The prevalence of interstitial cystitis in gynecologic patients with pelvic pain, as detected by intravesical potassium sensitivity

OBJECTIVE: The purpose of this study was to determine the prevalence of interstitial cystitis in a large number of gynecologic patients with pelvic pain versus control subjects, as indicated by a positive result on a potassium sensitivity test. STUDY DESIGN: Gynecologists at four US medical centers administered the potassium sensitivity test to consecutive unselected patients with pelvic pain and control subjects. Before testing, each patient with pelvic pain was given an initial clinical diagnosis on the basis of the chief symptomatic complaint(s) and was surveyed for urologic symptoms. RESULTS: Of 244 patients with pelvic pain, 197 patients (81%) had a positive result from a potassium sensitivity test. Positive potassium sensitivity test rates were comparable across all four sites and all clinical diagnoses that included endometriosis, vulvodynia (vulvar vestibulitis), and pelvic pain. Urologic symptoms were reported by 84% of patients, but only 1.6% of the patients had received an initial diagnosis of interstitial cystitis. None of the 47 control subjects were tested positive with the potassium sensitivity test. CONCLUSION: Interstitial cystitis may be a common unrecognized cause of pelvic pain in gynecologic patients and deserves greater, if not primary, consideration in the differential diagnosis of pelvic pain.