Diagnostic Approach to Gastrointestinal Bleeding in Young Adults

Initial Evaluation and Risk Assessment

The American Gastroenterological Association recommends that patients with iron-deficiency anemia and gastrointestinal bleeding should undergo colonoscopy and upper endoscopy to identify the source of bleeding 1, 2, 6
Patients under 50 years old with a positive fecal occult blood test are unlikely to require evaluation beyond colonoscopy unless they have symptoms of upper gastrointestinal disease 1, 2
The American College of Gastroenterology suggests that patients over 50 years old should undergo colonoscopy due to the higher pre-test probability of colon cancer, while younger patients should undergo colonoscopy or sigmoidoscopy based on clinical characteristics suggestive of disease 5

A complete blood count should be performed to evaluate for anemia 5
Consideration should be given to obtaining a chemistry profile and albumin level based on the patient's symptom pattern 5

Younger patients are more likely to have Dieulafoy's lesion and Crohn's disease as the cause of gastrointestinal bleeding 1, 2, 7
Older patients are more likely to have vascular lesions, which account for up to 40% of all causes of gastrointestinal bleeding 1, 2, 7

Physicians should not attribute a positive fecal occult blood test to low-dose aspirin or anticoagulant medications without further evaluation 6
Lesions commonly missed in the upper gastrointestinal tract include Cameron's erosions, fundic varices, peptic ulcer, angiectasias, Dieulafoy's lesion, and antral vascular ectasia 1, 2, 7
Lesions commonly missed during colonoscopy include angiectasias and neoplasias 1, 2, 7

Confirm positivity of the fecal occult blood test with samples from 3 consecutive bowel movements 3
Evaluate for anemia with a complete blood count 5
If iron-deficiency anemia is present, proceed with colonoscopy (and upper endoscopy if symptoms of upper gastrointestinal disease are present) 1, 2, 6
If no anemia and no symptoms are present, consider observation with re-evaluation if anemia develops 1, 2
If colonoscopy is negative but anemia persists, consider capsule endoscopy for evaluation of the small intestine 1, 2, 6