maging studies
Obtain flat and upright abdominal radiographs if the patient experiences bloating, severe pain, or obstructive symptoms or if the clinical picture suggests perforation.
Procedures
Consider performing the following procedures when a stool examination is nondiagnostic, especially in immunocompromised patients:
Sigmoidoscopy/colonoscopy with biopsy
EGD with duodenal aspirate and biopsy
In patients with bloody diarrhea, sigmoidoscopy can be useful in diagnosing inflammatory bowel disease, antibiotic-associated diarrhea, shigellosis, and amebic dysentery.