Encyclopedia of Health and Medicine

T–Z
toxic megacolon A serious condition in which a
loss of MUSCLE tone in the lower COLON (typically
the sigmoid colon) causes the preceding segment
of colon to greatly enlarge (dilate). Air accumulates
in the dilated bowel, increasing the pressure.
Without prompt treatment intestinal perforation
(rupture) is highly likely, with consequential PERI-
TONITIS.
Toxic megacolon is a potentially lifethreatening
condition that requires
emergency medical treatment and
often surgery.
Toxic megacolon is usually a complication of
inflammatory conditions affecting the gastrointestinal
tract, such as INFLAMMATORY BOWEL DISEASE
(IBD) or INFECTION (COLITIS). The congenital disorder
HIRSCHSPRUNG’S DISEASE, in which the lower colon
lacks nerves, can cause toxic megacolon in a newborn
infant.
Symptoms and Diagnostic Path
A person who has toxic megacolon is very sick.
Usually there is FEVER along with ABDOMINAL DIS-
TENTION, rigidity, and PAIN. REBOUND TENDERNESS and
absence of BOWEL SOUNDS are common findings.
The person may be in SEPTICEMIA (septic SHOCK),
indicating PERITONITIS. The doctor often can make
the diagnosis with an abdominal X-RAY that shows
the dilated colon.
Treatment Options and Outlook
ANTIBIOTIC MEDICATIONS, CORTICOSTEROID MEDICATIONS,
depending on the cause of the condition, and
intravenous fluids to counter DEHYDRATION may
help stabilize the colon, in combination with positional
changes to attempt to move air (intestinal
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gas) out of the bowel to help relieve the distention.
Surgery to remove the dilated segment of
bowel (colectomy) is often the only treatment to
prevent or treat bowel perforation. The surgeon
then connects the two healthy ends of bowel
together to restore normal bowel function. With
prompt and appropriate treatment, many people
make a full recovery from toxic megacolon. However,
it does present a serious challenge to the
body’s HEALING abilities. As well, any underlying
conditions that precipitated the bowel dilation
may continue to cause symptoms.
Risk Factors and Preventive Measures
The primary risk factor for toxic megacolon is any
condition that causes INFLAMMATION of the colon.
Taking medications to slow gastric motility (such
as to treat DIARRHEA) may contribute to the circumstances
resulting in toxic megacolon. Anyone
who has colitis, GASTROENTERITIS, DIVERTICULAR DIS-
EASE, CELIAC DISEASE, IBD, or other inflammatory
condition affecting the gastrointestinal tract who
experiences symptoms that could suggest toxic
megacolon should see a doctor without delay.
See also ILEUS; SHORT BOWEL SYNDROME.
tube feeding
ulcer
See ENTERAL NUTRITION.
See PEPTIC ULCER DISEASE.
ulcerative colitis See INFLAMMATORY BOWEL DIS-
EASE (IBD).
virtual colonoscopy
See COLONOSCOPY.
vomiting The forceful expulsion of contents
from the STOMACH, also called emesis. The force of
vomiting may also draw digestive material from