Alteration of the Mechanisms of Anorectal Expulsion
Dyssynergia of the pelvic floor: the term, defined by the Rome Criteria, provides as a symptomatologic expression of the entity characterized by straining during evacuation, a sensation of incomplete evacuation, or the recourse to fingering in at least 25 percent of evacuation actions. It has also been defined as abdomino-pelvic dyssynergia and can be identified through manometry, electromyography, or defecography as the incapacity of the muscles of the pelvic floor to relax during the act of defecation (14),(17).
Dyschezia (from the Greek word meaning difficult defecation) indicates symptoms related to the difficulty in expelling stools without implying any demonstration of one or more related physiopathologic correlations.
Rectal constipation is identified by the segmental transit time of the large intestine which shows a transit slowing in the rectum and not in the proximal tracts (5).
Anismus indicates a condition, initially described in young women, which is characterized by difficulty in expelling spherical objects that had been introduced into the rectum (14). Subsequently the meaning of the term was broadened to indicate expulsion difficulty of both female and male patients of all ages. It is frequently used as a synonym of abdomino-pelvic dyssynergia.
Functional megarectum identifies the presence of a rectal ampulla dilated and distended by stool in the absence of organic lesion. This form of constipation with rectal stasis is one of the forms of rectal constipation.
Constipation due to a lack of evacuative stimulus: the diminished or absent perception of the stimulus to evacuate can delay evacuative action and reduce the frequency of the alvus (6).
cindicates a form of constipation with a demonstrated transit slowing in the recto-sigma and/or with the clinical presentation of dyschezia (8).
Constipation caused by descent of the pelvic floor defines the difficulty in expelling stools due to an excessive lowering of the pelvic floor while pushing forcefully, or due to the lowering of the pelvic floor beyond the bi-ischiatic line at rest (1),(8).
It is not always possible to distinguish between the constipation due to slow colonic transit and the constipation due to altered machanisms of anorectal expulsion. So if one refers to the diagnostic Rome Criteria, 96.5 percent of patients with chronic constipation satisfy criteria for dyschezia (23), and without a doubt patients with constipation with alterations of both colonic transit and mechanisms of anorectal expulsion can be frequently found.
Rectocolonic constipation indicates form of constipation with stasis of the content evidenced both at the level of the colon, usually the left, and of the rectum.
Functional megarectum-megacolon are characterized by a dilatation of the rectum and of more proximal tracts of the colon with stasis of the stool in the enlarged parts.