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Sperm retrieval rates for microdissection testicular sperm extraction remained constant between 1997 and 2009, except for an increase in SRRs in patients with Sertoli cell only.
Denver-Sperm retrieval rates (SRRs) for microdissection testicular sperm extraction (mTESE) remained constant between 1997 and 2009, except for an increase in SRRs in patients with Sertoli cell only (SCO), according to a large retrospective review.
"Over the three eras evaluated, overall SRR appeared to be relatively constant, at just under 60%. However, there were significant changes in the testicular histology of our population over the same period. Most notably, we saw an increase in the percentage of patients with SCO, from 29% in the early era to 61% in the latest," said Dr. Hsiao, who reported the results at the 2010 American Society for Reproductive Medicine annual meeting in Denver.
Meanwhile, he said, the percentage of patients with hypospermatogenesis on biopsy fell from 26.5% to 15.6%. The rate of patients with maturation arrest remained constant, ranging between 13% and 14.6%.
When researchers stratified patients by histology, those with SCO demonstrated increases in SRR over the three eras, from 35% to 43%, and ultimately 49%. However, this trend did not reach statistical significance, Dr. Hsiao said.
Operator experience linked to success
A lack of statistical significance does not indicate that the relationship is untrue, Dr. Hsiao noted. Moreover, "Our data agree with other research on the learning curve of microdissection TESE that showed increases in SCO sperm retrieval rates with increased operator experience," he said, citing a paper in Fertility and Sterility (2010; 94:1008-11). This study showed a significant learning curve over the first 150 cases, with the most significant SRR improvement seen in patients with SCO on preoperative biopsy, Dr. Hsiao said.
In the Cornell study, SRRs for patients with maturation arrest also remained similar across all three eras.
"SRRs were uniformly good when hypospermatogenesis was seen on biopsy," Dr. Hsiao said. Specifically, these figures hovered between 91.2% and 95.8%. Patients with no available histology also fared similarly across the three eras, he said.
In multivariate analysis controlling for follicle-stimulating hormone (FSH) level, patient age, era of mTESE, and histology on biopsy, only hypospermatogenesis seen on biopsy significantly predicted sperm retrieval, with an odds ratio of 17.6 for sperm retrieval (95% CI: 9.5-32.7), Dr. Hsiao reported.
FSH and testicular volumes have not been shown to be predictive of sperm retrieval in multivariate analysis.
"The only predictor of sperm retrieval found consistently has been the most advanced histology present on biopsy," Dr. Hsiao said.