Contribution of the sphincter of O'Beirne in the pathophysiology of slow transit constipation as shown by low resolution manometry

Background: Key features of the pathophysiology of slow transit constipation are known. Colonic motility is markedly reduced, related to increased sympathetic activity, and retrograde propulsive activity is present, originating from the rectosigmoid junction (the sphincter of O'Beirne) and rectum. Furthermore, the sphincter of O'Beirne does not persistently relax when propulsive motor activity descends upon it, creating a barrier for stool transit into the rectum. Methods: Our aim was to assess whether low-resolution manometry can provide information on the role of the sphincter of O'Beirne in patients with chronic slow transit constipation. To this end, we analyzed archival 24-h colonic manometric tracings from patients with slow transit constipation to assess the presence and characteristics of the sphincter of O'Beirne. Results: Reliable tracings were obtained from 23 patients with a confirmed recording port at the sphincter location. Although colonic activity was significantly reduced to about 3% of normal, the activity of the sphincter of O'Beirne showed normal activity, with 10% of the activity comprised of the 3 cycles/min cyclic motor activity. Conclusion: In conclusion, the sphincter of O'Beirne is not dysfunctional in chronic constipation; however, because of its continued presence and the lack of propulsive activity that relaxes the sphincter through a functional colo-anal reflex, it contributes to the symptoms of constipation.