Encyclopedia of Health and Medicine

64 The Gastrointestinal System
highly acidic foods) may help maintain overall gastrointestinal
health. High-fiber foods often worsen
the symptoms of ulcerative colitis and Crohn’s disease
that involves the colon. People who have IBD
generally need NUTRITIONAL SUPPLEMENTS, particularly
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 interacts
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 SCAR tissue extends into normal tissue.
Intestinal adhesions are most common in people
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 generates
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 intestinal
adhesions to form as a result of the scar tissue
that develops during HEALING. Most intestinal adhesions
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 polypoid ADENOMA, that grows from the
mucous membrane lining of the COLON or 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 (abnormal
growths that have no purpose or function in
the body) and have the potential to turn malignant.
Hyperplastic adenomas are not neoplastic
and have no malignant potential.
Adenomas of either type arise from the epithelial
cells, which make up the surfaces of membranes
as well as the SKIN. Epithelial cells
continuously renew themselves to replace worn
and damaged epithelial tissues. Protein messengers
tell healthy cells when to stop growing, containing
the structures they form. When this
regulatory mechanism goes awry cells continue to
grow, forming abnormal structures such as adenomas.
Adenomas, in the intestinal tract as well as
elsewhere in the body, become more common
with increasing age. Various circumstances converge
that permit ADENOMA-TO-ADENOCARCINOMA
transition. Though only a small percentage of
intestinal polyps become cancerous, more than 95
percent of COLORECTAL CANCER evolves from intestinal
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 prevent
this evolution. COLONOSCOPY is the most common
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 telescopic
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 VOMITING develop, and pain