Jejunoileal bypass

Jejunoileal bypass
Intervention
ICD-9-CM	46.93
MeSH	D007581
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Jejunoileal bypass was a surgical weight-loss procedure performed for the relief of morbid obesity from the 1950s through the 1970s in which all but 30 cm (12 in) to 45 cm (18 in) of the small bowel were detached and set to the side.

Many complications that followed jejunoileal bypass operations were caused by bacterial overgrowth in the excluded blind loop. The arthritis-dermatitis syndrome was one of the common distressing disorders. The pathogenetic mechanism was thought to be an immune-complex-mediated process related to bypass enteritis.

Two variants of jejunoileal anastomosis were developed, the end-to-side and end-to endanastomoses of the proximal jejunum to distal ileum. In both instances an extensive length of small intestine was bypassed, not excised, excluding it from the alimentary stream.

In both these variants a total of only about 45 cm (18 in) of normally absorptive small intestine was retained in the absorptive stream, compared with the normal length of approximately 7 metres (20 ft). In consequence, malabsorption of carbohydrate, protein, lipids, minerals and vitamins inevitably occur. Where the end-to-side technique was used, reflux of bowel content back up the defunctionalized small intestine allowed absorption of some of the refluxed material, resulting in less weight loss initially and greater subsequent weight regain.

Bile is secreted by the liver, enters the upper small intestine by way of the bile duct, and is absorbed in the small intestine. Bile has an important role in fat digestion, emulsifying fat as the first stage in its digestion. Bypassing the major site of bile acid reabsorption in the small intestine therefore further reduces fat and fat-soluble vitamin absorption. As a result, huge amounts of fatty acids, which are normally absorbed in the small intestine, enter the colon, where they cause irritation of the colon wall and the secretion of excessive volumes of water and electrolytes, especially sodium and potassium, leading to diarrhea. This diarrhea is the major patient complaint and has characterized jejunoileal bypass in the minds of patient and physician alike since the procedure was introduced.

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