Levels of reactive oxygen species before and after sperm preparation: comparison of swim-up and L4 filtration.

In previous studies, high levels of reactive oxygen species (ROS) have been associated with an adverse impact on the fertilizing ability of sperm. The present study evaluated ROS levels in unprocessed (raw) semen specimens and in specimens processed by the traditional swim-up method and by L4 filtration, thereby assessing the potential of these techniques to damage sperm. Semen specimens from 26 men (10 patients in whom subfertility was suspected and 16 donors with normal fertility) were randomly collected, and ROS levels were measured. For all specimens combined (those from patients and those from donors), ROS levels were significantly lower after L4 filtration (6.07 +/- 1.97 mV/s 10(9) sperm-1, p < .01) and after swim-up (5.70 +/- 0.96 mV/s 10(9) sperm-1, p < .001) than in unprocessed ejaculate (12.88 +/- 2.32 mV/s 10(9) sperm-1). However, ROS levels in swim-up and L4 specimens were not statistically different from each other. It would appear that sperm processing by either swim-up or L4 filtration yields specimens with significantly lower levels of ROS than are found in unprocessed ejaculate.