Fertilising capacity of human sperms: a simple predictive assay

Male subfertility is a growing reason for assisted reproduction. A limiting factor in male subfertility is asthenospermia. Motility is a cardinal indication of sperm vitality. Thus prognostic assays are aimed at quantitative determination of progression to assess the fertilising potential. However, a method permitting reliable prognosis of the fertilising capacity has yet to be developed. The assay presented here is the outcome of empirical data based on 590 IVF (in vitro fertilisation) trials. It is essentially a further exploitation of the Swim Up procedure, the selected sperms being maintained in culture under identical conditions employed in IVF. Semi-quantitative daily recordings of linear progression until complete extinction provided an index on vitality which is directly related to the fertilising potential. The findings indicated that a threshold of 50% linear motility after 24 hr culture was required to initiate fertilisation. The fertilising potential was guaranteed when at least 60% linear motility was observed at 24 hr, making the assay a predictive one. Its simplicity is an attractive feature.