This is a medical question of type : exams and tests 
 How to diagnose Gastritis ? 
 A health care provider diagnoses gastritis based on the following:
                
- medical history  - physical exam  - upper GI endoscopy  - other tests
                
Medical History
                
Taking a medical history may help the health care provider diagnose gastritis. He or she will ask the patient to provide a medical history. The history may include questions about chronic symptoms and travel to developing countries.
                
Physical Exam
                
A physical exam may help diagnose gastritis. During a physical exam, a health care provider usually
                
- examines a patient's body  - uses a stethoscope to listen to sounds in the abdomen  - taps on the abdomen checking for tenderness or pain
                
Upper Gastrointestinal Endoscopy
                
Upper GI endoscopy is a procedure that uses an endoscopea small, flexible camera with a lightto see the upper GI tract. A health care provider performs the test at a hospital or an outpatient center. The health care provider carefully feeds the endoscope down the esophagus and into the stomach and duodenum. The small camera built into the endoscope transmits a video image to a monitor, allowing close examination of the GI lining. A health care provider may give a patient a liquid anesthetic to gargle or may spray anesthetic on the back of the patient's throat before inserting the endoscope. A health care provider will place an intravenous (IV) needle in a vein in the arm to administer sedation. Sedatives help patients stay relaxed and comfortable. The test may show signs of inflammation or erosions in the stomach lining.
                
The health care provider can use tiny tools passed through the endoscope to perform biopsies. A biopsy is a procedure that involves taking a piece of tissue for examination with a microscope by a pathologista doctor who specializes in examining tissues to diagnose diseases. A health care provider may use the biopsy to diagnose gastritis, find the cause of gastritis, and find out if chronic gastritis has progressed to atrophic gastritis. More information is provided in the NIDDK health topic, Upper GI Endoscopy.
                
Other Tests
                
A health care provider may have a patient complete other tests to identify the cause of gastritis or any complications. These tests may include the following:
                
- Upper GI series. Upper GI series is an x-ray exam that provides a look at the shape of the upper GI tract. An x-ray technician performs this test at a hospital or an outpatient center, and a radiologista doctor who specializes in medical imaginginterprets the images. This test does not require anesthesia. A patient should not eat or drink before the procedure, as directed by the health care provider. Patients should check with their health care provider about what to do to prepare for an upper GI series. During the procedure, the patient will stand or sit in front of an x-ray machine and drink barium, a chalky liquid. Barium coats the esophagus, stomach, and small intestine so the radiologist and health care provider can see these organs' shapes more clearly on x-rays. A patient may experience bloating and nausea for a short time after the test. For several days afterward, barium liquid in the GI tract may cause white or light-colored stools. A health care provider will give the patient specific instructions about eating and drinking after the test. More information is provided in the NIDDK health topic, Upper GI Series.  - Blood tests. A health care provider may use blood tests to check for anemia or H. pylori. A health care provider draws a blood sample during an office visit or at a commercial facility and sends the sample to a lab for analysis.  - Stool test. A health care provider may use a stool test to check for blood in the stool, another sign of bleeding in the stomach, and for H. pylori infection. A stool test is an analysis of a sample of stool. The health care provider will give the patient a container for catching and storing the stool. The patient returns the sample to the health care provider or a commercial facility that will send the sample to a lab for analysis.  - Urea breath test. A health care provider may use a urea breath test to check for H. pylori infection. The patient swallows a capsule, liquid, or pudding that contains ureaa waste product the body produces as it breaks down protein. The urea is labeled with a special carbon atom. If H. pylori are present, the bacteria will convert the urea into carbon dioxide. After a few minutes, the patient breathes into a container, exhaling carbon dioxide. A nurse or technician will perform this test at a health care provider's office or a commercial facility and send the samples to a lab. If the test detects the labeled carbon atoms in the exhaled breath, the health care provider will confirm an H. pylori infection in the GI tract.