Constipation can be classified as organic or functional in terms of etiology.
1.Organic etiology
Mainly include
(1) organic lesions of the intestinal canal: tumor, inflammation or other causes of intestinal lumen narrowing or obstruction.
(2) rectal and anal lesions: endorectal prolapse, hemorrhoids, prerectal bulge, puborectal hypertrophy, puborectal separation, pelvic floor disease, etc.
(3) Endocrine or metabolic diseases: diabetes mellitus, hypothyroidism, parathyroid disease, etc.
(4) Systemic diseases: scleroderma, lupus erythematosus, etc.
(5) Neurological disorders: central brain disorders, stroke, multiple sclerosis, spinal cord injury and peripheral neuropathy, etc.
(6) Smooth muscle or neurogenic lesions of the intestinal canal.
(7) Neuromuscular lesions of the colon: pseudo-intestinal obstruction, congenital megacolon, megarectum, etc.
(8) Neuropsychological disorders.
(9) Pharmacologic factors: iron, opioids, antidepressants, antiparkinsonian drugs, calcium channel antagonists, diuretics, and antihistamines.
If constipation does not have a clear etiology such as the above, it is called chronic functional constipation (CFC). In the population with a history of constipation, functional constipation accounts for about 50%.
2.Functional etiology
The cause of functional constipation is not clear, and its occurrence is related to a variety of factors, including.
(1) eating less or food lack of fiber or water, the stimulation of colonic movement is reduced.
(2) Normal bowel habits are disturbed by work stress, fast-paced life, changes in the nature and timing of work, and mental factors.
(3) Due to colonic motility disorder, commonly caused by irritable bowel syndrome, caused by spasm of colon and sigmoid colon, with abdominal pain or bloating in addition to constipation, and some patients may show alternating constipation and diarrhea.
(4) Insufficient tone of the abdominal and pelvic muscles, insufficient pushing force for defecation, and difficulty in expelling feces from the body.
(5) Abuse of laxatives, forming drug dependence, resulting in constipation.
(6) Old age, frailty, low activity, intestinal spasm, resulting in defecation difficulties, or due to the length of the colon.
Constipation is divided into two main categories according to the pathogenesis: slow transmission type constipation and outlet obstruction type constipation.
1. Slow-transmission constipation
It is caused by a weakened contractile movement of the intestine, which slows down the movement of feces from the cecum to the rectum, or by the uncoordinated movement of the left hemicolectomy. It is most common in young women and occurs around puberty, characterized by a reduced number of bowel movements (less than 1 bowel movement per week), less bowel movements, hard stools, and thus difficulty in defecation.
There is no stool or hard stool palpable on anorectal examination, while the external anal sphincter has normal retraction and forceful defecation; prolonged total gastrointestinal or colonic transit time; and lack of evidence of an outlet obstruction type, such as normal balloon expulsion test and anorectal manometry. Non-surgical treatment methods such as increased dietary fiber intake with osmotic laxatives are ineffective. Diabetes, scleroderma combined with constipation and drug-induced constipation is mostly slow transmission type.
2, exit obstruction type constipation
It is due to muscle incoordination in the abdomen, anorectum and pelvic floor that leads to fecal discharge obstruction. It is especially common in elderly patients, many of whom are ineffective with conventional medical treatment. The outlet obstruction type may have the following manifestations: straining to pass stool, a feeling of incompleteness or falling, a small amount of stool, a desire to pass stool or a lack of desire to pass stool; a lot of muddy stool in the rectum on anorectal examination, the external anal sphincter may contract paradoxically during straining to pass stool; the whole gastrointestinal or colonic transit time shows normal, most markers may be retained in the rectum; anorectal manometry shows that the external anal sphincter contracts paradoxically during straining to pass stool contraction or abnormal sensory threshold of the rectal wall, etc. Many patients with outlet obstruction constipation also have a combination of slow-transmission constipation.