Clinical findings
Symptoms of intestinal ischemia vary and can be acute (especially if embolic), subacute, or chronic.Case series report prevalence of clinical findings and provide the best available, yet biased, estimate of the sensitivity of clinical findings. In a series of 58 patients with intestinal ischemia due to mixed causes:
abdominal pain was present in 95% (median of 24 hours duration). The other three patients presented with shock and metabolic acidosis. nausea in 44%
vomiting in 35%
diarrhea in 35%
heart rate > 100 in 33%
rectal bleeding in 16% (not stated if this number also included occult blood – presumably not)
constipation in 7%

Diagnostic heuristics
In the absence of adequate quantitative studies to guide diagnosis, various heuristics help guide diagnosis:

Intestinal ischemia" should be suspected when individuals, especially those at high risk for acute intestinal ischemia, develop severe and persisting abdominal pain that is disproportionate to their abdominal findings"., or simply, pain out of proportion to exam. Regarding intestinal arterial thrombosis or embolism: "early symptoms are present and are relative mild in 50% of cases for three to four days before medical attention is sought". Regarding intestinal arterial thrombosis or embolism: "Any patient with an arrhythmia such as atrial fibrillation who complains of abdominal pain is highly suspected of having embolization to the superior mesenteric artery until proved otherwise." Regarding nonocclusive intestinal ischemia: "Any patient who takes digitalis and diuretics and who complains of abdominal pain must be considered to have nonocclusive ischemia until proved otherwise." Diagnosis
It is difficult to diagnose intestinal ischemia early.
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