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short bowel syndrome Reduction in the struc-
tural or functional length of the SMALL INTESTINE
that results in MALABSORPTION, chronic DIARRHEA,
and other disturbances of digestion. MALNUTRITION
is a common consequence. Short bowel syndrome
most often results from surgery that removes seg-
ments of the small intestine as treatment for
Crohn’s disease, DIVERTICULAR DISEASE, cancers of
the small intestine, traumatic injury, and other
conditions that irreparably damage the small
intestine. Short bowel syndrome was a common
complication of a weight loss operation,
jejunoileal bypass, that surgeons no longer per-
form. Functional short bowel syndrome also may
develop following severe COLITIS (such as may
occur with ESCHERICHIA COLIO157:H7 INFECTION) or
radiation GASTROENTERITIS.
Treatment options for short bowel syndrome
attempt to manage symptoms such as diarrhea as
well as to meet NUTRITIONAL NEEDS. Most people
who develop short bowel syndrome require PAR-
ENTERAL NUTRITION, a form of long-term intravenous
feeding. Surgical options include operations to
extend the remaining small intestine through var-
ious procedures and SMALL BOWEL TRANSPLANTATION
or multivisceral transplantation (typically small
bowel and LIVER or small bowel, liver, STOMACH,
and PANCREAS). The extensive presence of lym-
phatic tissue in the gastrointestinal tract creates
IMMUNE RESPONSEchallenges with transplantation.
Liver and biliary dysfunctions (notably
CHOLESTASIS) are common complications of short
bowel syndrome, as the JEJUNUMand ILEUMpro-
duce a number of DIGESTIVE HORMONESthat help to
regulate liver activity and BILErelease. When these
segments of the small intestine are missing or no
longer functional, the body has no secondary sys-
tems to synthesize these hormones. Long-term

total parenteral nutrition exacerbates liver and bil-

iary dysfunctions. These factors tend to lead to

LIVER FAILURE. Research directions for solutions to

the challenges of short bowel syndrome therapies

include explorations in IMMUNOTHERAPY (with a

focus on suppressing the immune response in

transplantation), pharmacotherapy (with a focus

on supplemental hormones), and surgical meth-

ods that might improve small bowel function

without transplantation.

See also CYSTIC FIBROSIS; GUT-ASSOCIATED LYMPHOID

TISSUE(GALT); FOOD-BORNE ILLNESSES; INFLAMMATORY

BOWEL DISEASE (IBD); MUCOSA-ASSOCIATED LYMPHOID

TISSUE(MALT); RADIATION THERAPY.

sitz bath A small basin designed to accommo-

date the perineal and rectal areas, with the water

level only to the hips. Numerous commercial

products are available for ease of use at home.

Placing a shallow amount of water in the regular

bathtub accomplishes the same objective, which is

to soothe irritated tissues caused by, for example,

EPISIOTOMYincision, ANAL FISSURE, and HEMORRHOIDS.

The water may contain medications or herbs for

additional therapeutic effect.

See also MEDICINAL HERBS AND BOTANICALS.

small bowel transplantation Replacement of a

diseased SMALL INTESTINE with a cadaver donor

small intestine. Small bowel transplantation is a

final treatment option forSHORT BOWEL SYNDROME

or other circumstances in which there is total loss

of small intestine structure or function. The gas-

troenterologist may consider small bowel trans-

plantation when all other treatments, including

total PARENTERAL NUTRITION, have failed. Small

bowel transplantation is an extraordinarily com-

plex procedure. The complication rate is high, and

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