<qa>  What is the most common surgical procedure in urologic practice?Open nephrectomy is one of the most common surgical procedures in urologic practice. Pain after surgery remains a significant clinical problem as it impairs recovery adversely and may lead to the transition to chronic pain. The open approach represents a major physical trauma including postoperative pain and discomfort in the convalescence period. Adequate control of postoperative pain facilitates earlier mobilization and rehabilitation. Patient-controlled analgesia PCA is effective to treat pain at rest, but seems to be inadequate for dynamic analgesia and may also elicit side effects that may delay hospital discharge. Preventing early and late postsurgical pain is an important challenge for anesthesiologists and surgeons. 