A previously healthy 14-year-old boy is brought to the physician because of a 3-month-history of blood in his stool. Prior to the episodes, he was treated with amoxicillin for 7 days for otitis media. The episodes are non-painful and not associated with diarrhea or constipation. Physical examination shows no anal fissures or signs of trauma. Vitals are within normal limits. A photograph of the patient is shown.
Which of the following is the next best step in diagnosis?
Air-contrast enema
Colonoscopy
Meckel scan
Stool culture
Stool toxin test
Upper gastrointestinal series
