mojtaba ahmadinejad department of surgery, madani hospital, alborz university of medical sciences, karaj, ir iran mozaffar hashemi department of surgery, alzahra university hospital, isfahan university of medical sciences, isfahan, ir iran abbas tabatabai department of surgery, alzahra university hospital, isfahan university of medical sciences, isfahan, ir iran shahram keykha department of emergency medicine, mashhad university of medical sciences, mashhad, ir iran zabihollah taleshi department of emergency medicine, alborz university of medical sciences, karaj, ir iran koorosh ahmadi department of emergency medicine, alborz university of medical sciences, karaj, ir iran; department of emergency medicine, alborz university of medical sciences, karaj, ir iran. tel: +98-9124806577, fax: +98-2634426979