Missed diagnoses are identified in the majority of patients referred for subspecialty evaluation of interstitial cystitis

Interstitial cystitis/ bladder pain syndrome (IC/BPS) is technically a diagnosis of exclusion. Previous studies have reported, for example, bladder cancer in patients initially misdiagnosed with IC/BPS . The current aim is to explore the frequency of underlying primary diagnoses in new patients referred with existing diagnoses of IC/BPS. This is an observational cohort study of new patients who presented with an existing diagnosis of IC/BPS to a subspecialty urology urogynecology and reconstructive pelvic surgery (URPS) clinic from January 1, 2022 to March 1, 2024. IC/BPS was defined as present at initial intake if the patient reported the diagnosis, if the ICD-10 code 30.1, 20.10, 30.11 had been previously coded, or if IC/BPS-specific treatments were documented (e.g. pentosan polysulfate). Data on individualized work-up were recorded. The primary outcome was a final diagnosis of interstitial cystitis versus reclassification. Of 50 patients carrying a diagnosis of IC/BPS at initial evaluation, 24% (n=12) retained the diagnosis, while 76% (n=38) were reclassified. These included 12 (32%) with small fiber neuropathy, 9 (24%) with bladder neck obstruction, 5 (13%) with peripheral neuropathy other than SFN via EMG (including 1 with large fiber neuropathy, 1 with diabetic neuropathy, and 3 unspecified), and 2 (5%) with symptomatic Tarlov cyst, 2 (5%) with severe lumbar spinal stenosis with underactive bladder, 2 (5%) with metabolically relevant MTHFR gene mutation, 2 (5%) upper motor neuron bladder with severe VUR and one each of post-chemotherapy neuropathy, stone in the distal ureter, atonic bladder and straightforward prostatic obstruction. The majority (76%) of patients referred for subspecialty pelvic pain evaluation carrying a history of IC/BPS were found to have an alternate underlying physiologic diagnosis. Detailed history, review of systems, and targeted reevaluation can help distinguish IC/BPS from identifiable pathology.