highly acidic foods) may help maintain overall gas-
trointestinal health. High-fiber foods often worsen
the symptoms of ulcerative colitis and Crohn’s dis-
ease that involves the colon. People who have IBD
generally need NUTRITIONAL SUPPLEMENTS, particu-
larly folic acid (folate) and iron, to offset nutritional
deficiencies that result from MALABSORPTION.
Smoking exacerbates Crohn’s disease. In addition
to irritating the gastrointestinal tract, alcohol inter-
acts with many of the medications to treat IBD.
See also ANTIBODY; APPENDICITIS; AUTOIMMUNE DIS-
ORDERS; CANCER PREVENTION; CANCER RISK FACTORS;
CELIAC DISEASE; COLITIS; DIVERTICULAR DISEASE;
ENDOSCOPY; GASTROENTERITIS; GASTROINTESTINAL BLEED-
ING; ILEUS; IRRITABLE BOWEL SYNDROME(IBS); KAPOSI’S
SARCOMA; NUTRITIONAL DEFICIENCY; NUTRITIONAL NEEDS;
PERITONITIS.
intestinal adhesions Areas of tissue that fuse
together when SCARtissue extends into normal tis-
sue. Intestinal adhesions are most common in peo-
ple who have had abdominal surgery (particularly
multiple operations) though also may form with
ENDOMETRIOSIS, INFLAMMATORY BOWEL DISEASE(IBD),
CELIAC DISEASE, and other circumstances in which
there is damage to the abdominal tissues that gen-
erates scar tissue. Intestinal adhesions may cause
abdominal discomfort during certain movements
or activities or can become extensive enough to
create partial or complete intestinal obstruction
(ILEUS). Intestinal adhesions that interfere with
digestive functions usually require surgery to clear
away the scar tissue. Inherent in this treatment
approach, however, is the risk for additional intes-
tinal adhesions to form as a result of the scar tissue
that develops during HEALING. Most intestinal adhe-
sions do not cause functional problems. Surgeons
typically remove any intestinal adhesions that are
present whenever they perform other surgeries.
See also SURGERY BENEFIT AND RISK ASSESSMENT.
intestinal obstruction See ILEUS.
intestinal polyp A fleshy growth, also called an
intestinal polypoidADENOMA, that grows from the
mucous membrane lining of the COLONor RECTUM.
There are two common types of intestinal polyps,
neoplastic adenomas and hyperplastic adenomas,
both of which grow almost exclusively in the
colon. Neoplastic adenomas are neoplastic (abnor-
mal growths that have no purpose or function in
the body) and have the potential to turn malig-
nant. Hyperplastic adenomas are not neoplastic
and have no malignant potential.
Adenomas of either type arise from the epithe-
lial cells, which make up the surfaces of mem-
branes as well as the SKIN. Epithelial cells
continuously renew themselves to replace worn
and damaged epithelial tissues. Protein messen-
gers tell healthy cells when to stop growing, con-
taining the structures they form. When this
regulatory mechanism goes awry cells continue to
grow, forming abnormal structures such as adeno-
mas. Adenomas, in the intestinal tract as well as
elsewhere in the body, become more common
with increasing age. Various circumstances con-
verge that permit ADENOMA-TO-ADENOCARCINOMA
transition. Though only a small percentage of
intestinal polyps become cancerous, more than 95
percent of COLORECTAL CANCERevolves from intes-
tinal polyps. Typically this transition takes 5 to 10
years or longer, during which biopsy can detect
the changes in the cells (DYSPLASIA). Cancer experts
recommend removal of all intestinal polyps to pre-
vent this evolution. COLONOSCOPYis the most com-
mon method for detecting and removing intestinal
polyps.
See also ACTINIC KERATOSIS; AGING, GASTROINTESTI-
NAL CHANGES THAT OCCUR WITH; CANCER PREVENTION;
CANCER RISK FACTORS; FAMILIAL ADENOMATOUS POLY-
POSIS(FAP).intussusception A circumstance in which one
portion of the intestine slides over another in tele-
scopic fashion, creating an intestinal obstruction
(ILEUS). Intussusception typically occurs in infants
between the ages of 3 and 10 months, though can
develop in children up to age six years. It is three
times more common in boys than girls.Intussusception is a life-threatening
emergency that requires immediate
treatment.Symptoms include waves (paroxysms) of PAIN
that at first appear to be colicky. Within 12 hours,
however, the course shifts sharply from that of
colic. DIARRHEA and VOMITINGdevelop, and pain64 The Gastrointestinal System