The evolution of testicular sperm extraction and preservation techniques.

Along with the advent of intracytoplasmic sperm injection in 1992, sperm retrieval procedures now allow the possibility of conception from male sterility. In cases of sterility due to blockages in the reproductive tract, sperm retrieval procedures are relatively straightforward and reliable. In nonobstructive azoospermia or testis failure, sperm often can be difficult to retrieve. For this reason, the field of testicular sperm retrieval has witnessed tremendous change and innovation to achieve higher sperm yields, increasing efficiency and safety, along with fewer complications. We review the history and evolution of testicular sperm retrieval since its inception. Using the findings from randomized controlled trials, basic science studies, meta-analyses, case-controlled or cohort studies, best-practice policies, and literature reviews, we outline the concepts, facts, and principles that have been elucidated over several decades of experience with sperm retrieval. We also appraise the merits and issues of the most popular sperm retrieval techniques and strategies. Finally, we define areas of future clinical and laboratory development that will further refine the field of testicular sperm retrieval.