Comparing Pain Improvement for Intravenous Versus Oral Acetaminophen in Acute Pelvic Pain (PIVOTAL)

May 18, 2026 updated by: Montefiore Medical Center

Comparing Pain Improvement for Intravenous Versus Oral Acetaminophen in Acute Pelvic Pain: A Randomized, Double-Blind, Double-Dummy Controlled Trial (PIVOTAL Trial)

The investigator team proposes a randomized, double-blind, double-dummy comparative effectiveness trial conducted in two urban emergency departments (EDs) in the Bronx, New York. This study is designed to determine the relative efficacy of IV acetaminophen compared to PO acetaminophen in treating pelvic pain. This design focuses on the early onset of action and short-term efficacy, which may better capture potential differences between IV and PO acetaminophen in the acute ED setting.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Detailed Description

An estimated 70% of Emergency Department (ED) visits involve pain as a complaint. Although ED practice has shifted away from routine opioid prescribing, uncertainty remains regarding optimal selection among commonly used non-opioid analgesics such as nonsteroidal anti-inflammatory drugs (NSAIDs) and acetaminophen. Medication selection varies by pain etiology, and among patients presenting with musculoskeletal pain, opioids (40.7%), acetaminophen (37.8%), and NSAIDs (22.6%) remain the most frequently administered medications in the ED.

Pain in women has been comparatively understudied. Pelvic pain is common among women of childbearing age, and chronic pelvic pain affects up to 24% of women overall. In nonpregnant women, NSAIDs are widely considered first-line therapy for both acute and chronic pelvic pain. In pregnant women and in those attempting to conceive, NSAIDs are typically avoided. Observational studies have associated NSAID use around the time of conception or prior to 20 weeks' gestation with an increased risk of miscarriage, while acetaminophen has not shown a similar association. NSAID exposure in early pregnancy has also been linked to congenital anomalies.

Guidelines recommend limiting opioid use during pregnancy and in women of childbearing age. Opioid exposure has been associated with congenital anomalies and with poorer maternal and neonatal outcomes. As a result, opioids are generally avoided as first-line therapy for pelvic pain in patients who are pregnant or may be pregnant.

Therefore, it is routine to ascertain pregnancy status prior to administering NSAIDs or opioids to women of childbearing age for an informed decision making discussion. Acetaminophen, in contrast, is generally considered safe in pregnancy and can be administered without delay while awaiting pregnancy testing. Acetaminophen is associated with relatively mild side effects, which may vary by route of administration.

Pharmacokinetic studies demonstrate that intravenous acetaminophen achieves higher peak plasma concentrations and faster central nervous system penetration than oral administration. Outside the ED, IV acetaminophen has been associated with faster onset of meaningful pain relief and reduced opioid use in some surgical populations. Whether these pharmacologic advantages translate into clinically meaningful improvements in acute pelvic pain management in the Emergency Department for patients of childbearing potential with pelvic pain is unclear.

The investigator team hypothesizes that among women aged 16-50 presenting to the emergency department with pelvic pain, patients receiving intravenous acetaminophen will achieve a greater improvement in the numeric rating scale (NRS) pain score at 30 minutes compared with oral acetaminophen.

Study Type

Interventional

Enrollment (Estimated)

140

Phase

  • Phase 4

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

  • United States
    • New York
      • The Bronx, New York, United States, 10467
        • Montefiore Medical Center
        • Contact:
        • Principal Investigator:
          • Eddie M Irizarry, MD

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Child
  • Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Female sex at birth
  • Presentation to the Emergency Department (ED) with pelvic pain
  • Baseline numeric pain score (NRS) ≥4
  • Ability to provide informed consent in English or Spanish

Exclusion Criteria:

  • Receipt of any analgesic medication within 2 hours or acetaminophen within 6 hours
  • Known allergy or intolerance to acetaminophen

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

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

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Active Comparator: Oral Drug + IV Placebo

Oral Acetaminophen 1000mg + IV placebo

Oral Acetaminophen 1000mg

No additional analgesics will be administered prior to two hours unless clinically indicated. Rescue analgesia may be administered at any time at the discretion of the treating clinician.
Drug: Acetaminophen 1000mg PO
Oral Acetaminophen 1000mg
Other: IV Placebo
IV placebo administration
Active Comparator: Intravenous Drug + Oral Placebo

Intravenous Acetaminophen + PO placebo

IV Acetaminophen 1000mg

No additional analgesics will be administered prior to two hours unless clinically indicated. Rescue analgesia may be administered at any time at the discretion of the treating clinician.
Drug: IV Acetaminophen 1000mg
Intravenous Acetaminophen 1000mg
Other: PO Placebo
Oral placebo administration

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Mean Change in Numeric Rating Scale (NRS) score
Time Frame: From baseline to 30 minutes following medication administration
Mean Change in NRS score will be assessed at 30 minutes post-treatment. The NRS is a patient self-assessment pain scale that instructs patients to use a facial grimace scale ranging from 0-10 rating to express pain intensity, wherein 0 is "No pain" and 10 is "Worst pain possible," such that higher scores are indicative of greater pain intensity. For purposes of the primary outcome change in NRS score from baseline will be assessed. Results will be summarized by study arm using descriptive statistics.
From baseline to 30 minutes following medication administration

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Pain Intensity
Time Frame: 0-, 5-, 10-, 15-, 30-, 45-, 60- and 120-minutes following medication administration
Participants will be asked to serially assess their current level of pain intensity as either "Severe," "Moderate," "Mild," or "None." Categorical assessments of pain intensity will be summarized by study arm at each prespecified timepoint.
0-, 5-, 10-, 15-, 30-, 45-, 60- and 120-minutes following medication administration
Time to Clinically Meaningful Reduction in Pain
Time Frame: Within 2 hours after medication administration
Time to clinically meaningful pain reduction as assessed by the Numerical Rating Scale (NRS). The NRS is a pain scale that uses a 0-10 rating to measure pain intensity, where 0 is "No pain" and 10 is "Worst pain possible." Clinically meaningful pain reduction will be defined as achieving a reduction in NRS score of ≥1.3 from baseline. Results will be summarized by study arm using basic descriptive statistics.
Within 2 hours after medication administration
Use of Rescue Medications
Time Frame: Within 2 hours following medication administration
The number/percentage of patients requiring rescue analgesia of any type within 120 minutes will be summarized by study arm using basic descriptive statistics.
Within 2 hours following medication administration
Patient Global Impression of Change (PGI-C) Score
Time Frame: 30- and 120-minutes following medication administration
Effectiveness of treatment will be evaluated using the PGI-C scale. The PGI-C scale is a 7-point self-reported scale used to assess the patient's perception of change in condition/health status following treatment. Patients will provide a single response as to their self-perception of change in condition/health status on a scale ranging from 1 ("Very much improved") to 7 ("Very much worse)" with 4 representing "No change" as the midpoint. Lower scores are indicative of an improved self-assessment of condition following treatment. Scores will be summarized by study arm using descriptive statistics.
30- and 120-minutes following medication administration
Treatment-Related Adverse Events (TRAEs)
Time Frame: Within 2 hours following medication administration
All treatment-related adverse events occurring within 2 hours of medication administration will be recorded and summarized by study arm.
Within 2 hours following medication administration
Emergency Department (ED) Disposition
Time Frame: At 2 hours following medication administration
ED disposition will be summarized at 2 hours. Patients will be categorized as either having been admitted, discharged, or status yet to be determined. Categorical data will be summarized by study arm.
At 2 hours following medication administration
Length of Stay (LOS)
Time Frame: Less than 24 hours following medication administration
Length of stay will be determined based on the time interval between arrival in the ED and disposition determination. Mean LOS will be summarized by study arm.
Less than 24 hours following medication administration
Patient Satisfaction
Time Frame: At 2 hours following medication administration
Patient satisfaction will be determined by asking patients whether they would prefer the same medication which was administered during the study if they returned to the ED with the same condition. The number/percentage of patients who prefer the same medication will be summarized by study arm.
At 2 hours following medication administration

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Montefiore Medical Center

Investigators

  • Principal Investigator: Eddie M Irizarry, MD, Montefiore Medical Center

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

July 30, 2026

Primary Completion (Estimated)

June 30, 2027

Study Completion (Estimated)

June 30, 2027

Study Registration Dates

First Submitted

May 12, 2026

First Submitted That Met QC Criteria

May 12, 2026

First Posted (Actual)

May 19, 2026

Study Record Updates

Last Update Posted (Actual)

May 20, 2026

Last Update Submitted That Met QC Criteria

May 18, 2026

Last Verified

May 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 2025-17368

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

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

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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