How is it diagnosed?

A physical examination may reveal an abdominal mass or tenderness, skin rash, swollen joints, or mouth ulcers

Tests to diagnose Crohn's disease include:

Barium enema or upper GI series
Colonoscopy or sigmoidoscopy
Computed tomography (CT scan) of the abdomen
Endoscopy, including capsule endoscopy
Magnetic resonance imaging (MRI) of the abdomen
Enteroscopy
A stool culture may be done to rule out other possible causes of the symptoms.

This disease may also alter the results of the following tests:

Albumin
C-reactive protein
Erythrocyte sedimentation rate
Fecal fat
Hemoglobin
Liver function tests
White blood cell count