Interstitial cystitis and endometriosis in patients with chronic pelvic pain: The "Evil Twins" syndrome.

OBJECTIVE: To determine the prevalence of interstitial cystitis and endometriosis in patients with chronic pelvic pain. METHODS: A prospective analysis was conducted in 178 women with CPP who presented with bladder base/anterior vaginal wall and/or uterine tenderness, with or without irritative voiding symptoms. The Potassium Sensitivity Test was used to assess bladder epithelial dysfunction. Patients were evaluated with concurrent laparoscopy and cystoscopy with hydrodistention. RESULTS: Laparoscopic findings among the 178 patients with chronic pelvic pain supported a diagnosis of endometriosis in 134 (75%) patients, and cystoscopy confirmed a diagnosis of interstitial cystitis in 159 (89%) patients. Both interstitial cystitis and endometriosis were diagnosed in 115 patients (65%). The Potassium Sensitivity Test was positive in 146 (82%) patients, with 140 (96%) of these patients diagnosed with interstitial cystitis and 105 (72%) with endometriosis. CONCLUSIONS: Results of this prospective study show that interstitial cystitis and endometriosis may frequently coexist in patients with chronic pelvic pain. A positive Potassium Sensitivity Test accurately predicted the presence of interstitial cystitis in 96% of these patients with chronic pelvic pain, as confirmed by cystoscopic hydrodistention. It is necessary to consider the diagnosis of endometriosis and interstitial cystitis concurrently in the evaluation of patients with chronic pelvic pain to avoid unnecessary delay in identifying either condition.