Microsurgical epididymal sperm aspiration (MESA) is a minimally invasive surgical procedure performed to retrieve sperm from the epididymis in men with obstructive azoospermia. This technique involves the use of an operating microscope to locate and aspirate sperm directly from the epididymal tubules, which can then be used for assisted reproductive techniques such as in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI).