P-062 The impact of isolated teratozoospermia on cumulative live birth rates in IVF and ICSI treatment: a retrospective analysis of 5254 completed cycles
Authors: Zhang X , McAuliffe D , Ugne G , Donnelly L , De Dios Sanz Y , Kovacs A , Garcia Aroz V , Florio D , Kennedy A , Walsh M , Lopez P , Lawson C , Culligan J , O’Boyle S , Waterstone J 
Published: July 2024

Study question

To assess fecundity using cumulative live birth rate (CLBR) per egg collection to determine if IVF and ICSI outcomes are significantly influenced by sperm morphology.

Summary answer

The presence of isolated teratozoospermia does not have a significant impact on the CLBR of IVF treatment.

What is known already

There is ongoing debate regarding the clinical significance. Some studies indicate a pivotal role of sperm morphology in successful pregnancies, others cast doubt on its reliability as a predictive factor. Despite the application of stringent grading criteria, concerns remain about the subjective nature of assessing sperm morphology. Discrepancies in success rates between normozoospermic and isolated teratozoospermic groups shown by previous research findings underscore the uncertainty surrounding this matter. Inconsistent findings in previous research may be explained by limited sample sizes and a focus on immediate successes, neglecting subsequent frozen cycles. This study seeks to address the overlooked aspects of teratozoospermia.

Study design, size, duration

A retrospective study was conducted at Waterstone Clinic, involving 5254 IVF/ICSI autologous cycles completed between 2009-2022 cycles (completed meaning all embryos were either transferred or disposed of). Cycles were categorised according to sperm morphology and divided into two groups: the isolated teratospermic (ITS) group (1218 cycles) defined as having less than 4% normal morphologic forms with all other semen parameters being normal, and the normal sperm (NS) group (4036 cycles).

Participants/materials, setting, methods

The primary outcome measures, included fertilisation rate, number of cryopreserved embryos per egg collection, and CLBR. Employing multivariate statistics, the analysis explored the impact of interferons on CLBR in relation to variables such as sperm morphology, female age, egg number, and aetiology.

Main results and the role of chance

The female base characteristics were similar between the two groups in terms of age (37.1 vs 37.1 y/o), oocyte number (9.4 vs. 9.7) and FSH level (7.6 vs. 7.6 IU/L). Statistically significant differences were observed in fertilisation rates (61.7% vs. 65.8%, p &lt; 0.001) and fertilisation failure (5.9% vs. 3.3%, p &lt; 0.001) from IVF treatments when comparing the ITS and the NS groups. However, there was not any significant difference in the number of cryopreserved embryos between the two groups. Additionally, the CLBR did not show any significant difference between the two groups for IVF (35.8% vs. 37.8%, p &gt; 0.05) or ICSI treatments (38.1% vs. 33.2%, p &gt; 0.05). ICSI did not confer any benefit in improving the CLBR outcome when compared to conventional IVF, when adjusted for female age, number of oocytes collected, and aetiology.

Limitations, reasons for caution

While this study is retrospective it encompasses a substantial cohort. A potential for bias due to the selection criteria for IVF and ICSI exists. The intrinsic subjectivity in sperm morphology assessment introduces additional potential bias.

Wider implications of the findings

Despite the lack of support from CLBR to advocate for choosing ICSI in patients with ITS, this study suggests that couples with ITS experience lower fertilisation and higher fertilisation failure rates with IVF. This observation can serve as a valuable indicator for investigating the occurrence of fertilisation failure.

Trial registration number

not applicable