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CompletedPhase 4

Mechanistic Characterization of Uterine Pain

Key facts

Who runs it
Endeavor Health
Where
Evanston, United StatesSee the site
Trial code
Status
Completed
Phase
Phase 4
People taking part
183 people enrolled
Started
25 Oct 2019
Ended
23 Jul 2025
Type of study
Interventional, 2 groups
Treatments tested
  • Naproxen Sodium
  • Placebo
Record updated
23 September 2026

Who can take part

Age
18 years to 45 years
Sex
Women only
Healthy volunteers
Can take part

The registry criteria, word for word

Show all 22 criteriaShow less

Who cannot take part

  • active genitourinary or sexually transmitted infection; Provisional exclusion for primary analyses for all study participants: Acute or chronic conditions associated with pelvic pain with a defined anatomical cause other than endometriosis or leiomyoma (e.g., pathological ovarian cysts, significant persistent hydro/hematosalpinx, untreated pelvic inflammatory disease, active pelvic or abdominal malignancies, Mullerian anomalies, or stage 3 uterine prolapse), and comorbid diagnosis of significant leiomyoma and endometriosis; Note: these exclusion criteria may be incidentally discovered after the MRI scan and confirmed with a radiologist's or Dr. Tu's diagnosis; Provisional exclusion for adenomyosis group: Because the frequency of adenomyosis is low or unknown, and may consist of multiple subtypes resulting in heterogeneity and inadequate statistical power, adenomyosis patients are not a planned study group and diagnosed cases will be initially excluded from recruitment. Focal and diffuse adenomyosis will be excluded by guidelines (Chapron et al., 2017) adapted from the Kishi criteria (Kishi et al., 2012): maximal junctional zone thickness exceeding 12 mm, a ratio of junctional zone thickness to myometrium exceeding 40%, or high-intensity foci within the myometrium. If a substantial number of adenomyosis participants participate, as discovered after-the-fact with MRI, results will be analyzed; Intermediate levels of dysmenorrhea pain exclusion: Participants with mild menstrual pain (between 3 and 5 on a 0-10 scale) will be excluded. Our prior experience with this cohort (Westling et al., 2013) suggests that The investigators may encounter a floor effect when studying the effectiveness of NSAIDs. Also, since this cohort is most likely to respond to NSAIDs, it is imperative The investigators study the mechanisms of the most severe sufferers of refractory menstrual pain
  • Menstruation-related exclusion criteria for all study participants: The investigators will exclude certain participants with conditions associated with the absence of regular menses such as polycystic ovarian syndrome, pregnancy, current use of any continuous hormonal medication or contraceptive, or Asherman's syndrome
  • history of metallic implants,
  • history of metallic injury,
  • any diagnosed condition that would preclude investigation with MRI (e.g., claustrophobia),
  • allergy or inability to tolerate naproxen
  • renal disorders,
  • liver disorders,
  • von Willebrand disease,
  • gastrointestinal conditions or surgeries that would affect naproxen absorption,
  • platelet disorders,
  • Age restrictions for all study participants: Regularly menstruating women (age 18-45) will be identified using our well-tested community-wide recruitment strategy, including approaching our division's busy gynecological disorders clinic, and the departments of Ob/Gyn at NorthShore and the University of Chicago. Although women above the age of 45 can have menstrual pain, irregularities in perimenopause could cause confounding effects on uterine physiology and scheduling difficulty. Similarly, irregularities in menstruation, ovulation, and pain levels in participants under age 18 could potentially detract from meaningful interpretation of phenotypes (Seidman et al., 2018). Additionally, before age 18, the uterus is still developing and substantially increasing in size (Porcu et al., 1989; Verguts et al., 2013). Thus, to limit potential confounding effects, participants under the age of 18 will be investigated in a separate study
  • MRI-related or participation related exclusion criteria for all study participants:
  • The investigators will exclude participants with criteria that would affect our ability to obtaining meaningful MRI data such as
  • presence of an intrauterine device (IUD). The use of an IUD potentially affects interpretability of MRI because it creates an imaging artifact in the endometrium extending to the myometrium
  • inability to read or comprehend the informed consent written in English,
  • BMI >40,
  • thyroid dysfunction,
  • adrenal dysfunction,
  • coagulopathy,
  • prolactinoma,
  • diabetic neuropathy,

Where in United States

  • NorthShore University HealthSystemEvanston, United States

About the trial

What the trial wants to find out

There are limited treatment options for management of dysmenorrhea, and the physiological processes they affect are not completely understood. For example, NSAIDs are effective in reducing menstrual pain in some women by inhibition of prostaglandin synthesis, but whether those effects are mediated by affecting contractility, perfusion, or hypoxemia is unknown. Understanding how these drugs relieve menstrual pain (and why they fail) would be of substantial clinical significance. Given the foregoing, Two Specific Aims are proposed:

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Aim #1: Characterize menstrual pain phenotypes associated with impairments in myometrial activity, perfusion, and/or oxygenation. Continuous MRI scans of the uterus will be performed with simultaneous measurement of self-reported pain in healthy women and those experiencing menstrual pain. The investigators will include cohorts of women with imaging diagnosed leiomyoma and surgically-confirmed endometriosis to evaluate the contribution of structurally identifiable factors. Based on preliminary data, the investigators anticipate finding four phenotypes with menstrual pain related to: 1) myometrial activity, 2) inadequate perfusion and/or oxygenation, 3) a combination of phenotypes 1 \& 2, and 4) a non-uterine source.

Aim #2: Evaluate the effects of naproxen on myometrial activity, perfusion, and/or oxygenation with respect to pain relief. In women with primary dysmenorrhea, the investigators will acquire pelvic MRI scans and evaluate self-reported menstrual cramping pain before and after administration of randomized naproxen or placebo.

Naproxen could principally affect one or more potential sources of uterine pain such as myometrial activity, perfusion, and/or oxygenation. The investigators will corroborate preliminary data findings, which suggest menstrual phenotypes with myometrial activity will be more likely to respond. Conversely, Aim 2 will also elucidate the mechanisms responsible for inadequate pain relief from naproxen.

Bioavailability of naproxen levels and other molecules associated with NSAID-resistance will be evaluated from the serum of participants after taking naproxen using HPLC-MS.

The 2 groups in the trial

  • Naproxen First, Then PlaceboTreatment being tested

    Participants randomized to this sequence take a single oral 550 mg naproxen sodium tablet at the first menstrual MRI visit and a matching placebo pill at the second MRI visit (a subsequent menstrual episode, 1-2 months later). At each visit the pill is taken immediately after the pre-treatment scan, approximately 90 minutes before the post-treatment scan. Allocation is quadruple-masked: assignment was randomized in REDCap using a block size known only to the study statistician, with naproxen and identical-appearing placebo dispensed in coded containers by the clinical research pharmacy.

    Treatment: Naproxen Sodium and Placebo

  • Placebo First, Then NaproxenTreatment being tested

    Participants randomized to this sequence take a matching placebo pill at the first menstrual MRI visit and a single oral 550 mg naproxen sodium tablet at the second MRI visit (a subsequent menstrual episode, 1-2 months later). Pill timing relative to the scans, blinding, randomization, and pharmacy dispensing are identical to the other sequence.

    Treatment: Naproxen Sodium and Placebo

Data and sources

Registry record
Listed on ClinicalTrials.gov.
Official title
Mechanistic Characterization of Uterine Pain (MCUP) to Improve Diagnosis and Treatment for Dysmenorrhea
Record updated
23 September 2026