Background and purpose: Uncontrolled postoperative pain after caesarean section leads to increased complications and mortality rates. This study aimed to compare the effects of intraperitoneal administration of bupivacaine, morphine, and dexamethasone on pain after caesarean section.

Materials and methods: This interventional, double-blind study was conducted in 144 pregnant women aged 20-45 years, undergoing elective caesarean section. The participants were randomly selected and divided into four groups (n=36). All patients underwent general anesthesia. During the last stage of surgery, 30 cc of bupivacaine 0.25%, 16 mg of dexamethasone (diluted to 30 cc), 5 mg of morphine (diluted to 30 cc), and 30 cc of saline were intraperitoneally administered by a surgeon in groups one (B), two (D), three (M), and control (S), respectively. Postoperative pain scores (within the range of 0-10) in the participants were recorded at two, four, and six hours after surgery using visual analog scale (VAS). Moreover, the number of analgesic medications, vital signs, and incidence of nausea and vomiting were recorded. The patients with VAS scores higher than three were administered with intravenous meperidine. Data analysis was performed in SPSS, version 23, using ANOVA test. All P-values less than 0.05 were considered statistically significant.

Results: Significant differences were observed between the control group and other groups in VAS score and mean consumption of meperidine in recovery, and at two, four, and six hours after the surgery (P<0.001). At four and six hours after the surgery the participants in the dexamethasone (0.75±0.21, 0.52±0.12) and bupivacaine (0.86±0.35, 0.83±0.28) groups experienced the lowest level of pain, compared to the other groups.

Conclusion: This study showed that intraperitoneal administration of intraperitoneal administration of bupivacaine, morphine, and dexamethasone significantly reduced postoperative pain during the first six hours after caesarean section.