Clinical Correlates of Endometriosis in Patients with Interstitial Cystitis

Objectives: Interstitial cystitis/bladder pain syndrome (IC/BPS) presents as chronic pelvic pain attributed to the bladder in the absence of infection. Previous research indicates a heightened association between IC/BPS and non-urological associated symptoms (NUAS), including endometriosis. This study aims to contribute to the existing literature by examining the prevalence of concurrent endometriosis in a large IC/BPS patient registry and comparing relevant clinical outcomes and disease characteristics between the patients who have IC/BPS with concurrent endometriosis and patients who have IC/BPS without concurrent endometriosis.

Methods: We assessed the prevalence of endometriosis among female patients (n=533) in our IC/BPS registry undergoing therapeutic hydrodistension. Patient-reported history and medical records were utilized for endometriosis diagnosis. Current Procedural Terminology (CPT) and International Classification of Diseases (ICD) codes identified patients with prior cystectomy and/or hysterectomy. Co-occurring diagnoses were recorded from patient reports and medical records. Univariate analysis compared demographics and clinical features between participants with and without concurrent endometriosis. Binary logistic regression was performed to identify which symptomatology variables was associated with IC/BPS and endometriosis cooccurring diagnosis.

Results: Among the 533 patients examined, 108 (20.3%) reported a history of endometriosis. Those with concurrent endometriosis demonstrated a younger overall age (p=0.009), a younger age at IC/BPS diagnosis (p=0.020), higher bladder capacity (p=0.006), and underwent cystectomy at an earlier age (p=0.026 in a subgroup of 40 patients) compared to those without. Furthermore, they exhibited higher NUAS scores (p < 0.001). Furthermore, patients with IC/BPS and concurrent endometriosis had higher bladder capacity and were less likely to have a history of cystectomy (p < 0.05). They were also less likely to report the presence of allergies (p=0.03). Conversely, they were more prone to report experiencing co-morbidities such as chronic pelvic pain, chronic fatigue, fibromyalgia, migraines, and chronic pelvic dysfunction. Binary logistic regression identified a positive association between endometriosis and chronic pelvic pain, while a negative association between allergies and low bladder capacity was found for concurrent endometriosis.

Conclusions: In our patient population, approximately 20% of patients with IC/BPS had concurrent endometriosis. Patients with IC/BPS and concurrent endometriosis were more likely to have earlier diagnosis of IC/BPS, higher bladder capacity, increased NUAS scores, increased co-morbid conditions and an earlier age at time of cystectomy.