A Novel Method of Urinary Sphincter Deficiency: Serial Histopathology Evaluation in a Rat Model of Urinary Incontinence.

In this study, a novel technique of irreversible sphincter deficiency by pudendal nerve transection (PNT) using 40 female rats for studying the pathophysiology of stress urinary incontinence associated with childbirth was developed. Of the 40 rats, 10 served as controls and the remaining underwent bilateral PNT at the anastomotic lumbosacral trunk level. Urethral morphological changes following bilateral PNT were assessed with serial hematoxylin and eosin (H&E) and immunohistochemistry (IHC) staining methods at 50, 90, and 130 days post-intervention. Leak point pressure (LPP) measurement was used to determine the effect of pudendal injury on urethral outlet resistance after the transection. H&E and IHC staining showed irreversible loss of striated muscle mass of the sphincter region and increase in collagen deposition compatible with muscle atrophy. LPP measurements also significantly decreased following bilateral PNT. In conclusion, a novel method of irreversible sphincter insufficiency was developed. This model effectively decreased urethral outlet resistance and caused irreversible striated muscle atrophy. It was suggested that this technique can be used to develop a permanent sphincter deficiency model for the preclinical testing of treatment modalities exclusively triggering the pudendal nerve.