Purpose To assess if the choice of acetaminophen formulation (intravenous vs oral) when administered preoperatively for ambulatory cystoscopy procedures is associated with differences in anesthetic outcomes. Methods Medical records of adult patients undergoing ambulatory cystoscopy procedures at an outpatient procedural center from July 1, 2014, through November 30, 2017, were abstracted. The association between anesthetic outcomes (severe pain, rescue opioids, postoperative nausea, and vomiting) and acetaminophen formulation was assessed. Propensity-adjusted analyses were performed using inverse probability of treatment weighting to account for potential confounders. Results During the study time frame, there were 611 intravenous and 2955 oral acetaminophen administrations for cystoscopy procedures. Postoperative bladder spasms were a major contributor to severe pain and complicated 1036 cases, with similar rates between intravenous (N = 183, 29.9%) and oral (N = 853, 28.9%) formulations, P = .625. After adjusting for bladder spasms, intravenous acetaminophen was associated with longer anesthesia recovery (estimate 5.2 [95% CI 0.5-9.9] minutes, P = .030), use of rescue opioids (odds ratio 1.33 [1.07-1.66], P = .012), and postoperative nausea and vomiting (1.40 [1.02-1.93], P = .037), but not severe pain (1.07 [0.81-1.40], P = .640). Conclusion Preoperative intravenous acetaminophen compared to oral acetaminophen for ambulatory cystoscopy procedures was not associated with better anesthetic outcomes. Bladder spasms were a major contributor to postoperative pain.
