Submitted on June 8, 2006
Accepted on September 26, 2006
The Effects of Pelvic Floor Muscle Contraction on the Anal Canal Pressure
Bikram Singh Padda1, Sung-Ae Jung2, Dolores Pretorius3, Charles Nager4, Debbie Den-Boer1, and Ravinder K. Mittal1*
1 Gastroenterology, University of California, San Diego, San Diego, California, United States
2 Ewha Womans Univ College of Medicine, Seoul , Korea, Republic of; Gastroenterology, University of California, San Diego, San Diego, California, United States
3 Radiology, Univerisity of California, San Diego, San Diego, California, United States
4 Dept of Reproductive Medicine, University of California San Diego, San Diego, California, United States
* To whom correspondence should be addressed. E-mail: rmittal{at}ucsd.edu.
Introduction: The role of pelvic floor muscle contraction in the genesis of anal canal pressure is not clear. Recent studies suggest that vaginal distension increases the pelvic floor muscle contraction. Methods: We studied the effects of vaginal distension on the anal canal pressure in 15 nullipara asymptomatic women. Anal pressure, rest and squeeze were measured using station pull-through manometry technique with no vaginal probe, 10 mm vaginal probe and 25 mm vaginal probe in place. Results: Rest and squeeze vaginal pressures were significantly higher when measured with the 25 mm as compared to the 10 mm probe suggesting that vaginal distension enhances pelvic floor contraction. In the presence of the 25 mm vaginal probe, the rest and squeeze anal pressures in the proximal part of the anal canal are significantly higher as compared to the no vaginal probe or the 10 mm vaginal probe. On the other hand, the distal anal pressures are not affected by any of the vaginal probes. Ultrasound imaging of the pelvic floor revealed that vaginal distension increases the anterior-posterior length of the puborectalis muscle. Atropine, 15 µg/kg had no influence on the rest and squeeze anal pressure, with or without vaginal distension. Discussion: We propose that pelvic floor contraction plays an important role in the fecal continence mechanism by increasing anal canal pressure.
