Semen preparation methods and sperm apoptosis: swim-up versus gradient-density centrifugation technique

Objective: To compare the effects of density-gradient centrifugation and swim-up on sperm apoptosis by using a multiparameter flow cytometric method. Design: Autocontrolled split-sample study. Setting: Tertiary infertility center. Patient(s): Sixty-two male partners of couples undergoing infertility investigations. Intervention(S): Each sample was analyzed both before and after semen preparation by optical microscopy and by flow cytometry. Main Outcome Measure(s): Percentage of viable, apoptotic, and necrotic sperm and recovery rate of total motile, progressive motile, and viable sperm before and after the two sperm preparation methods. Result(s): Compared with the original semen, the mean percentages of apoptotic and necrotic sperm were significantly lower after both sperm preparation methods. The mean percentage of viable sperm was significantly higher after swim-up compared with gradient centrifugation. The recovery rates of total motile. progressive motile, and viable sperm were significantly her using gradient centrifugation compared with swim-up. The viable sperm percentage and the progressive sperm motility were significant predictors for negative difference between the two methods in terms of viable sperm percentage after preparation. Conclusion(S): Both sperm preparation methods allow obtaining a sperm population with a low percentage of apoptotic sperm. Therefore, the risk of using apoptotic sperm for clinical treatment seems to be rather low. The choice of method will depend on whether IVF/ICSI or intrauterine insemination is to be performed. (Fertil Steril(R) 2009;91:632-8. (C)2009 by American Society for Reproductive Medicine.)