When the vas deferens is blocked, sperm is unable to be transported into the urethra making it impossible to conceive.The procedure is an alternative to the expensive MESA procedure and bypasses MESAs technical difficulties too. In PESA, a small needle is inserted through the skin of the scrotum to collect sperm from the epididymis. This procedure is not very time consuming and rarely needs hospitalisation and the extracted sperm is used for IVF or ICSI procedures but even if it is cheaper than MESA, it is less effective being a blind procedure and does not use a guided microscope. Many a times a supportive second procedure has to be performed to save an IVF cycle in cases where PESA has not yielded satisfactory results. However, an advantage of the procedure is that it can be repeated if necessary without the need of an anesthesia or any other surgical intervention.