Constipation and LUTS - how do they affect each other?

CONTEXT: Urinary bladder and rectum share a common embryological origin. Their autonomic and somatic innervations have close similarities. Moreover, the close proximity of these two organ systems could suggest that dysfunction in one may influence, also mechanically, the function of the other. Therefore, it is not surprising that defecation problems and lower urinary tract symptoms (LUTS) occur together, as reported in the literature.
OBJECTIVE: To study the relationship between constipation and LUTS focusing on what is evidence-based. EVIDENCE ACQUISITION: We searched the Medical Literature Analysis and Retrieval System Online (MEDLINE) database in February 2010 to retrieve English language studies (from 1997 to 2009) and the 2005, 2006 and 2007 abstract volumes of the European Association of Urology (EAU), American Urological Association (AUA) and International Continence Society (ICS). EVIDENCE SYNTHESIS: We present the findings according to the studied population in four groups: (a) children, (b) middle-aged women, (c) elderly and (d) neuropathic patients. Most published studies that correlated rectal and bladder dysfunction were carried out in children or in young women. On the other hand, there are few studies regarding the association between constipation and LUTS in the elderly and in neuropathic patients.
CONCLUSIONS: Several studies in children documented that constipation is linked to urinary tract problems, including infections, enuresis, vesicoureteral reflux and upper renal tract dilatation. The underlying pathophysiology of these findings has not yet been clearly defined. Studies in middle-aged women also support a high prevalence of constipation among patients suffering from urinary tract dysfunction. Furthermore, an association between constipation and urinary incontinence, as well as between constipation and pelvic organ prolapse, has been suggested. The only prospective study in constipated elderly with concomitant LUTS demonstrates that the medical relief of constipation also significantly improves LUTS. Finally, the available data on neuropathic patients suggest that stool impaction in the rectum may mechanically impede bladder emptying. However, most of the studies only include a small number of patients, are not prospective and are uncontrolled. Therefore, there is a need for large-scale, controlled studies to further improve evidence and to provide a valid recommendation for all groups, especially for the elderly and neuropathic patients.