An examination of predictive markers for successful sperm extraction procedures: a linear model and systematic review

The authors performed a comprehensive review of current literature to create a model comparing commonly evaluated variables in male factor infertility, for example, follicle-stimulating hormone (FSH), testicular volume (TV), and testosterone (T), to better predict sperm retrieval rate (SRR). Twenty-nine studies were included, 9 with data on conventional testicular sperm extraction (cTESE) for a total of 1227 patients and 20 studies including data on microdissection testicular sperm extraction (mTESE) for a total of 4760 patients. A weighted-means value of SRR, FSH, T, and TV was created, and a weighted linear regression was then used to describe associations among SRR, type of procedure, FSH, T, and TV. In this study, weighted-means values demonstrated mTESE to be superior to cTESE with an SRR of 51.9% vs 40.1%. Multiple weighted linear regressions were created to describe associations among SRR, procedure type, FSH, T, and TV. The models showed that for every 1.19 mIU ml^-1 increase in FSH, there would be a significant decrease in SRR by 1.0%. Seeking to create a more clinically relevant model, FSH values were then divided into normal, moderate elevation, and significant elevation categories (FSH <10 mIU ml^-1, 10-19 mIU ml^-1, and >20 mIU ml^-1, respectively). For an index patient undergoing cTESE, the retrieval rates would be 57.1%, 44.3%, and 31.2% for values normal, moderately elevated, and significantly elevated, respectively. In conclusion, in a large meta-analysis, mTESE was shown to be more successful than cTESE for sperm retrievals. FSH has an inverse relationship to SRR in retrieval techniques and can alone be predictive of cTESE SRR.