Influence of Body Position and Stool Characteristics on Defecation in Humans

Rao, Satish S.; Kavlock, Renae; Rao, Sheila

doi:10.1111/j.1572-0241.2006.00827.x

Cited by 127 publications

(124 citation statements)

References 18 publications

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“…A second possibility is that a transient contraction of the puborectalis would allow the individual to sense whether the contents are solid, which would have a weight and mass to press against during the SMR, rather than gas. The consistency of rectal contents has previously been shown to influence defecation (17). This concept also explains why the SMR is associated with the desire to defecate.…”

Section: Discussionmentioning

confidence: 78%

Investigation of anal motor characteristics of the sensorimotor response (SMR) using 3-D anorectal pressure topography

Cheeney

Troche

Attaluri

et al. 2011

American Journal of Physiology-Gastrointestinal and Liver Physi

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Desire to defecate is associated with a unique anal contractile response, the sensorimotor response (SMR). However, the precise muscle(s) involved is not known. We aimed to examine the role of external and internal anal sphincter and the puborectalis muscle in the genesis of SMR. Anorectal 3-D pressure topography was performed in 10 healthy subjects during graded rectal balloon distention using a novel high-definition manometry system consisting of a probe with 256 pressure sensors arranged circumferentially. The anal pressure changes before, during, and after the onset of SMR were measured at every millimeter along the length of anal canal and in 3-D by dividing the anal canal into 4 ϫ 2.1-mm grids. Pressures were assessed in the longitudinal and anterior-posterior axis. Anal ultrasound was performed to assess puborectalis morphology. 3-D topography demonstrated that rectal distention produced an SMR coinciding with desire to defecate and predominantly induced by contraction of puborectalis. Anal ultrasound showed that the puborectalis was located at mean distance of 3.5 cm from anal verge, which corresponded with peak pressure difference between the anterior and posterior vectors observed at 3.4 cm with 3-D topography (r ϭ 0.77). The highest absolute and percentage increases in pressure during SMR were seen in the superior-posterior portion of anal canal, reaffirming the role of puborectalis. The SMR anal pressure profile showed a peak pressure at 1.6 cm from anal verge in the anterior and posterior vectors and distinct increase in pressure only posteriorly at 3.2 cm corresponding to puborectalis. We concluded that SMR is primarily induced by the activation and contraction of the puborectalis muscle in response to a sensation of a desire to defecate. anal manometry; puborectalis IN HUMANS, BALLOON DISTENTION of the rectum normally induces the recto-anal inhibitory reflex (RAIR) (6, 11) as well as the recto-anal contractile reflex (RACR) (9, 10, 21). RAIR is an enteric neuronal reflex that is mediated by nitric oxide, vasoactive intestinal peptide, and adenosine triphosphate and causes relaxation of internal anal sphincter (IAS) (18). The rate and method of rectal distention (intermittent vs. ramp) affect the properties of the RAIR, and this reflex response is classically absent in Hirschsprung's disease and other conditions such as after circular rectal myotomy and after lower anterior resection (4,12,22).In addition to the aforementioned reflexes, recently, we have described the sensorimotor response (SMR) (5) that is also seen during balloon distention of the rectum. The SMR is a transient anal contraction that is usually seen overlying the initial relaxation phase of the RAIR (5). In healthy subjects, it coincides with the onset of a sensation for defecation (5). A recent study showed that the SMR was abnormal in patients with rectal hyposensitivity, suggesting a pathophysiological role for this response in anorectal disorders (19). However, the precise origin of the anal contractile response, in particular...

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Section: Discussionmentioning

confidence: 78%

Investigation of anal motor characteristics of the sensorimotor response (SMR) using 3-D anorectal pressure topography

Cheeney

Troche

Attaluri

et al. 2011

American Journal of Physiology-Gastrointestinal and Liver Physi

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“…A study reported that an assessment of bowel movements could be made most appropriately in the sitting position. 24 This study has several limitations. First, only 46% of the total patients received biofeedback training with EMG.…”

Section: Discussionmentioning

confidence: 99%

Balloon Expulsion Test Does Not Seem to Be Useful for Screening or Exclusion of Dyssynergic Defecation as a Single Test

Lee

Hong

Kim

et al. 2017

J Neurogastroenterol Motil

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Background/AimsBalloon expulsion test (BET) is regarded as a screening tool of dyssynergic defecation (DD). However, some patients with normal BET results may be treated effectively by biofeedback training. This study aims to validate BET as a single screening test. MethodsTwo hundred and thirty-two patients who were diagnosed with functional constipation or irritable bowel syndrome with constipation who underwent anorectal manometry (ARM) and BET at Seoul National University Hospital were enrolled. We evaluated the validity of BET based on ARM and electromyography (EMG) during biofeedback training. ResultsIf BET ≤ 1 minute was defined as normal, sensitivity and negative predictive value (NPV) of BET in predicting paradoxical contraction based on ARM findings were 71.4% and 13.9%. If BET ≤ 3 minutes was defined as normal, sensitivity and NPV were 35.2% and 6.6%. Specificity and positive predictive value (PPV) of BET ≤ 3 minutes criteria were 84.8% and 93.3%. Same analysis was conducted in 107 patients who underwent EMG during biofeedback training. With 1-minute criteria, sensitivity and NPV of BET were 70.3% and 14.3%. With 3 minutes criteria, sensitivity and NPV of BET was 38.6% and 8.8%. Specificity and positive predictive values were both 100.0%. ConclusionsBased on either ARM or EMG during biofeedback training, sensitivity was at most 71.4% and NPV was less than 15.0% irrespective of whether BET was within 1minute or within 3 minutes. BET seems to have a limitation as both a screening test for dyssynergic defecation and a simple assessment to rule out the necessity of biofeedback training.

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“…Meanwhile, one recent study recommended a FECOM with the result that stool-like sensation was more commonly evoked by FECOM than balloon. 7 …”

Section: Filling Volume Of the Balloonmentioning

confidence: 99%

“…8 However, recent studies and laboratories suggested that sitting position appears to be more conductive for defecation than the lying position showing that 36% of normal healthy subjects exhibited a dyssynergic pattern in the lying position. 7 Since sitting is an actual defecation posture and provides more driving force to defecate, it is desirable for patients to perform the balloon evacuation in the sitting position. And also, balloon evacuation should be done in a private setting.…”

Section: Position Of the Patient During Defecationmentioning

confidence: 99%