Effect of Bariatric Surgery on Male Infertility: An Updated Meta-Analysis and Literature Review.

Purpose: We aimed to perform a meta-analysis to assess the evolution of sperm parameters and some sex hormones in obese males with idiopathic infertility who underwent bariatric surgery.

Materials and methods: We systematically searched MEDLINE and Embase databases for studies that documented sperm parameters and sex hormones before and after surgery.

Results: Twelve studies have been included with a total of 285 patients. The heterogeneity was deemed moderate, with an I² value of 28%. The random effects model analysis indicated a statistically significant negative association between weight loss surgery and sperm concentration. The standardized mean difference (SMD) was -5.44, with a 95% confidence interval (CI) ranging from -7.65 to -3.22. The p-value was <0.0001. Twelve articles recorded the sperm volume before and after undergoing bariatric surgery. The analysis revealed no statistically significant alteration in sperm volume following surgery (SMD=-0.16, 95% CI -0.53-0.22; p=0.42). We assessed the total sperm count available in seven studies. The analysis did not prove any significant difference between groups (SMD=12.29, 95% CI -15.01-39.58; p=0.38). Evaluated in five studies, semen pH did not evolve significantly (SMD=-0.02, 95% CI -0.12-0.09; p=0.76). Also, total motility did not improve significantly (SMD=0.61, CI -2.86-4.09; p=0.73), and the included studies had a low heterogeneity (I²=29%). Following bariatric surgery, there was a significant increase in levels of both total testosterone and sex hormone-binding globulin (SHBG) (SMD=-6.40, 95% CI -9.12 to -3.67, p<0.00001 for total testosterone and -22.22, 95% CI -26.11 to -18.33, p<0.00001 for SHBG).

Conclusions: Our data suggests that bariatric surgery does not provide any benefits in terms of sperm parameters. Obesity likely affects fertility through processes that are not well understood.