Isolated teratozoospermia: revisiting its relevance in male infertility: a narrative review.

Contributors: Dr. Marlon Martinez (Philippines), Dr. Chu Ann Chai,

(Malaysia), and Prof. Christopher Ho (Malaysia)

Commentary:

Semen analysis, despite its flaws and shortcomings, is still considered the cornerstone in the initial evaluation of men with poor productive potential. Sperm morphology remains an essential component of this examination. Any value below the lower reference limit set by the most recent sixth edition of the World Health Organization (WHO) is termed teratozoospermia. Based on available data, there is conflicting evidence on the influence of isolated teratozoospermia on reproductive outcomes and no consensus on its management.

In this current manuscript, the authors performed a comprehensive literature search from the database on PubMed regarding the impact of isolated teratozoospermia on male reproductive potential. A total of 81 original articles and 7 systematic reviews and meta-analyses were included in forming this narrative review. Atmoko et. al. concluded that future studies should be conducted to arrive at definitive recommendations on the assessment and treatment of men with isolated teratozoospermia.

Kruger et. al., as early as 1986, established a reliable and reproducible classification of sperm morphology that was used as an indicator for assisted reproductive technology (ART). Based on the classification, teratozoospermia has been associated with poor fertilization and pregnancy outcomes after ART. Significant changes in the classification had been observed including the continued lowering of the threshold value. Although the criteria are more precise and descriptive, not all are controversial. There is an inherent variability and subjectivity in intra and inter laboratory assessment of sperm morphology, underscoring the complexity of fertility assessment. Hence, standard ization, quality control, and training of personnel should be given priority to improve evaluation.

There is no available guideline for the management of isolated teratozoospermia as most of the studies did not address this condition. In addition, there is limited data on the effective therapeutic options for isolated teratozoospermia. There are conflicting reports on the prognostic value of sperm morphology on natural conception, intrauterine insemination (IUI), in vitro fertilization (IVF), and intracytoplasmic injection (ICSI).

Traditionally, couples are counseled to undergo IVF/ICSI once diagnosed with such sperm abnormality. Couples with isolated teratozoospermia should be advised to undergo a trial of natural conception or IUI before proceeding with IVF/ICSI. This is a more cost-effective viable option for these infertile couples. From a personal standpoint, these treatment options can be offered in men with normal other semen parameters and the absence of pathologic female factors. The absence of complete globozoospermia and primary ciliary dyskinesia allows couples a trial of natural conception. There are some reports that reproductive outcomes are similar in men with isolated teratozoospermia, even in extremely low sperm morphology, compared to men with normal morphology who underwent IUI. There is no clear consensus in the literature on whether ART improves the outcome in men with isolated teratozoospermia as pieces

of evidence showed contradictory results.

Management of isolated teratozoospermia should directly treat the etiology. Infertile men should be treated based on their overall clinical scenario including female factors. These include lifestyle modification, avoidance of occupational hazard exposure, and varicocelectomy. While medical therapies such as antioxidants show promise in certain cases, more research is needed to validate their efficacy and inform clinical practice. The predictive value of isolated teratozoospermia on reproductive outcomes is still a matter of debate. This can be due to its association with sperm DNA fragmentation and reactive oxygen species leading to oxidative stress. The SWOT analysis highlighted recommendations on the strength of the more well-defined sperm morphology in the sixth WHO laboratory manual of semen examination, and the limitation of the lack of evidence on the treatment of isolated teratozoospermia, warranting further research to provide a stronger evidence base.



In summary, Atmoko et al offer a thorough examination of isolated teratozoospermia from a molecular, morphology, and clinical aspect, at the same time highlighting its implication for male infertility diagnosis and treatment. This underscores the scarcity of the currently available evidence and emphasizes the need for further studies to strengthen recommendations.

Take Home Message: Contributing author - Ashok Agarwal

Isolated teratozoospermia, characterized by abnormal sperm morphology with normal counts and motility, has conflicting consequences for male infertility. While it is linked to DNA damage and oxidative stress, its impact on fertility outcomes and assisted 

reproductive technology remains unclear. Further research is essential to clarify its clinical significance and treatment options.