The Influence of Different Bariatric Surgeries on Male Sex Hormones and Semen Parameters Among Infertile Obese Male Patients: An Observational Study

43 obese infertile men saw testosterone rise and semen motility improve after bariatric surgery — but zero pregnancies in 12 months

Journal: BMC Surgery | Published: 2026-05-23 | Type: Prospective Case Series | PMID: 42177498 Authors: Mahmoud A et al. — General and Laparoscopic Surgery & Department of Andrology, Sexology and STDs, Cairo University Hospital, Egypt Funding/COI: Funding not listed. Authors declare no competing interests.

Summary

A prospective case series from Cairo University followed 43 obese infertile men (BMI ≥ 35) through one of three bariatric surgeries — sleeve gastrectomy, one-anastomosis gastric bypass (OAGB), or Roux-en-Y gastric bypass — measuring hormones and semen at baseline and at 3, 6, and 12 months post-op. Testosterone rose and estradiol fell significantly; semen motility, progressive motility, vitality, and morphology all improved. Despite these laboratory improvements, not a single pregnancy was recorded in the 12-month follow-up window.

Claims

• Significant weight loss at all three follow-up timepoints (p ≤ 0.003 at each)
• Semen motility, progressive motility, vitality, and percentage of abnormal forms all improved (all p ≤ 0.003)
• Total serum testosterone increased significantly (p ≤ 0.003)
• Estradiol (E2) decreased significantly (p ≤ 0.003)
• FSH, LH, and prolactin changes were statistically insignificant
• Zero pregnancies recorded across all 43 participants over 12 months

Study Quality

This is a prospective case series — a step above a retrospective chart review, but well below an RCT. There is no control group, no randomization, and no blinding. The 43 participants were divided across three distinct surgical procedures without pre-specified subgroup allocation, meaning the study cannot determine whether sleeve gastrectomy, OAGB, or Roux-en-Y produces different fertility outcomes — a question the paper's own cited literature identifies as a key gap. The p-value threshold of ≤ 0.003 is reported uniformly for all significant findings, which suggests a Bonferroni-style correction was applied to a multi-timepoint design, but the statistical analysis plan is not described with enough clarity to confirm this.

The full-text sections supplied with this paper appear to contain substantial passages from a different publication — a 2018 systematic review with PROSPERO registration CRD42018096955, a search performed June 21–26, 2018, and three reviewers identified by initials (LCM, MR, RS). This is either a serious editorial error in the journal's production process or a data ingestion artifact. Readers relying on the full text should verify the manuscript directly via BMC Surgery.

Red Flags

• No control group. A case series cannot distinguish surgery effects from weight loss achieved by other means, time effects, or regression to the mean.
• Three surgeries pooled. Results are reported in aggregate across three procedures with meaningfully different mechanisms and nutrient absorption profiles.
• Zero pregnancies. The stated outcome is male infertility. Twelve months of follow-up produced no conceptions, which the paper buries in a single sentence. This is the most important result and receives the least discussion.
• Surrogate endpoints only. Testosterone and sperm motility improved; whether this translated to reproductive success is unknown and unasked.
• Funding not disclosed. No funder listed for a prospective surgical study with 43 enrolled patients is unusual.
• Full-text contamination. The full text contains large verbatim sections from a separate 2018 systematic review. This raises concerns about how this paper was assembled and reviewed.
• Small N. 43 participants across three surgical groups leaves individual procedure subgroups too small to support any procedure-level conclusions.
• Conclusion overreach. Calling MBS "an effective therapeutic strategy for obesity-related male infertility" on the basis of a 43-person case series with no pregnancies is not warranted by the data.

Strengths

• Prospective design with pre- and post-operative measurements at three timepoints
• Comprehensive hormonal panel: FSH, LH, testosterone, estradiol, prolactin
• Semen analysis conducted using standardized WHO parameters
• 12-month follow-up — longer than many similar studies
• Ethical approval obtained from Cairo University Research Ethics Committee; all participants consented
• No competing interests declared

Verdict

The hormonal and semen data here are internally consistent with the broader literature showing that obesity-related hypogonadism and sperm dysfunction partially reverse with significant weight loss. But this paper cannot tell you whether bariatric surgery is superior to dietary weight loss, which of the three procedures works best, or — most critically — whether these laboratory improvements translate into actual pregnancies. The zero-pregnancy finding in 43 men over 12 months is conspicuous and should be the headline of the discussion, not a footnote. The apparent contamination of the full text with passages from a 2018 systematic review is a separate problem that warrants verification. Worth reading alongside the cited literature on bariatric surgery and male fertility; not a standalone basis for any clinical conclusion.