Repeated vaginal balloon dilatation for Chronic stress incontinence modeling in Sprague Dawley female rats

Abstract ObjectivesVaginal distention (VD) serves as a validated model for studying birth-related trauma in rats. This study evaluated the effect of repeated vaginal balloon dilatation for chronic stress incontinence modeling in Sprague Dawley female rats.MethodsThirty mature female Sprague Dawley rats (200–250 g) were obtained from the Medical Experimental Research Center, Mansoura Faculty of Medicine. Rats were divided into three groups: (A) Control (no treatment), (B) Acute VD (single vaginal distension, euthanized after 2 weeks), and (C) Chronic VD (VD repeated at 0,2, and 4 weeks). Urodynamic was assessed by abdominal leak peritoneal pressure (ALPP) and urethral specimens were evaluated using hematoxylin/eosin, and Masson staining.ResultsThe study established a chronic urinary stress incontinence (USI) model using repeated vaginal distension (VD), confirmed by significantly lower abdominal leak point pressure (ALPP) in both acute (0.25 ± 0.15 mmHg) and chronic (0.37 ± 0.13 mmHg) models compared to controls (1.41 ± 0.3 mmHg, P < 0.0001). Histopathological analysis revealed muscle fiber thinning, edema, and fibrosis, with urethral thickness progressively decreasing from controls (402.3 ± 41.54 µM) to acute (197.6 ± 5.318 µM) and chronic (166.6 ± 7.323 µM) models (P < 0.0001). These findings validate the model’s effectiveness in replicating chronic USI-associated structural deterioration.ConclusionsThe current data showed the validity of repeated vaginal balloon dilatation as a model to study chronic SUC better than the single dilatation model. This approach addresses the shortcomings of the conventional VD model by more accurately reflecting the progressive characteristics of pelvic floor weakening. This may enhance the accuracy of preclinical studies and improve therapeutic outcomes for patients with SUI.