Is ABO Blood Group a Predictive Factor for the Amount of Opioid Consumption in the First 24 Hours After Cesarean Section?

BACKGROUND: Cesarean section is the most common major surgery performed globally. Blood group O has been found as a factor affecting pain severity after cesarean section. We aimed to evaluate the predictive factors, including ABO blood group, for the amount of opioid consumption (measured as milligrams of morphine equivalent [MME]) within the first 24 hrs after cesarean section. METHODS: This retrospective study was done in 1530 pregnant women who had a cesarean section under the same regimen of spinal anesthesia (2.2 mL of 0.5% hyperbaric bupivacaine and morphine 0.2 mg). All were prescribed regular paracetamol and ibuprofen for postoperative pain control. Univariate and multinomial regression analyses were performed to identify the predictive factors for opioid consumption in the first 24 hrs postoperatively. RESULTS: About 2/5 of them (43.3%) received 0 mg MME, while 25.6%, 23.7% and 7.4% received 1–5, 6–10 and >10 mg MME, respectively. The majority have blood group O (40.6%), while 23.4%, 28% and 8% have blood group A, B and AB, respectively. After univariate and multinomial regression analyses, operation time, opioid consumption in PACU, maximum VNRS within the first 24 hrs and consumption of both paracetamol and ibuprofen were identified as predictive factors for postoperative opioid consumption. ABO blood group exhibited no correlation for opioid requirement postoperatively. CONCLUSION: ABO blood group is not a predictive factor for opioid requirement within the first 24 hrs following cesarean section. Duration of operation, opioid given in PACU, maximum VNRS on ward and consumption of both paracetamol and ibuprofen have been found to be predictive factors for postcesarean opioid requirement.