Randomized controlled trial of intravenous acetaminophen for postcesarean delivery pain control

Cesarean delivery is a common surgery in the United States, with 1.3 million performed during 2009.¹ Obstetricians must balance the growing concern with opioid abuse, dependence, and side effects with optimal postoperative pain control. Intravenous acetaminophen may represent an additional method to decrease the reliance on opioid medications and improve postoperative pain following cesarean delivery.

The objective of the study was to determine whether the administration of intravenous acetaminophen following routine scheduled cesarean delivery would decrease the need for narcotic medications to control postoperative pain.

This was an institutional review board-approved, double-blind, placebo-controlled, randomized trial, registered on clinicaltrials.gov (number 02046382). Women scheduled to undergo cesarean delivery with regional anesthesia at term were recruited. All perioperative and postpartum care was standardized via study order sets. Study patients were given all medications in a standardized manner receiving either acetaminophen 1000 mg intravenously or 100 mL saline (placebo) every 8 hours for 48 hours for a total of 6 doses. The pharmacy prepared intravenous acetaminophen and saline in identical administration bags labeled study drug to ensure blinding. The initial dose of study drug was given within 60 minutes of skin incision. Quantity of breakthrough and scheduled analgesic medications and self-reported pain levels on the Faces Pain Scale (0-10) before and after study drug administration were collected. Patient demographics were extracted from the chart. Power calculation determined that 45 patients per arm were required to detect a 30% reduction in postcesarean narcotic requirement with 80% power and a significance level of P = .05.

A total of 133 patients were consented for the study. Twenty-nine were excluded and 104 patients completed the study: 57 received intravenous acetaminophen and 47 received placebo. There were no differences in baseline demographic characteristics including patient age, body mass index, gravidity, parity, race, comorbidities, or number of prior cesarean deliveries. There were no differences between groups in estimated blood loss or length of stay. The total amount of oral narcotic medications consumed by patients receiving intravenous acetaminophen was significantly reduced when compared with the placebo group (47 mg vs 65 mg of oxycodone; P = .034). The total amount of ibuprofen used between groups was not different. There was no difference in pain scores between groups before and after study dose administration. There was no significant difference in narcotic side effects (nausea/emesis, respiratory depression, constipation) in either study arm.

Intravenous acetaminophen in the postoperative period following cesarean delivery resulted in a significant decrease in oral narcotic consumption for pain control.