Chronic pelvic pain affects up to 147 per 1,000 women. The etiology of the pain is frequently difficult to determine. Clemons and colleagues suspected that many cases are the result of interstitial cystitis and sought to demonstrate this using a combination of a validated screening questionnaire and laparoscopy plus cystoscopy in women being investigated for chronic pelvic pain.

Women older than 18 years who were scheduled for laparoscopy for chronic pelvic pain at a university center were eligible for the study if they had no history of interstitial cystitis diagnosis, no bladder or gynecologic tumors, and no urinary-tract infection within the previous four weeks. Women with untreated genital herpes, Chlamydia, gonorrhea, vaginitis, urinary-tract calculi or diverticula, and those who were at risk for cystitis because of radiation, chemotherapy, or tuberculosis also were excluded.

The 45 participants were interviewed to collect data on symptoms and complete the Interstitial Cystitis Symptom Index and Problem Index questionnaires (see O'Leary MP, Sant GR, Fowler FJ Jr, et al. The interstitial cystitis symptom index and problem index. Urology 1997;49:58–63). Chart review and urinary and cervical-swab screening were used to ensure that women did not have any conditions that would exclude them from the study. Cystoscopy with bladder hydrodistention and targeted biopsy were performed under anesthesia at the time of diagnostic laparoscopy. A diagnosis of interstitial cystitis required three criteria (i.e., a history of urinary urgency, plus urinary frequency [eight or more voids during waking hours] or nocturia [two or more voids each night], plus diagnostic cystoscopy findings [glomerulations or Hunner's ulcers]). A diagnostic cut-off value of 5 on the index was used to assess the performance of the screening questionnaire in identifying cases of interstitial cystitis.

The mean age of the 45 patients was 35 years, and the patients reported having an average of 71 months of chronic pelvic pain (range, six to 120 months). All had experienced at least one previous intervention, including laparoscopy in 45 percent and hysterectomy in 9 percent. Participants reported an average pelvic-pain score of 8 on a zero to 10 scale and scored a median 7 on the Interstitial Cystitis Symptom Index and 5 on the Problem Index.

As shown in the accompanying table, 17 women (38 percent) met diagnostic criteria for interstitial cystitis. Eleven of the women with this condition also had pathologic findings on laparoscopy. Univariate analysis to determine risk factors for interstitial cystitis identified the score on the symptom and problem indexes, pain score for dyspareunia, and a history of one or more urinary-tract infections per year as significant. Scores of 5 or more on the symptom index were associated with a sensitivity of 94 percent, specificity of 50 percent, positive predictive value of 53 percent, and negative predictive value of 93 percent in diagnosing interstitial cystitis. Backward logistic regression demonstrated a symptom score of 5 or more and a dyspareunia score of 7 or more as independent risk factors. When both were present, the sensitivity for diagnosis of interstitial cystitis was 76 percent, with specificity of 82 percent, positive predictive value of 72 percent, and negative predictive value of 85 percent.

The authors conclude that interstitial cystitis should be seriously considered as the cause of, or a contributor to, chronic pelvic pain and might be present in approximately one third of patients with this type of pain. Elevated scores for dyspareunia and cystitis symptoms are significant risk factors, and the Interstitial Cystitis Symptom Index serves as a useful screening tool.