Adequate pain control is a prerequisite for the use of rehabilitation programs to accelerate recovery from surgery. Postoperative symptoms and complications can be prevented by a suitable choice of anesthetic and analgesic techniques for specific procedures. Thus, combining opioid and/or non-opioid analgesics with regional analgesic techniques not only improves analgesic efficacy but also reduces opioid demand and side-effects such as nausea and vomiting, sedation, and prolongation of postoperative ileus. On other hand, multiple pain assessment instruments or measures exist. However, choosing the correct ageappropriate and suitable instrument is difficult because many patients are non-verbal or are not cognitively aware.