Department of Biological Sciences, College of Medicine and Life Sciences, University of Toledo, Toledo, OH, 43607, USA.
Department of Urology, College of Medicine and Life Sciences, University of Toledo, Toledo, OH, 43607, USA.
J Assist Reprod Genet. 2021 Feb;38(2):265-276. doi: 10.1007/s10815-020-02037-5. Epub 2021 Jan 2.
Semen analysis is the cornerstone of evaluating male infertility, but it is imperfect and insufficient to diagnose male infertility. As a result, about 20% of infertile males have undetermined infertility, a term encompassing male infertility with an unknown underlying cause. Undetermined male infertility includes two categories: (i) idiopathic male infertility-infertile males with abnormal semen analyses with an unknown cause for that abnormality and (ii) unexplained male infertility-males with "normal" semen analyses who are unable to impregnate due to unknown causes. The treatment of males with undetermined infertility is limited due to a lack of understanding the frequency of general sperm defects (e.g., number, motility, shape, viability). Furthermore, there is a lack of trusted, quantitative, and predictive diagnostic tests that look inside the sperm to quantify defects such as DNA damage, RNA abnormalities, centriole dysfunction, or reactive oxygen species to discover the underlying cause. To better treat undetermined male infertility, further research is needed on the frequency of sperm defects and reliable diagnostic tools that assess intracellular sperm components must be developed. The purpose of this review is to uniquely create a paradigm of thought regarding categories of male infertility based on intracellular and extracellular features of semen and sperm, explore the prevalence of the various categories of male factor infertility, call attention to the lack of standardization and universal application of advanced sperm testing techniques beyond semen analysis, and clarify the limitations of standard semen analysis. We also call attention to the variability in definitions and consider the benefits towards undetermined male infertility if these gaps in research are filled.
精液分析是评估男性不育症的基石，但它并不完善，不足以诊断男性不育症。因此，大约 20%的不育男性存在不明原因的不育，这一术语涵盖了原因不明的男性不育。不明原因的男性不育包括两类：（i）特发性男性不育——精液分析异常的不育男性，其异常原因不明；（ii）原因不明的男性不育——精液分析“正常”但由于未知原因无法使女性受孕的男性。由于对一般精子缺陷（例如数量、活力、形态、活力）的频率缺乏了解，因此无法对不明原因不育的男性进行治疗。此外，缺乏可靠、定量和预测性的诊断测试来检查精子内部的缺陷，例如 DNA 损伤、RNA 异常、中心粒功能障碍或活性氧，以发现根本原因。为了更好地治疗不明原因的男性不育症，需要进一步研究精子缺陷的频率，并开发出能够评估精子内部成分的可靠诊断工具。本综述的目的是基于精液和精子的细胞内和细胞外特征，独特地创建一个关于男性不育症分类的思维模式，探讨各种男性因素不育症的流行情况，提请注意除精液分析之外，先进的精子检测技术缺乏标准化和普遍应用，并阐明标准精液分析的局限性。我们还提请注意定义的可变性，并考虑如果填补这些研究空白，对不明原因的男性不育症的益处。
