Effect of TAP Block on Stress Hormones

Random allocation of patients in two groups; Tap block group (T group) and control group (C group). All patients will receive standard general anesthesia and postoperative pain management. The TAP group patient will receive ultrasound guided (US) TAP block with 20 cc of 0.25% of bupivacaine and control group will receive 20cc of normal saline. TAP block in both groups will be performed with US guidance and the study drug will be injected after complete visualization of the needle tip between the internal oblique and the transversus abdominis muscles. Venous blood samples (5 ml for each time) for metabolic and stress hormones, including, Serum cortisol and nor-epinephrine will be collected before anesthesia at the time of cannulation (T1),60 minutes after incision(T2), 6hrs (T3)and 12 h (T4) after the surgery. Postoperatively patient will be put on patient controlled intravenous infusion of nalbuphine