1. Organic etiology
Mainly includes:
(1) Intestinal organic lesion: intestinal stenosis or obstruction caused by tumor, inflammation or other reasons.
(2) anorectal diseases: rectal prolapse, hemorrhoids, rectocele, puborectal muscle hypertrophy, pubic separation, pelvic floor diseases, etc.
(3) Endocrine or metabolic diseases: diabetes, hypothyroidism, parathyroid diseases, etc.
(4) Systemic diseases: scleroderma, lupus erythematosus, etc.
(5) Nervous system diseases: central brain diseases, apoplexy, multiple sclerosis, spinal cord injury and peripheral neuropathy.
(6) Intestinal smooth muscle or neurogenic lesions.
(7) Colon neuromuscular diseases: pseudointestinal obstruction, Hirschsprung's disease, megarectum, etc.
(8) Neuropsychological disorder.
(9) Drug factors: iron, opioids, antidepressants, anti-Parkinson's drugs, calcium channel antagonists, diuretics and antihistamines.
If constipation does not have the above clear cause, it is called functional constipation. Among people with a secret history of defecation, functional constipation accounts for about 50%.
2. Functional etiology
The etiology of functional constipation is unclear, and its occurrence is related to many factors, including:
(1) Decreased food intake or lack of cellulose or water in food reduced the stimulation to colon movement.
(2) Normal defecation habits are disturbed by intense work, too fast pace of life, changes in the nature and time of work, and mental factors.
(3) Colonic dyskinesia, which is common in irritable bowel syndrome, is caused by spasm of colon and sigmoid colon. In addition to constipation, abdominal pain or bloating also occurs, and some patients may show constipation and diarrhea alternately.
(4) The tension of abdominal muscles and pelvic floor muscles is insufficient, the driving force of defecation is insufficient, and fecal excretion is difficult.
(5) Abuse of laxatives leads to drug dependence and constipation.
(6) The elderly are weak, have too little activity, have difficulty defecating due to intestinal spasm, or have a long colon.
Constipation is mainly divided into two types according to the pathogenesis: slow transit constipation and outlet obstructive constipation.
Slow transit constipation is caused by the weakening of intestinal contraction, which slows down the movement of feces from cecum to rectum, or the uncoordinated movement of left colon. It is most common in young women and occurs around puberty. It shows that the frequency of defecation is reduced (the frequency of defecation per week is less than 1 time), the frequency of defecation is less, the feces are hard and it is difficult to defecate. There was no stool or hard stool during anorectal digital examination, but the function of external anal sphincter contraction and forced defecation was normal. The total gastrointestinal or colonic transit time is prolonged; Lack of evidence of outlet obstruction, such as balloon exhaust test and normal anorectal manometry. Non-surgical treatments such as increasing dietary fiber intake and osmotic laxatives are ineffective. Diabetes, scleroderma complicated with constipation and constipation caused by drugs are mostly slow transmission type.
Outlet obstructive constipation is due to the muscle disharmony of abdomen, anorectum and pelvic floor, which leads to the obstacle of fecal discharge. It is especially common in elderly patients, and many patients are ineffective in routine medical treatment. The outlet obstruction type can have the following manifestations: strenuous defecation, endless feeling or falling feeling, less defecation, defecation or insufficient defecation; There is a large amount of muddy feces in the rectum during anorectal examination, and the external anal sphincter may contract violently when defecating forcibly; The total gastrointestinal or colon transit time is normal, and most markers can remain in the rectum; Anorectal manometry showed that the external sphincter of anus contracted sharply or the sensory threshold of rectal wall was abnormal during forced defecation. Many patients with outlet obstructive constipation also have slow transit constipation.