Male reproductive system is like a system of tubes. Sperms are produced in the testis in thin tubes called tubules. These tubules connect to a larger coiled tube known as epididymis. The sperms are stored in epididymis for some time after production. This is connected to the vas deferens and then to the urethra. During ejaculation, the sperm moves through this system of tubes. Due to certain reasons, the semen or the ejaculate lacks the presence of sperm. This condition is called azoospermia which can be obstructive or non-obstructive. Obstructive azoospermia: The sperms are produced in the testis but to a blockage in the epididymis or the vas deferens, they cannot get out. Non-obstructive azoospermia: The sperms are either not produced at all in the testis or are produced in such low levels as to be practically negligible in the ejaculate. Percutaneous Epididymal Sperm Aspiration (PESA) and Testicular Sperm Aspiration (TESA) techniques are used in cases of azoospermia. In PESA, the sperm are extracted from the epididymis and in TESA, the sperm are extracted from of the tubules in the testis. These methods can be used to diagnose the cause of azoospermia and to isolate sperm to be used in assisted reproductive techniques (ART). Who can benefit from the PESA/TESA procedures? The procedures can be used in persons who have: Poor sperm production due to problems in testis. These could be caused by genetic issues, previous infection (e.g. mumps), maldescended testes. An irreversible obstruction of the genital tract caused due to infection, trauma, or surgery Absence of vas deferens from birth (congenital absence) Had a previous vasectomy or an unsuccessful vasectomy reversal How are these procedures done? In PESA, a thin needle is inserted through the skin into the epididymis to obtain sperm. TESA involves passing a needle in the testis and aspirating fluid and tissue (small number of the seminiferous tubules). The sperm is located among the aspirate and tissue in the laboratory. Both these surgical procedures can be performed under local or general anaesthesia. Since the number of sperms recovered from PESA or TESA is very low, these have to be used in combination with intracytoplasmic sperm injection (ICSI). They can rarely be used for intrauterine insemination (IUI). If enough quantity of sperm is retrieved, it can be frozen for future ICSI cycles. Which procedure of the two is better? PESA is generally preferred since the patient can return home within hours and go back to work the next day. With TESA, patients can experience swelling and pain. What is the success rate of the procedures? Both treatments have a success rate of around 25% for every treatment cycle.