To the Editor:
We appreciate the insightful comments of Dr. Kim (1). As he correctly states, the use of fresh versus cryopreserved sperm has been controversial. While the use of frozen sperm from men with obstructive azoospermia appears to yield equivalent outcomes to fresh sperm, the application to men with nonobstructive azoospermia (NOA) is less certain (2). However, if proven equivalent, Dr. Kim correctly emphasizes the significant logistical and economic burdens that could be improved for couples. Additionally, we agree with his assessment on the importance of methodology. We as male reproductive specialists do not have a standardized, evidence-based protocol for the cryopreservation of sperm. As such, we believe that there should be some caution in mentioning an established detrimental effect of cryopreservation. The analyses that produced such findings suffer the same methodological dependence that is inherent within essentially any cryopreservation data to date (3). Moreover, as data from men with obstructive azoospermia suggest equivalent outcomes, it appears that cryopreservation does not irreparably impact sperm function (2).
Also, Dr. Kim aptly points out the need for more data. While our review provides a comprehensive evaluation of the literature to date on the subject of fresh versus frozen sperm in men with NOA, the number of cycles is limited (4). He mentions the difficulty of randomized controlled trials, which has been experienced by other investigators of the Reproductive Medicine Network when attempting to enroll for a randomized controlled trial on varicocelectomy (5). Indeed, other data sources are needed to improve data on males. Additional male factor data points in the Society for Assisted Reproductive Technology (SART) or the National ART Surveillance System (NASS) may help improve tracking and optimize treatment of severe male factor infertility. We are encouraged as increasing data on the treatment of male factor infertility appears. As Dr. Kim notes, we’re moving in the right direction.
Samuel Ohlander, M.D.
Department of Urology, University of Illinois at Chicago
1. Kim, ED. Commentary on manuscript: “The impact of fresh versus cryopreserved testicular sperm on intracytoplasmic sperm injection (ICSI) pregnancy outcomes in men with azoospermia due to spermatogenic dysfunction: a meta-analysis.” Fertil Steril, in press.
2. Nicopoullos JD, Gilling-Smith C, Almeida PA, Norman-Taylor J, Grace I, and Ramsay JW. Use of surgical sperm retrieval in azoospermic men: a meta-analysis. Fertil Steril 2004;82:691-701.
3. Sperm retrieval for obstructive azoospermia. Fertil Steril, 2008. 90(5 Suppl):S213-8.
4. Ohlander S, Hotaling J, Kirshenbaum E, Niederberger C, and Eisenberg ML. The impact of fresh versus cryopreserved testicular sperm upon intracytoplasmic sperm injection (ICSI) pregnancy outcomes in men with azoospermia due to spermatogenic dysfunction: a meta-analysis. Fertil Steril, 2013.
5. Trussell, JC, Christman GM, Ohl DA, Legro RS, Krawetz SA, Snyder PJ, et al.. Recruitment challenges of a multicenter randomized controlled varicocelectomy trial. Fertil Steril 2011. 96:1299-305.
Published online in Fertility and Sterility doi:10.1016/j.fertnstert.2013.12.017