Enlarged spectrum of seminological diagnoses using the resazurin colour reaction; a spectrophotometric application

Two sets of investigations were carried out in the present study to establish whether, in semen samples processed for the resazurin reaction (RT), the colour change and its intensity were informative for both the quality and quantity of spermatozoa. First, the results of RT were read visually using single semen samples from 42 consecutive men from infertile couples. In the second step, the results were additionally read using a spectrophotometer. Single semen samples obtained from another 87 consecutive men from infertile couples and 12 men from fertile couples were analysed in this step. Visual analysis, which involved grading against and RT colour chart, revealed a significant positive correlation between the RT results and the quantity and quality of spermatozoa. Azoospermia was diagnosed by grade number 1 (dark purple colour), while the highest grades 8-11 (colours dark red to pink) represented a homogeneous group of patients with the highest quality of spermatozoa (> 60% motility) and quantity (> 60 x 10(6)/ml ejaculate). Normal parameters of spermatozoa, according to WHO, appeared with a high predominance (89-100% of cases) in this group and were present in most of the samples. Thus, the grades 8-11 might represent semen samples with optimal fertility potential. Spectrophotometric analysis of RT revealed that visual characteristics corresponded closely to the values for optical density (OD) of the samples. The OD for normozoospermic samples ranged between 1.48 and 1.84; for oligozoospermia between 1.2 and 1.48; for azoospermia between 0.98 and 1.1. The OD for samples with putative optimal fertility potential ranged between 1.6 and 1.84. RT evaluation using a spectrophotometer may therefore provide a tool for obtaining a wider spectrum of seminological diagnoses than classic microscopic examination, especially for distinguishing men with probable optimal fertility potential.