.

7. Evers J.H., Collins J., Clarke J. Surgery or embolisation for varicoceles in subfertile men. Cochrane Database Syst Rev. 2009;(1):CD000479.

8. Redmon J.B., Carey P., Pryor J.L. Varicocele–the most common cause of male factor infertility? Hum Reprod Update. 2002;8:53–58.

9. Dada R., Venkatesh S., Kumar K.et al. Re: Decreased sperm DNA fragmentation after surgical varicocelectomy is associated with increased pregnancy rate: M. Smit, J.C. Romijn, M.W. Wildhagen, J.L. Veldhoven, RF. Weber and G.R. Dohle. J Urol. 2010;183:270–274. J Urol. 2010; 184: 1577 (author reply 1578).

10. Bungum M., Humaidan P., Spano M. et al. The predictive value of sperm chromatin structure assay (SCSA) parameters for the outcome of intrauterine insemination, IVF and ICSI. Hum Reprod. 2004;19:1401–1408.

11. Samplaski M., Jarvi K. Prognostic factors for a favorable outcome after varicocele repair in adolescents and adults. Asian Journal of Andrology. 2016;18:217–221.

12. Ding H., Tian J., Du W. et al. Open non-microsurgical, laparoscopic or open microsurgical varicocelectomy for male infertility: a meta-analysis of randomized controlled trials. BJU Int. 2012;110(10):1536–1542.

13. Çayan S., Shavakhabov S., Kadioǧlu A. Treatment of palpable varicocele review in infertile men: a meta-analysis to define the best technique. J Androl. 2009;30(1):33–40.

14. Schlesinger M.H., Wilets I.F., Nagler H.M. Treatment outcome after varicocelectomy. A critical analysis. Urol Clin North Am. 1994;21:517–529.

15. Ollandini G., Trombetta C., Mazzon G. et al. Should older patients be offered varicocoele correction to improve their fertility? Andrology. 2014;2(3):402–407.

16. Cantoro U., Catanzariti F., Lacetera V. et al. Percentage change of FSH value: new variable to predict the seminal outcome after varicocelectomy. Andrologia. 2015;47:412–416.

17. Samplaski M., Yu Ch., Kattan M. et al. Nomograms for predicting changes in semen parameters in infertile men after varicocele repair. Fertility and Sterility. 2014;102(1):68–74.

18. Phillips B., Ball C., Sackett D. et al. Oxford Centre for Evidence-based Medicine Indexes of Evidence. Updated by Jeremy Howick March 2009.

19. Palmisano F, Moreno-Mendoza D, Ievoli R. et al. Clinical factors affecting semen improvement after microsurgical subinguinal varicocelectomy: which subfertile patients benefit from surgery? Ther Adv Urol. 2019;11:1756287219887656.

20. Sun, X.L., Wang, J.L., Peng, Y. et al. Bilateral is superior to unilateral varicocelectomy in infertile males with left clinical and right subclinical varicocele: A prospective randomized controlled study. International Urology and Nephrology. 2018;50(2):205–210.

21. Alshehri F.M., Akbar M.H., Altwairgi A.K. et al. Preoperative duplex ultrasound parameters predicting male fertility after successful varicocelectomy. Saudi Med J. 2015;36(12):1439–1445.

22. Shabana W., Teleb M., Dawod T. et al. Predictors of improvement in semen parameters after varicocelectomy for male subfertility: A prospective study. Can Urol Assoc J. 2015;9(9–10): E579-82.

23. Johnson D., Harnisch B., Zganjar A. et al. Mp74-13 Predictors of success after microscopic subinguinal varicocelectomy. J Urol. 2015;193(4):e944.

24. Kadioglu T.C., Aliyev E., Celtik M. Microscopic varicocelectomy significantly decreases the sperm DNA fragmentation index in patients with infertility. Biomed Res Int 2014;2014:695713.

25. Bozhedomov V.A., Lipatova N.A., Alexeev R.A. et al. The role of the antisperm antibodies in male infertility assessment after microsurgical varicocelectomy. Andrology. 2014;2:847–855.

26. Baazeem A., Boman J.M., Libman et al. Microsurgical varicocelectomy for infertile men with oligospermia: Differential effect of bilateral and unilateral varicocele on pregnancy outcomes. BJU International, 2009;104(4):524–528.

27. Elbendary M.A., Elbadry A.M. Right subclinical varicocele: how to manage in infertile patients with clinical left varicocele? Fertil Steril 2009;92:2050–2053.

28. Libman J., Jarvi K., Lo K., Zini A. Beneficial effect of microsurgical varicocelectomy is superior for men with bilateral versus unilateral repair. J Urol 2006;176:2602–2605.

29. Kiuchi H., Koga M., Hirai T. et al. Predictive factors associated with successful varicocele repair a study of 139 infertile men with valicocele. Nihon Hinyokika Gakkai Zasshi. Jpn J Urol 2005;96:480–486.

30. Pasqualotto F.F., Lucon A.M., de Goes P.M., Sobreiro B.P., Hallak J. et al. Relationship between the number of veins ligated in a varicocelectomy with testicular volume, hormonal indexs and semen parameters outcome. J Assist Reprod Genet. 2005;22:245–249.

31. Scherr D., Goldstein M. Comparison of bilateral versus unilateral varicocelectomy in men with palpable bilateral varicoceles. J Urol. 1999;162:85–88.

32. Takahara M., Ichikawa T., Shiseki Y., Nakamura T., Shimazaki J. Relationship between grade of varicocele and the response to varicocelectomy. Int J Urol. 1996;3:282–285.

33. Steckel J., Dicker A.P., Goldstein M. Relationship between varicocele size and response to varicocelectomy. J Urol. 1993;149:769–771.

34. Almekaty K., Zahran M.H., Zoeir A. et al. The role of artery-preserving varicocelectomy in subfertile men with severe oligozoospermia: a randomized controlled study. Andrology. 2019;7(2):193–198.

35. Çayan S., Şahin S., Akbay E. Paternity Rates and Time to Conception in Adolescents with Varicocele Undergoing Microsurgical Varicocele Repair vs Observation Only: A Single Institution Experience with 408 Patients. J Urol. 2017;198(1):195–201.

36. Ogreden E., Oguz U., Cirakoglu A., Demirelli E., Benli E., Yalcin O. Comparison of response to treatment of unilateral and bilateral varicocelectomy. Turkish Journal of Medical Sciences, 2017;47(1):167–171.

37. Kimura M., Nagao K., Tai T. et al. Age is a significant predictor of early and late improvement in semen parameters after microsurgical varicocele repair. Andrologia. 2017;49(3).

38. Zhang J.W., Xu Q.Q., Kuang Y.L. et al. Predictors for spontaneous pregnancy after microsurgical subinguinal varicocelectomy: a prospective cohort study. Int Urol Nephrol. 2017;49(6):955–960.

39. Wang H., Wang X., Fu D. et al. Does varicocele grade predict the postoperative changes of semen parameters following left inguinal micro-varicocelectomy? Asian Journal of Urology. 2015;2(3):163–166.

40. Peng J., Zhang Zh., Cui W. et al. Spontaneous pregnancy rates in Chinese men undergoing microsurgical subinguinal varicocelectomy and possible preoperative factors affecting the outcomes. Fertility and Sterility. 2015;103(3):635–639.

41. Awati Sh.M. Factors predicting early improvement in semen parameters following varicocele surgery. Int J Reprod Contracept Obstet Gynecol. 2014;3(4):1027–1032.

42. Enatsu N., Yamaguchi K., Chiba K. et al. Clinical Outcome of Microsurgical Varicocelectomy in Infertile Men with Severe Oligozoospermia. 2014;83(5):1071–1074.

43. Huang H.C., Huang S.T., Chen Y. et al. Prognostic factors for successful varicocelectomy to treat varicocele associated male infertility. Reprod Fertil Dev 2014;26:485–490.

44. Baker K., McGill J., Sharma R. et al. Pregnancy after varicocelectomy: impact of postoperative motility and DFI. Urology. 2013;81:760–776.

45. Giagulli V.A., Carbone M.D. Varicocele correction for infertility: which patients to treat? Int J Androl. 2011;34(3):236–241.

46. Chen S.S., Chen L.K. Predictive factors of successful varicocelectomy in infertile patients. Urol Int 2011;86:320–324.

47. Zheng Y.Q., Gao X., Li Z.J. et al. Efficacy of bilateral and left varicocelectomy in infertile men with left clinical and right subclinical varicoceles: a comparative study. Urology. 2009;73:1236–1240.

48. Kondo Y., Ishikawa T., Yamaguchi K. et al. Predictors of improved seminal characteristics by varicocele repair. Andrologia. 2009;41:20–23.

49. Ishikawa T., Fujisawa M. Effect of age and grade on surgery for patients with varicocele. Urology 2005;65:768–772.

50. Fujisawa M., Ishikawa T., Takenaka A. The efficacy of bilateral varicocelectomy in patients with palpable bilateral varicoceles: comparative study with unilateral varicocele. Urol Res. 2003;31:407–409.

51. Yoshida K., itahara S., Chiba K., Horiuchi S., Sumi S., Moriguchi H. Predictive indicators of successful varicocele repair in men with infertility. Int Journ of Fertil and Wom Medicine. 2000;45(4):279–284.

52. Grasso M., Lania C., Castelli M. et al. Low-grade left varicocele in patients over 30 years old: the effect of spermatic vein ligation on fertility . BJU International. 2000;85(3):305–307.

53. Pierik FH., Vreeburg JT., Stijnen T. et al. Improvement of sperm count and motility after ligation of varicoceles detected with colour Doppler ultrasonography. Int J Androl. 1998;21(5):256–260.

54. Nieschlag E., Hertle L., Fischedick A.et al. Update on treatment of varicocele: counselling as effective as occlusion of the vena spermatica. Human Reproduction. 1998;13(8):2147–2150.

55. Grasso M., Lania C., Castelli M. et al. Bilateral varicocele: impact of right spermatic vein ligation on fertility. J Urol. 1995;153:1847–1848.

56. Marks J.L., McMahon R., Lipshultz L.I. Predictive parameters of successful varicocele repair. J Urol. 1986;136:609–612.

57. Okuyama A., Itatani H., Mizutani S. et al. Factors affecting fertility after varicocelectomy. Eur Urol. 1980;6(4):214–217.

58. Ghanaie M.M., Asgari S.A., Dadrass N. et al. Effects of Varicocele Repair on Spontaneous First Trimester Miscarriage. Urology. 2012;9(2).

59. Hassanzadeh Nokashty K., Yavarikia P., Ghaffari A. et al. Effect of age on semen parameters in infertile men after varicocelectomy. Ther Clin Risk Manag. 2011;7:333–336.

60. Madhusoodanan V., Blachman-Braun R., Patel P. et al. Preoperative follicle-stimulating hormone: A factor associated with semen parameter improvement after microscopic subinguinal varicocelectomy. Can Urol Assoc J. 2020;14(1): E27–E31.

61. Yazdani M., Hadi M., Abbasi H. et al. Efficacy of Varicocele Repair in Different Age Groups. Urology. 2015;86(2):273–275.

62. Hsiao W., Rosoff J.S., Pale J.R. et al. Older age is associated with similar improvements in semen parameters and testosterone after subinguinal microsurgical varicocelectomy. J Urol. 2011;185(2):620–625.

63. Resorlu B., Kara C., Sahin E. et al. The significance of age on success of surgery for patients with varicocele. Int Urol Nephrol. 2010;42:351–356.

64. Zini A., Boman J., Baazeem A. et al. Natural history of varicocele management in the era of intracytoplasmic sperm injection. Fertil Steril. 2008;90:2251–2256.

65. Dohle G.R. Does varicocele repair result in more spontaneous pregnancies? A prospective randomized trial. Int J Andr Oct. 2010;33(Suppl. 1):21–38.

66. O’Brien J.H., Bowles B., Kamal K.M. Microsurgical varicocelectomy for infertile couples with advanced female age: natural history in the era of ART. J Androl. 2004;25:939–943.

67. AL-Ghazo M.A., Ghalayini I.F., AL-Azab R.S. et al. Does the duration of infertility affect semen parameters and pregnancy rate after varicocelectomy? A retrospective study. Clin Urol. 2011;37(6):745–750.

68. Zorba U.O., Sanli O.M., Tezer M. et al. Effect of infertility duration on postvaricocelectomy sperm counts and pregnancy rates. Urology. 2009;73:767–771.

69. Ates E., Ucar M., Keskin MZ. et al. Preoperative neutrophil-to-lymphocyte ratio as a new prognostic predictor after microsurgical subinguinal varicocelectomy. Andrologia. 2019;51(2).

70. Chen S.S. Predictive factors of successful redo varicocelectomy in infertile patients with recurrent varicocele. Andrologia 2014;46:738–743.

71. Al-Adl A.M., El-Karamany T., Issa H. et al. The influence of antisperm antibodies, intratesticular haemodynamics and the surgical approach to varicocelectomy on seminal variables. Arab J Urol. 2014;12(4):309–317.

72. Samplaski M.K., Lo K.C., Grober E.D. et al. Varicocelectomy to «upgrade» semen quality to allow couples to use less invasive forms of assisted reproductive technology. Fert and Ster. 2017;108(4):0015-0282.

73. Smit M., Romijn J.C., Wildhagen M.F. et al. Decreased sperm DNA fragmentation after surgical varicocelectomy is associated with increased pregnancy rate. J Urol. 2013;189(1 Suppl): S. 146–150.

74. Cayan S., Erdemir F., Ozbey I. et al. Can varicocelectomy significantly change the way couples use assisted reproductive technologies? J Urol. 2002;167:1749–1752.

75. Matkov T.G., Zenni M., Sandlow J. et al. Preoperative semen analysis as a predictor of seminal improvement following varicocelectomy. Fertil Steril 2001;75:63–68.

76. Kamal K.M., Jarvi K., Zini A. Microsurgical varicocelectomy in the era of assisted reproductive technology: influence of initial semen quality on pregnancy rates. Fertil Steril. 2001;75:1013–1016.

77. Li F., Yamaguchi K., Okada K. et al. Significant improvement of sperm DNA quality after microsurgical repair of varicocele. Syst Biol Reprod Med. 2012;58:274–277.

78. Abdelbaki S.A., Sabry J.H., Al-Adl A.M. et al. The impact of coexisting sperm DNA fragmentation and seminal oxidative stress on the outcome of varicocelectomy in infertile patients: A prospective controlled study. Arab J Urol. 2017;15(2):131–139.

79. Ni K., Steger K., Yang H. et al. A comprehensive investigation of sperm DNA damage and oxidative stress injury in infertile patients with subclinical, normozoospermic, and astheno/oligozoospermic clinical varicocele. Andrology. 2016;4(5):816–824.

80. Dadfar M., Ahangarpour A., Habiby A. et al. Pre-operative serum index of inhibin B as a predictor of spermatogenesis improvement after varicocelectomy. Urol J. 2010;7(2):110–114.

81. Ozden C., Levent O., Suleyman B. et al. Effect of varicocelectomy on serum inhibin B indexs in infertile patients with varicocele. Scand JUr and Nephr. 2008;42(5):441–443.

82. Fujisawa M., Dobashi M., Yamasaki T. et al. Significance of serum inhibin B concentration for evaluating improvement in spermatogenesis after varicocelectomy. Hum Reprod. 2001;16(9):1945–1949.

83. Goren M.R., Erbay G., Ozer C. et al. Can We Predict the Outcome of Varicocelectomy Based on the Duration of Venous Reflux? Urology. 2016;88:81–86.

84. Mehraban D., Taghdiri M., Nategh S. et al. Ultrasonic predictors of improved seminal parameters after bilateral laparoscopic varicocelectomy. Int Urol and Nephr. 2012;44(4):1121–1125.

85. Hussein A.F. The role of color Doppler ultrasound in prediction of the outcome of microsurgical subinguinal varicocelectomy. J Urol. 2006;176(5):2141–2145.

86. Ortapamuk H., Tekdogan U.Y., Naldoken S. et al. Hemodynamic evaluation of varicocele: the role of scrotal scintigraphy and Doppler ultrasonography in the prediction of postoperative seminal improvement. Annals of Nuclear Medicine. 2005;19(7):529–534.

87. Wang Q., Yu Y., Liu Y., Wang L. Outcome of varicocelectomy on different degrees of total motile sperm count: A systematic review and meta-analysis. Sys Biol in Rep Med. 2019;65(6):430–436.

88. Niu Y., Wang D., Chen Y. et al. Comparison of clinical outcome of bilateral and unilateral varicocelectomy in infertile males with left clinical and right subclinical varicocele: A meta-analysis of randomised controlled trials. Andrologia. 2018;50(9):e13078.

89. Ou N., Zhu J., Zhang W. et al. Bilateral is superior to unilateral varicocelectomy in infertile men with bilateral varicocele: Systematic review and meta-analysis. Andrologia. 2019;51(11):e13462.

90. Asafu-Adjei D., Judge C., Deibert C.M. et al. Systematic Review of the Impact of Varicocele Grade on Response to Surgical Management. J Urol. 2020;203(1):48–56.