Linear and non-linear relationships between the 'swelling test' and conventional semen variables in men suspected of primary infertility

Assessment of sperm functional competence and sperm-egg interaction

A precise understanding in the functional competence of mammalian sperm is essential to generate clinical advances for the treatment of infertility and novel contraceptive strategies. The fundamental knowledge on the controlling parameters for spermatozoal activation process will help in the identifying the causes in fertilization failure due to male factor as well as in developing male contraceptive methodologies. The defects in the sperm-egg interaction seem to be one of the controlling mechanisms, however, none of the presently available methods for the evaluation of the fertilizing ability of sperm precisely indicates the reason for the failure or the success of sperm entry into egg. Adequate number of motile spermatozoa with normal morphology and timely occurrence of acrosome reaction are presumably the major prerequisites for the penetration through the egg investments. The present communication briefly reviews some of the main features of mammalian sperm which control the success or the failure of fertilization and existing clinical methods indicating the lack of fundamental knowledge on the sub-cellular and molecular aspects of this unique and species-specific cell-cell interaction.

Hypo-osmotic swelling test: a reliable screening assay for routine semen specimen quality screening

We investigated whether the hypo-osmotic swelling (HOS) test is a reliable screening method for routine semen specimen quality screening. Of 159 male patients, 171 semen samples were investigated using the HOS test as well as routine semen specimen screening used in our clinic. There was a significant correlation between the HOS test and most semen parameters. There was no significant correlation between the HOS test and the percentage of morphologically normal spermatozoa in the initial semen sample. The HOS test is a reliable screening method for routine semen quality screening.

Evaluation of the hypo-osmotic swelling test in relation with advanced methods of semen analysis

The hypo-osmotic swelling test was claimed to assess an independent functional characteristic of human spermatozoa bearing relevance to their fertilizing capacity. To test this claim, we have studied the relationship between the result of the hypo-osmotic swelling test with that of conventional semen analysis and sperm motility patterns, the semen content of adenosine triphosphate, the staining pattern to acidified aniline blue, and the zona-free hamster oocyte test. The result of the HOS test is significantly correlated with all sperm characteristics except for the aniline blue stainability and the hamster oocyte test. The capacity of spermatozoa to react in a hypo-osmotic environment expresses the same functional information as the viability test using eosine staining. It is concluded that the hypo-osmotic swelling test does not add relevant information to that obtained by routine sperm analysis with regards to the fertilizing potential of semen.

The predictive fertilization value of the hypoosmotic swelling test (HOST) for fresh and cryopreserved sperm

BACKGROUND

The hypoosmotic swelling test (HOST) was recommended as a predictive test for in vitro fertilization (IVF) outcome. These results, however, were controversial and the results for thawed semen were insufficient. The present study was conducted in order to clarify the predictive value of the HOST for IVF in fresh and thawed sperm.

METHODS

The hypoosmotic swelling test was performed in three groups: husband's fresh semen "subfertile" group, donor's thawed semen group, and donor's fresh semen "fertile" group.

RESULTS

No correlation was found between HOST values and sperm characteristics in fresh or thawed sperm. Fresh sperm HOST values correlated with IVF fertilizations. No such correlations were found when thawed sperm was used. HOST values were significantly higher in the fresh fertile donor group than in the fresh subfertile group (P less than 0.001). Following the freezing and thawing process, HOST values decreased dramatically. Nevertheless, the fertilization rate was still higher compared to that of the fresh subfertile group (P less than 0.001). There were significantly more IVF cycles with no fertilizations when HOST values were below 45%.

CONCLUSION

The HOST has a predictive value for fertilization of oocytes in IVF cycles when fresh semen, but not thawed sperm, is used. The freezing-thawing process affects the outer membrane of the spermatozoon and changes its characteristics, leading to a decrease in HOST values. Sperm characteristics that play a role in the fertilization process are not expressed directly by HOST values.