Predictive value of hypo-osmotic swelling test to identify viable non-motile sperm.

To determine the predictive value of the hypo-osmotic swelling (HOS) test to identify viable, non-motile sperm. Semen samples from 20 men with severe asthenozoospermia underwent traditional seminal analysis, eosin-nigrosin (EN) staining and the HOS test. A further EN stain was then performed on a HOS pre-treated aliquot and a total of 2000 further sperm examined. The median sperm density was 5.1 million/mL (IQR 4.3 approximately 13.1) and the median motility was 3.0% (IQR 0 approximately 7). Seven samples showed complete asthenozoospermia. Initial EN staining showed 59% viability (range 48 approximately 69) despite the poor standard parameters and 47% (range 33 approximately 61) in the complete asthenozoospermia subgroup. The HOS test showed 49.9% reacted overall (range 40 approximately 59) and 41.7% (range 22 approximately 61) in the complete asthenozoospermia subgroup. The combined HOS/EN stain showed the positive predictive value of the HOS test to identify viable sperm was 84.2 % overall and 79.7% in the complete asthenozoospermia subgroup. The HOS test can effectively predict sperm viability in patients with severe and complete asthenozoospermia.