Dados do Trabalho

Title

Sperm capacitation by swim-up, are we really selecting the best spermatozoa?

Objective

In infertile couples, sperm capacitation is used as a complement to the spermogram evaluation and especially in seminal samples that will be submitted to In-Vitro Fertilization (IVF). Despite the effectiveness related to the selection of motile spermatozoa, there are few studies in the literature that demonstrate the impact of swim-up on the improvement of morphology. This fact impairs the evaluation of the real efficiency of this method, which can result in samples with good motility, but of low quality, since, although mobile, these cells can present important morphological alterations, capable of negatively influencing IVF success rates.
For this reason, the aim of this study was to evaluate the impact of sperm capacitation (swim-up) on the seminal parameters of samples of infertile couples with teratozoospermia, through pre and post swim-up analysis.

Methods

A prospective cohort study was performed that included 71 seminal samples from infertile couples with the following criteria: age > 18 years, presence of teratozoospermia (Kruger <4%), sperm concentration > 5 x 106/ml and vitality > 58%. The study was approved by the Research Ethics Committee under CAAE 39759020.1.0000.0018. Patients who met the inclusion criteria underwent seminal collection and evaluation of seminal characteristics shortly after liquefaction. Subsequently, seminal processing (swim-up) and a new reassessment of concentration, motility and morphology were performed. Categorical variables were compared with Chi-square, continuous using t-tests and associations through logistic regression. Differences between groups were considered significant when p<0.05.

Results

Mean age was 37.4 years (± 6.4) and abstinence time was 5.5 days (± 0.9). The analysis after swim-up showed that despite the reduction in total sperm concentration (74.5 x 106 versus 27.8 x 106 per ml, p < 0.001), there was progressive motility increase (46.2% versus 94.8%, p < 0.001). There was a small increase in the mean percentage in the rate of normal spermatozoa (1.4% versus 2.2%, p < 0.001), despite this, morphology indices still remained abnormal in 86% of patients (below 4%).

Conclusion

We observed a slight increase in the rate of morphologically normal spermatozoa after sperm capacitation, however, there was no normalization of the morphology index after the swim-up - which remained below 4% in 86% of individuals suggesting that there is little benefit of the method in morphological selection. Thus, the increase in the percentage of progressive motile spermatozoa does not translate into a significant gain in the quality of the samples, because the morphological abnormality was maintained in most patients and it is known that abnormal morphology is associated with worse embryonic development and worse results in IVF.

Keywords

Infertility; Spermogram; swim up; Teratozoospermia; Semen;