Diphenhydramine as an Adjunct to Moderate Sedation for Procedural First Trimester Abortions

This single center, double blind, randomized controlled trial will evaluate whether adding intravenous diphenhydramine to a standard moderate sedation regimen improves pain control during first trimester procedural abortion. Participants undergoing uterine aspiration at less than 13 weeks gestation will be randomized 1 to 1 to receive standard moderate sedation with midazolam and fentanyl plus either diphenhydramine 50 mg intravenously or matching placebo. The primary outcome is participant reported pain during uterine aspiration measured by a 100 mm Visual Analog Scale.

Study Overview

• Status: Not yet recruiting
• Conditions: Pain; Anxiety; Abortion
• Intervention / Treatment: Drug: Diphenhydramine; Drug: Placebo

Detailed Description

Surgical abortion is commonly associated with pain and anxiety despite use of local anesthesia and moderate sedation. This study will evaluate the efficacy of intravenous diphenhydramine as an adjunct to a standard moderate sedation regimen for participants undergoing first trimester procedural abortion.

This is a single center, double blind, randomized, placebo controlled trial conducted at the University of Rochester Family Planning Clinic and Strong Memorial Hospital. Participants undergoing first trimester uterine aspiration at less than or equal to 13 weeks gestation will be randomized in a 1 to 1 ratio using a computer generated block randomization scheme to receive either intravenous diphenhydramine 50 mg or matching placebo, in addition to standard moderate sedation with midazolam and fentanyl. Participants, clinical staff, and outcome assessors will remain blinded to treatment assignment.

Pain will be assessed using a 100 mm Visual Analog Scale at baseline, during speculum placement, paracervical block, cervical dilation, uterine aspiration, 10 minutes after the procedure, and 1 hour after the procedure. Sedation depth during uterine aspiration will be assessed using the Modified Observer's Assessment of Alertness Sedation scale. Additional outcomes include total sedative medication dose, time to readiness for discharge, and sedation related adverse events.

• Study Type: Interventional
• Enrollment (Estimated): 98
• Phase: Phase 4

Contacts and Locations

• Study Contact: Name: Sarah Cavegila, MPH; Phone Number: 585-273-5734; Email: Sarah_Caveglia@URMC.Rochester.edu

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Adults age 18 years and older
• Desire procedural abortion with moderate sedation
• Gestational age less than or equal to 13 weeks
• Intrauterine pregnancy or pregnancy of unknown location
• Body mass index less than or equal to 40

Exclusion Criteria:

• Desire medical abortion or desire to continue pregnancy
• Gestational age greater than 13 weeks
• Body mass index greater than 40
• Age younger than 18 years
• Confirmed ectopic pregnancy
• Medical condition that is a contraindication to moderate sedation as determined by the treating clinician

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Supportive Care
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Quadruple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Diphenhydramine plus standard moderate sedation; Participants receive intravenous diphenhydramine 50 mg prior to the procedure, in addition to standard moderate sedation with midazolam and fentanyl. Additional doses of midazolam and fentanyl may be administered during the procedure as clinically indicated.	Drug: Diphenhydramine; Diphenhydramine 50 mg administered intravenously once prior to the procedure.; Other Names: Bendaryl
Placebo Comparator: Placebo plus standard moderate sedation; Participants receive a matching intravenous placebo (normal saline) prior to the procedure, in addition to standard moderate sedation with midazolam and fentanyl. Additional doses of midazolam and fentanyl may be administered during the procedure as clinically indicated.	Drug: Placebo; Matching placebo composed of normal saline administered intravenously once prior to the procedure.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Participant-Reported Pain During Uterine Aspiration	Pain intensity will be measured using a 100 mm Visual Analog Scale (VAS). The VAS ranges from 0 to 100 mm, where 0 represents "no pain" and 100 represents "worst pain imaginable." Higher scores indicate greater pain intensity. This outcome measures the participant's perceived pain during uterine aspiration.	During the procedure, at the time of uterine aspiration

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Sedation Depth During Uterine Aspiration	Sedation depth will be assessed using the Modified Observer's Assessment of Alertness/Sedation (MOAA/S) scale. The MOAA/S scale ranges from 0 to 5, where 5 indicates fully alert and 0 indicates no response to painful stimulus. Lower scores indicate deeper levels of sedation. This outcome measures the level of sedation achieved during uterine aspiration.	During the procedure, at the time of uterine aspiration
Participant-Reported Pain at Speculum Placement	Pain intensity will be measured using a 100 mm Visual Analog Scale (VAS), where 0 represents "no pain" and 100 represents "worst pain imaginable." Higher scores indicate greater pain intensity. This outcome measures pain experienced during speculum placement.	During the procedure, at the time of speculum placement
Participant-Reported Pain at Paracervical Block	Pain intensity will be measured using a 100 mm Visual Analog Scale (VAS), where 0 represents "no pain" and 100 represents "worst pain imaginable." Higher scores indicate greater pain intensity. This outcome measures pain experienced during administration of the paracervical block.	During the procedure, at the time of Paracervical Block
Participant-Reported Pain at Cervical Dilation	Pain intensity will be measured using a 100 mm Visual Analog Scale (VAS), where 0 represents "no pain" and 100 represents "worst pain imaginable." Higher scores indicate greater pain intensity. This outcome measures pain experienced during cervical dilation.	During the procedure, at the time of Cervical Dilation
Participant-Reported Pain 10 Minutes After Procedure Completion	Pain intensity will be measured using a 100 mm Visual Analog Scale (VAS), where 0 represents "no pain" and 100 represents "worst pain imaginable." Higher scores indicate greater pain intensity. This outcome measures post-procedure pain at 10 minutes.	10 minutes after completion of the procedure
Participant-Reported Pain 1 Hour After Procedure Completion	Pain intensity will be measured using a 100 mm Visual Analog Scale (VAS), where 0 represents "no pain" and 100 represents "worst pain imaginable." Higher scores indicate greater pain intensity. This outcome measures post-procedure pain at 1 hour.	1 hour after completion of the procedure
Time to Readiness for Discharge	Time from procedure completion to when the participant meets discharge criteria, measured in minutes. Higher values indicate longer recovery time.	From completion of the procedure until discharge readiness, up to approximately 2 hours
Incidence of Sedation-Related Adverse Events	Number and proportion of participants experiencing sedation-related adverse events, including hypoxia, hypotension, use of reversal agents (naloxone or flumazenil), paradoxical agitation, respiratory depression requiring supplemental oxygen beyond nasal cannula, hypotension requiring vasopressors, or unplanned hospital admission. Higher values indicate greater incidence of adverse events.	From administration of study medication through discharge on the day of procedure

Collaborators and Investigators

• Sponsor: University of Rochester

Study record dates

Study Major Dates

• Study Start (Estimated): May 1, 2026
• Primary Completion (Estimated): February 1, 2027
• Study Completion (Estimated): February 1, 2027

Study Registration Dates

• First Submitted: April 10, 2026
• First Submitted That Met QC Criteria: April 19, 2026
• First Posted (Actual): April 21, 2026

Study Record Updates

• Last Update Posted (Actual): April 21, 2026
• Last Update Submitted That Met QC Criteria: April 19, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Neurologic Manifestations; Mental Disorders; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Pain; Anxiety Disorders; Organic Chemicals; Hydrocarbons; Hydrocarbons, Cyclic; Hydrocarbons, Aromatic; Amines; Benzene Derivatives; Ethylamines; Benzhydryl Compounds; Diphenhydramine
• Other Study ID Numbers: STUDY00011436

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No