Gastrointestinal Bleeding Answers 313mesenteric ischemia, but the specificity is low, ranging from 42% to 87%.
Elevated serum lactate may best be used as a predictor of mortality. Some
studies suggest that the presence of an unexplained acidosis should prompt a
search for reversible causes of mesenteric ischemia. (e)Intraluminal barium
contrast studies are contraindicated with suspected mesenteric ischemia
because residual contrast material can limit visualization of the vasculature
during diagnostic angiography.
285.The answer is e.(Townsend et al, p 1256.)Angiodysplasias,also
known as arteriovenous malformations,are small ectatic blood vessels in
the submucosa of the GI tract. More than half of angiodysplasias are located
on the right side of the colon.
(a)Angiodysplasias are responsible for 3% to 20% of acute lower GI
bleeds.(b)Although angiodysplasia accounts for the most common cause
of lower GI bleeding in younger patients, its incidence overall increases with
age over 50 years. (c)While angiography may identify angiodysplasias,
colonoscopy remains the most sensitive diagnostic modality. On colonoscopy,
angiodysplasias appear as red, flat lesions, measuring approximately 2 to 20 mm
in diameter. (d)Angiodysplasias are associated with many medical problems,
including end-stage renal disease, aortic stenosis, and von Willebrand disease,
among others.
286.The answer is b.(Rosen, pp 1241-1244.)The most common cause of
upper GI bleeds in adults is peptic ulcer diseaseaccounting for approxi-
mately 45% of the cases. Hematemesis is the presentation in approximately
50% of patients with upper GI bleeds. The appearance of coffee-grounds in
the stomach is caused by the conversion of hemoglobin to hematin or other
pigments by hydrochloric acid in the stomach.
(a)Varices account for 10%, (c)erosions 23%, (d)Mallory-Weiss tear
7%, and (e)esophagitis 6%.
287.The answer is e.(Rosen, p 1385.)The patient most likely has an
esophageal perforation,a serious, life-threatening complication of endoscopy
that must be identified and treated quickly. Although sometimes reported
as a result of forceful vomiting (eg, Boerhaave syndrome), the most common
cause is iatrogenic. These usually occur as a complication of GI procedures,
including upper endoscopy, dilation, sclerotherapy, and even NG tube placement
or endotracheal intubation. The signs and symptoms may include chest pain
near the rupture site, fever, respiratory distress, hoarseness, or dysphagia. Most