Role of bowel pathophysiology in voiding dysfunction

A great deal of neural overlap and “cross-talk” exists among the pelvic viscera, a prerequisite for normal pelvic physiologic function. However, after an acute or chronic irritative or infectious pelvic insult, pelvic “cross-sensitization” may occur, leading to the development of chronic pelvic pain and its associated and/or overlapping disorders. As such, comorbid pathophysiologic alterations of the bowel and bladder are common, as exemplified by the overlap of irritable bowel syndrome and interstitial cystitis/painful bladder syndrome, the two most common chronic pelvic pain disorders. Although less common, voiding dysfunction may likewise be seen in inflammatory bowel disease (ulcerative colitis and Crohn’s disease) and diverticulitis. In support of these clinical associations and shedding further light on the role of bowel pathophysiologic mechanisms in voiding dysfunction, in bowel → bladder cross-sensitization studies conducted by the authors, colonic irritation induced irritative micturition patterns (both acutely and chronically) and sensitized the mechanoreceptive and chemoreceptive properties of urinary bladder C-fibers. Furthermore, convergence of bowel and bladder afferents was seen at the peripheral level and may also play a role. Thus, physiologic functions of the bowel and bladder are intimately related by neural pathways and are at risk for comorbid disease associations.