Low-pressure hydrodistension induces bladder glomerulations in female patients with interstitial cystitis/bladder pain syndrome

Aims: The role of hydrodistension in the diagnosis of interstitial cystitis/bladder pain syndrome (IC/BPS) is controversial. This study evaluated the effect of low-pressure hydrodistension on glomerulation formation in female patients diagnosed with the disease. Methods: Sixty female patients with the clinical diagnosis of IC/BPS and 30 female controls without the disease underwent cystoscopy and hydrodistension. Cold-cup biopsy was taken from bladder posterior wall at sites with normal cystoscopic appearance before hydrodistension in the IC/BPS group. The tissue samples were processed for histology study. Low-pressure (40 cmH₂O) hydrodistension for 2 min was performed and the appearance of glomerulations was compared between the two groups. High-pressure (80 cmH₂O) hydrodistension for 8 min was then performed as a therapeutic measure for the IC/BPS patients. Further changes to the degree of glomerulations were recorded. Results: Histology showed pathological changes in the normal-appearing IC/BPS bladder mucosa including urothelium denudation, inflammatory cell infiltration, stromal edema, fibrosis, and vascular congestion. Low-pressure hydrodistension induced significant glomerulation formation in the patient group (percentage of patients with Grades 0–4: 0%, 8.3%, 40%, 35%, 10%, respectively) while none in the controls. High-pressure hydrodistension further increased the glomerulation grading in the IC/BPS patients. Conclusions: Structural changes are present in prehydrodistension IC/BPS bladder wall, which may not be macroscopically detectable. Hydrodistension at low pressure is adequate to disrupt the integrity of such diseased mucosa and offers a more discriminative test in the diagnosis of IC/BPS.