Lidocaine-prilocaine Cream as Analgesia for In-office Levator Muscle Trigger Point Injections

Up to 23% of women with chronic pelvic pain have a component of pelvic floor myofascial pain, described as hypertonic, tender pelvic floor muscles with sensitive trigger points. The mainstay of treatment for pelvic floor myofascial pain is pelvic floor physical therapy. However, some areas of hypertonicity may be refractory to physical therapy and require alternative treatment strategies such as steroids, nonsteroidal anti-inflammatory drugs, muscle relaxants, antidepressants, and TPI. TPI of a local anesthetic with or without steroids or botulinum toxin have shown improvement in pelvic pain associated with pelvic floor dysfunction. Transvaginal TPI are commonly performed for patients in the office, as well as in the operating room with sedation or general anesthesia. Acute pain with prior in-office TPI or fear of pain is a common reason that patients elect for TPI in the operating room, which is associated with higher healthcare cost and clinical risk.

There is growing interest in analgesic options with in-office gynecologic procedures. The American College of Obstetricians and Gynecologists released a Clinical Consensus outlining the urgent need for providers to have a better understanding of pain-management options and avoid underestimating patient pain during in-office procedures.

Topical anesthetics have been extensively studied in different populations for a range of needle procedures and more recently have been shown to be effective in reducing pain during minor gynecologic procedures. Lidocaine-prilocaine cream is a well-tolerated topical anesthetic, which has demonstrated safety in pediatric and geriatric populations. It is FDA-approved for use on genital mucus membranes.

This study is a single-institution, pilot, randomized, double-blinded, placebo-controlled trial comparing the efficacy of lidocaine-prilocaine cream with placebo for analgesia during office-based levator muscle trigger point injection in women with myofascial pelvic pain. Study Period: August, 2026 to July, 2028.

Key study personnel (KSP) at the Urogynecology and Reconstructive Pelvic Surgery Office will identify and enroll patients with myofascial pelvic pain undergoing trigger point injection at their procedural visit. Patients who agree to participate in the study will be consented via consent forms at their procedural visit. Patients will be randomized using block randomization to one of two groups: pre-procedural treatment with lidocaine-prilocaine cream or placebo cream. The lidocaine-prilocaine cream and the placebo cream are both unscented, the same color and texture. They will both be dispensed in identical packaging to ensure study personnel; Urogynecology attending and fellow physicians as well as the patient are blinded to the study assignment. KSP will bring the correct medication to the room for provider application.

Specifically, the provider will apply either 5 grams of 2.5% lidocaine-prilocaine cream or 5 grams of the placebo cream with a single, gloved digit to the posterior vaginal epithelium, along the planned distribution of TPI approximately 10 minutes prior to the procedure.

Participants will indicate the severity of their pelvic floor pain immediately prior to administration of the intervention medication using a 100 mm visual analog scale, during the procedure, and immediately post-procedure. The scales will be provided on paper for participants to complete and be marked with a unique patient identification number. The completed scales will be collected by KSP and stored confidentially.

Given that this is a medication intervention study, we have asked Dr. Nicole Korbly, Assistant Professor and Clinical Educator at the Warren Alpert Medical School of Brown University and Division of Urogynecology and Reconstructive Pelvic Surgery to serve as Data Safety Monitor. Every three to six months she will review the data, as well as any and all adverse events and ensure proper reporting to the Institutional Review Board.

Inclusion criteria

• Patients 18 years or older
• Patients who are undergoing in-office levator muscle trigger point injection for myofascial pelvic pain
• Able to give informed consent for the study

Exclusion criteria

• Documented allergy to lidocaine or prilocaine
• Use of lidocaine or prilocaine within last 72 hours