A 76-year-old woman with a medical history signiﬁcant for hypertension, diabetes, and multiple cerebral infarcts presented with a 3day history of progressive abdominal pain and tarry stools
Amy P. Oberhelman, MD
Edward Y. Lee, MD, MPH
, from the Mallinckrodt Institute of Radiology, Washington
University Medical Center, St. Louis, MO.
A 76-year-old woman with a medical history significant for
hypertension, diabetes, and multiple cerebral infarcts presented
with a 3day history of progressive abdominal pain and tarry stools.
Significant examination and laboratory findings included a
diffusely tender abdomen, elevated white blood cell count
(19,000/µL), and a positive fecal occult blood test. All other
examination and laboratory findings were within normal limits.
Mesenteric ischemia secondary to superior mesenteric artery
An abdominal radiograph on admission revealed slightly distended
small bowel loops containing air-fluid levels consistent with early
distal small bowel obstruction or focal ileus secondary to an
intra-abdominal inflammatory process (not shown).
Contrast-enhanced computed tomography (CT) of the abdomen showed
a partial filling defect of the SMA (Figures 1 and 2). A slight
distention of one of the small bowel loops with surrounding
mesenteric fat infiltration was also noted, most likely
representing ischemic bowel (Figure 3). There was no evidence of
pneumatosis intestinalis, portal venous gas, or
A selective catheter angiogram of the SMA revealed at least
three filling defects. The first filling defect, located in the
proximal SMA, was nonocclusive (Figure 4). Another nonocclusive
filling defect was located in the distal-most branch of the right
lower aspect of the SMA. The third filling defect was located in
the left aspect of the SMA and was occlusive.
The patient underwent exploratory laparotomy, which revealed
nonocclusive thrombus in the proximal SMA. The patient eventually
underwent SMA thromboembolectomy and segmental resection and
reanastomosis of the distal ileum.
Mesenteric ischemia accounts for approximately 0.1% of hospital
admissions and is found in 1% of patients with acute abdomen.
The nonspecificity of clinical signs and symptoms associated with
the early stages of ischemia often delays diagnosis until extensive
and irreversible bowel infarction has occurred. These delays in
diagnosis substantially contribute to the poor prognosis associated
with this disorder, with mortality rates exceeding 60%.
Mesenteric ischemia most often results from SMA embolization or
thrombosis, and, less commonly, venous occlusion or nonocclusive
processes. Embo-lization of the SMA accounts for nearly 50% of
cases, with thrombosis responsible for another 25% of cases.
Early identification of the disorder requires a high index of
suspicion in patients with significant risk factors, such as
congestive heart failure, cardiac dysrythmias, recent myocardial
infarction, severe valvular cardiac disease, generalized
atherosclerosis, intra-abdominal malignancy, previous arterial
emboli, pancreatitis, or hemorrhage.
In terms of clinical presentation, mesenteric ischemia may
present with increasing abdominal pain and decompensation over a
period of hours or with symptom progression over several days.
Abdom-inal pain is the most common symptom. It occurs in >75% of
patients and varies in severity, nature, and location.
Pain is often associated with vomiting, diarrhea, diaphoresis, and
Unfortunately, despite these symptoms, clinical examination of the
abdomen is often benign. Evidence of generalized or localized
peritonitis may not be evident until infarction has occurred. Other
late signs include hematochezia, hematoemesis, positive fecal
occult blood testing, massive abdominal distention, back pain,
hypotension, and shock.
Leukocytosis (>15,000 cells/µL) occurs in approximately 75% of
patients, and more than half of patients will present with
Findings on plain abdominal radiographs are normal or
nonspecific in >25% of cases of early mesenteric ischemia.
Subtle signs include adynamic ileus, distended and air-filled loops
of bowel, small intestine "thumb-printing," and bowel-wall
thickening from submucosal edema or hemorrhage.
Advanced stages of ischemia are associated with pneumatosis of the
bowel wall and evidence of portal vein gas.
CT can be used to detect ischemic changes, such as circumferential
bowel-wall thickening, mesenteric stranding of fluid, pneumatosis,
and submucosal hemorrhage, or edema.
CT may also determine the cause of the ischemia by allowing
evaluation of the mesenteric vasculature for embolus, thrombus,
atherosclerosis, vasoconstriction, compression, trauma, or invasion
The definitive diagnostic study for mesenteric ischemia is
angiography. Approximately 90% of patients with acute mesenteric
ischemia who undergo angiography before the onset of peritoneal
signs survive, demonstrating the value of angiography and early
In cases of SMA embolization, the classic "meniscus sign" is often
visualized at the point of occlusion. Most emboli lodge 3 to 10 cm
into the tapered segment of the SMA.
Thrombosis is most often identified with a flush aortogram.
Although complete occlusion of the SMA usually occurs within 1 to 2
cm of its origin, collateral pathways almost always fill the vessel
distal to the obstruction.
In terms of treatment, small peripheral lesions may not require
immediate surgery and may respond to medical therapy.
Anticoagulation is advocated in patients suspected of having SMA
thrombosis, and thrombolytic therapy may benefit selected patients
with early diagnosis of SMA embolus unassociated with bowel
In most cases, surgical exploration is emergently performed to
restore intestinal arterial flow and resect irreparably damaged
Due to the nonspecific clinical signs and symptoms of the early
states of mesenteric ischemia secondary to superior mesenteric
artery thrombus, the correct diagnosis is often delayed until
extensive and irreversible bowel infarction has occurred. Early
diagnosis with CT and angiography can help to make an early
diagnosis and to decrease the morbidity and mortality associated
with this disorder.
The authors thank Dr. Huy Tran, St. Vincent's Doctor's Hospital,
Little Rock, AR and Dr. Michael D. Darcy, Mallinckrodt Institute of
Radiology, Washington University Medical Center, St. Louis, MO for
supplying the images in this report.