• Blood tests : Elevated sedimentation rate (ESR) and C-reactive protein. In severe form of Crohn's Disease., findings include hypoalbuminemia, anemia, and leukocytosis.
• X-ray abdomen and Contrast studies may show thickened folds, aphthous ulcerations, strictures, fistulas, inflammatory masses, and abscesses.
• Endoscopy shows rectal sparing, aphthous ulcerations, fistulas, and skip lesions. It is useful for biopsy of mass lesions or strictures, or for visualization of filling defects seen on barium enema. Upper endoscopy is useful in diagnosing gastroduodenal involvement in patients with upper tract symptoms.
• Sigmoidoscopy : It examines lower third of the large intestine i.e. the rectum and Sigmoid colon
• Colonoscopy : It allows examination and biopsy of the terminal ileum. Ileal or colonic strictures may be dilated with balloons introduced through the colonoscope.
• CT scan : It can help identify perianal disease, adenopathy, abscesses, fistulas, and sinus tracts.
• Magnetic resonance imaging (MRI):This may prove superior for demonstrating pelvic lesions such as ischiorectal abscesses.