Surgical abortion is a common and safe procedure, yet many patients experience significant pain and anxiety despite the routine use of moderate sedation. Standard sedation regimens typically rely on opioids and benzodiazepines. However, institutional policies, safety limits, and provider preference can restrict dosing, leaving some patients with inadequate pain control during a physically and emotionally vulnerable experience.

This randomized, double-blind, controlled trial will evaluate whether intravenous diphenhydramine, used as an adjunct to standard moderate sedation, improves patient-reported pain during first-trimester surgical abortion. Adult patients undergoing uterine aspiration with moderate sedation at the University of Rochester’s Complex Family Planning Clinic will be randomized to receive either diphenhydramine or placebo (normal saline) in addition to standard care. The primary outcome will be participant-reported pain intensity during uterine aspiration, measured using a visual analog scale. Secondary outcomes will include pain at multiple procedural time points, provider-assessed depth of sedation, total sedative medication use, time to discharge, and the incidence of adverse events.

By centering patient-reported outcomes and evaluating a low-cost, widely available medication, this study aims to generate practical, abortion-specific evidence that can be easily translated into clinical practice. Findings have the potential to inform sedation protocols, reduce unwarranted variability in pain management, and improve the procedural experience for patients. Ultimately, this project seeks to support more equitable, patient-centered approaches to pain management in abortion care.