A few different tests can be used to diagnose Gastritis, including medical history and physical exam, endoscopy, and biopsy. Your doctor will likely recommend combining these tests to get the most accurate diagnosis. Medical history and physical exam: Your doctor will ask about your symptoms and medical history. They'll also do a physical exam to look for signs of Gastritis. Endoscopy: This test involves inserting a thin, flexible tube with a camera into your stomach. Your doctor will use the camera to look for any inflammation or damage to your stomach lining. Biopsy: Your doctor may also take a small tissue sample from your stomach lining during an endoscopy. This tissue will be tested for H. pylori, a bacteria that can cause Gastritis. Blood test: Your doctor may also order a blood test to look for signs of anemia or inflammation. Imaging tests: In some cases, your doctor may also recommend imaging tests, such as an X-ray or CT scan, to better look at your stomach.