Constipation slow-transit

Constipation can be due to primary and secondary causes (Table 18-1). Primary or idiopathic constipation is typified by normal-transit constipation, slow-transit constipation, and dyssynergic defecation. In the normal-transit type, colonic motility is unchanged and patients tend to experience hard stools despite normal movements. In the slow-transit type, motility is decreased leading to infrequent harder, drier stools. In dyssynergic defecation (also known as pelvic floor dysfunction), patients have lost the ability to relax the anal sphincter while coordinating muscle contractions of the pelvic floor. Some causes of secondary constipation are listed in Table 18-1. 

Slow-transit constipation (includes motility disorders)... 

Slow-transit constipation can be treated with chronic administration of osmotic laxatives. Tegaserod maleate 6 mg orally twice daily is an acceptable treatment. Senna, bisacodyl, and other stimulants should be used only when the others fail to deliver the desired effect. 

J. M. B. H., Abnormalities of upper gut motility in patients with slow-transit constipation, Eur. J. Gastroenterol. Hepatol. 1999, 3 3, 701-708. 

The first observation in this field was made by Heaton et al In normal-weight women with gallstones but no other obvious risk factors, the Bristol investigators found that, compared with age- and sex-matched controls, the gallstone carriers had almost a 20-h longer whole gut transit time. Despite this, their mean faecal wet weight was only half that of the controls. Put another way, the women with gallstones had slow transit constipation. 

Constipation is associated with slow transit of faecal material through the large intestine and increased fluid absorption, resulting in hard, dry faeces. 

Digestive system g agonists decrease secretion of stomach acid, reduce gastric motility, and prolong gastric emptying. Pancreatic, biliary, and intestinal secretions are reduced. Intestinal transit is also slowed. Peristaltic movements are reduced, but tone is increased, sometimes causing spasm. As a result, constipation is a frequent problem with opioid use. Bile duct pressure is also increased by opioids. 

Constipation may be caused by slow intestinal transition, pelvic floor dysfunction, bowel dysfunction like irritable Bowel syndrome and tumours, but can also be secondary to other diseases and life conditions. Many medicines cause constipation, for example opiates, calcium channel blockers and drugs with anticholinergic effects, e.g. antidepressants. 

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