Postoperative analgesia after caesarean section: Intermittent intramuscular versus subcutaneous morphine boluses

SummaryBackgroundSeveral recent studies have demonstrated that the subcutaneous route of morphine administration is effective for the management of postoperative pain. The injection of morphine via an indwelling subcutaneous cannula results in blood concentrations that are comparable to those arising from intramuscular injection. The aim of this study was to compare the analgesic efficacy and adverse effect profile of intermittent intramuscular and subcutaneous morphine boluses after caesarean section.MethodsSixty patients, aged 16–45 years, scheduled for elective caesarean section (CS) were randomly assigned to receive analgesia via either intramuscular (IM group, 0.15 mg/kg) or s.c. injections of morphine (SC group, 0.15 mg/kg). Postoperative pain was assessed at rest and when moving, using a visual analogue scale (VAS) every 4 h. A Mini Mental Status (MMS) examination was used to assess cognitive functions before surgery, at 2 h, 24 h and 48 h after surgery, and at hospital discharge. Side-effects were also recorded systematically during the first 48 h after surgery.ResultsThe SC group showed lower pain scores and higher overall analgesia satisfaction score than the IM group at rest but it was not significant statistically (P > 0.05). During mobilization, the SC group had lower pain scores and it was significant at 12 h, 16 h and 20 h postoperatively (P < 0.05). There was no inter-group difference in postoperative MMS scores. The incidence of side-effects was similar in both groups.ConclusionSC morphine is a satisfactory alternative to IM morphine after CS.