Cryptorchidism and Infertility: What Do We Know So Far?

A review maps the biological pathways from undescended testes to infertility — temperature, hormones, oxidative stress, and autoimmunity

Journal: Asian Journal of Andrology | Published: 2026-01-09 | Type: Review | PMID: 41504580 Authors: Liu Yu-Xin, Zhang Hai-Yang (Department of Urology, Shandong Provincial Hospital, Shandong University, Jinan, China) Funding/COI: Not disclosed

Summary

This narrative review from a Chinese urology department catalogs the mechanisms linking cryptorchidism to male infertility. The authors cover five overlapping pathways: thermal/pressure damage to spermatogenic and Sertoli cells, hypothalamic-pituitary-gonadal (HPG) axis disruption, oxidative stress-driven sperm DNA damage, nerve-mediated contralateral testicular injury, and antisperm antibody-driven autoimmune damage. No new data are generated — this is a synthesis of existing mechanistic literature. The clinical takeaway is implicit: the earlier and more completely the condition is addressed, the more of these pathways can be interrupted.

Claims

• Failure of testicular descent elevates local temperature and pressure, increasing apoptosis of spermatogenic and Sertoli cells
• Cryptorchidism disrupts HPG axis signaling, reducing intratesticular testosterone and producing abnormal FSH and LH secretion
• Oxidative stress in undescended testes causes sperm DNA damage and plasma membrane impairment, interfering with sperm-oocyte fusion
• Unilateral cryptorchidism can injure the ipsilateral genitofemoral nerve, with downstream effects on the contralateral testis via oxidative stress and apoptosis — meaning a one-sided problem can damage both testes
• Antisperm antibody production triggers autoimmune responses that may destroy germ cells
• Damage to type A dark (Ad) spermatogonia — the stem cell reservoir — is described as a high-risk factor for permanent infertility

Study Quality

This is a narrative review, not a systematic review or meta-analysis. There is no PRISMA methodology, no stated search strategy, no inclusion/exclusion criteria, and no synthesis of effect sizes. The abstract does not specify how many studies were included or what time range was covered. As a synthesis of mechanistic biology rather than clinical outcomes, it is not directly answerable by RCT-level evidence — much of the underlying science comes from animal models and small human histological studies, a limitation the abstract does not acknowledge.

The two authors share the same single institution, which limits the breadth of perspective. No funding or conflicts of interest are declared — an omission that is increasingly flagged by journals as a transparency failure, even for review articles.

Red Flags

• Narrative review with no disclosed methodology — cherry-picking risk is non-trivial
• No funding or COI disclosure for either author
• Mechanism-focused: does not report clinical outcome data (fertility rates, sperm parameters post-treatment) that would be more actionable
• Much of the mechanistic evidence cited in this field derives from animal models; the abstract does not distinguish these from human data
• The contralateral testis injury claim via genitofemoral nerve damage is a less-established pathway — the abstract presents it without qualification of the evidence quality behind it
• No quantitative data in the abstract: no effect sizes, no prevalence figures, no numbers at all

Strengths

• Covers multiple distinct biological pathways in one place — useful as a conceptual map for clinicians or researchers entering this area
• The Ad spermatogonia point is clinically relevant and often underemphasized in lay coverage of cryptorchidism
• Published in Asian Journal of Andrology, a peer-reviewed journal with reasonable standing in reproductive urology

Verdict

Read this if you need a plain-language overview of why undescended testes damage fertility at the cellular level. Do not cite it as evidence that any specific treatment works, because it reports no clinical outcomes. As a review of mechanisms it is serviceable, but the lack of a systematic methodology, absent disclosure statements, and zero quantitative data in the abstract make it a reference tool, not a landmark paper. It maps the problem without measuring it.