Preoperative cesarean delivery intravenous acetaminophen treatment for postoperative pain control: a randomized double-blinded placebo control trial

Background: The United States currently has an opioid use disorder epidemic and research evaluating ways to minimize the use of opioids postsurgery are needed. One of these options is intravenous acetaminophen. If the use of preoperative intravenous acetaminophen was found to be effective for cesarean delivery, this would be beneficial for both the mother and breast-feeding neonate.

Objective: The primary study objective was to see if maternal opioid use was significantly less in the postoperative period for the study group that received 1 g of intravenous acetaminophen preoperatively compared with a control group that received placebo. The secondary objectives were to evaluate maternal length of stay and pain scores postoperatively, and assess the acetaminophen level in cord blood at delivery.

Study design: This study was a prospective double-blinded randomized placebo-controlled trial. All pregnant patients who entered labor and delivery for a scheduled cesarean from November 2015 through April 2017 were eligible. Once consented, the medication was supplied by the pharmacy department, which performed the blinded randomization. Both the study drug of 1000 mg (1 g) of acetaminophen and placebo of normal saline were distributed as unmarked 100-mL bags administered over 15 minutes just prior to incision. No study personnel from the obstetric or anesthesia departments had any access to the randomization. Based on a power analysis using the published surgical data results, the goal was to obtain a minimum of 100 patients (50 patients in each arm). Primary data collection included demographics, number of opioid doses and morphine milligram equivalents administered to the patient postoperatively, length of stay postdelivery, pain scores, and newborn cord blood acetaminophen levels. Exclusions were maternal acetaminophen allergy, receipt of acetaminophen in the prior 24 hours, opioid use disorder, and hepatitis/liver impairment. Statistics involved χ², Fisher exact, and the Student t test where appropriate and a P value <.05 was considered significant with all tests considered against a 2-sided alternative hypothesis.

Results: A total of 105 patients were evaluated with 51 who received intravenous acetaminophen and 54 who received placebo. The number of postoperative opioid medication doses administered to the study group was 11.1 (±8.9) compared with the number received by the control group of 10.5 (±8.5), P = .72. The morphine milligram equivalents in the study group was 94.2 (±40.4) compared with the control group of 90.7 (±42.1), P = .67. The length of stay and pain scores were not different between the groups. All of the umbilical cord blood values for acetaminophen were subtherapeutic.

Conclusion: These data demonstrate that for cesarean delivery, the use of a preoperative 1-g intravenous dose of acetaminophen does not decrease the number of opioid medication doses or the morphine milligram equivalents administered postoperatively, nor does it decrease length of stay postcesarean. The administration of 1-g intravenous acetaminophen preoperatively does not result in elevated newborn cord blood levels (ClinicalTrials.govNCT02694653).