Intraoperative and postoperative analgesic efficacy and adverse effects of intrathecal opioids in patients undergoing cesarean section with spinal anesthesia: a qualitative and quantitative systematic review of randomized controlled trials.

SPINAL anesthesia is commonly used for cesarean section, and it has become a popular practice to add opioids to spinal solutions to enhance and prolong intraoperative and postoperative analgesia. Morphine and fentanyl are the opioids most often used for this purpose, but there is not a general consensus about the benefits of the various regimens, and the incidence of side effects with different opioids and doses is controversial. Recently, a number of systematic reviews have been published in the field of pain and perioperative medicine. The aim of a systematic review is to summarize available information from controlled clinical trials to produce evidence-based estimates of the true clinical effect of an intervention. The purpose of this systematic review was to investigate the effect of intrathecal opioids added to spinal anesthesia on intraoperative and postoperative pain and to evaluate adverse effects in patients scheduled for cesarean section, using evidence from all relevant randomized controlled and blinded trials.