312 Emergency Medicine
embolus,which accounts for 50% of cases. The classic finding is “pain out
of proportion to examination findings,” that is, a patient complains of severe
pain but is not particularly tender on examination. A high degree of suspicion
for mesenteric ischemia in an elderly patient with abdominal pain is warranted.
(a)Perforated gastric ulcer presents with acute onset of severe epigastric
pain and bleeding, generally in someone with PUD. (b)Diverticulitis presents
as LLQ pain that is usually described as dull and constant. (c)Acute chole-
cystitis occurs with an obstruction of the cystic duct with gallstones and is
often accompanied by fever, chills, nausea, and a positive Murphy sign. It
is the most common surgical emergency in elderly patients. (e)The classic
triad for sigmoid volvulus includes abdominal pain, abdominal distention,
and constipation. Nausea and vomiting are often present, and diagnosis
can be made on plain radiograph in 80% of cases.
284.The answer is d.(Rosen, pp 1447-1448.)Angiographyremains the
“gold standard” in the diagnosis of mesenteric ischemia.Unlike any other
diagnostic tools, it is capable of both diagnosing and treatingthe problem. It is
capable of identifying all four types of acute mesenteric ischemia: (1) arterial
embolus, (2) arterial or (3) venous thrombosis, and, under most circumstances,
(4) nonocclusive mesenteric ischemia. Angiography should be obtained with-
out delay when the diagnosis is suspected.
With the exception of angiography, the results of all other studies are
most useful in ruling out other diagnoses or finding out baseline levels.
Abdominal radiographs (b)should be performed on any patient with
suspectedmesenteric ischemia to rule out bowel obstruction or free air.
However, in the early stages, plain radiographs are most often normal in
patients with mesenteric ischemia and should not be used to rule out this
entity. Positive findings include intraluminal gas or gas in the portal venous
system, usually coincide with the development of necrotic bowel, and signify
a grim prognosis. (c)Because of its availability, speed, and improved quality,
CT is often used in the ED for assessing abdominal pain of unclear etiology
in high-risk patients. CT may identify indirect signs of ischemia—including
edema of the bowel wall or mesentery, abnormal gas patterns, intramural
gas, and ascites. Occasionally, CT may accurately identify direct evidence of
mesenteric venous thrombosis. As with abdominal radiographs, many patients
may have normal or nonspecific findings on CT, so it cannot be used to rule
out the diagnosis of mesenteric ischemia. While a few studies have found
CT to be as sensitive as angiography, it is not currently the study of choice.
(a)The sensitivity of serum lactate is high, nearly 100%, in the presence of