This is a medical question of type : exams and tests 
 How to diagnose Crohn's Disease ? 
 A health care provider diagnoses Crohn's disease with the following:
                
- medical and family history  - physical exam  - lab tests  - upper GI series  - computerized tomography (CT) scan  - intestinal endoscopy
                
The health care provider may perform a series of medical tests to rule out other bowel diseases, such as irritable bowel syndrome, ulcerative colitis, or celiac disease, that cause symptoms similar to those of Crohn's disease.
                
Medical and Family History
                
Taking a medical and family history can help a health care provider diagnose Crohn's disease and understand a patient's symptoms. He or she will ask the patient to describe his or her
                
- family history  - symptoms  - current and past medical conditions  - current medications
                
Physical Exam
                
A physical exam may help diagnose Crohn's disease. During a physical exam, the health care provider most often
                
- checks for abdominal distension, or swelling  - listens to sounds within the abdomen using a stethoscope  - taps on the abdomen to check for tenderness and pain and establish if the liver or spleen is abnormal or enlarged
                
Lab Tests
                
A health care provider may order lab tests, including blood and stool tests.
                
Blood tests. A blood test involves drawing blood at a health care provider's office or a lab. A lab technologist will analyze the blood sample. A health care provider may use blood tests to look for changes in
                
- red blood cells. When red blood cells are fewer or smaller than normal, a patient may have anemia.  - white blood cells. When the white blood cell count is higher than normal, a person may have inflammation or infection somewhere in his or her body.
                
Stool tests. A stool test is the analysis of a sample of stool. A health care provider will give the patient a container for catching and storing the stool at home. The patient returns the sample to the health care provider or to a lab. A lab technologist will analyze the stool sample. Health care providers commonly order stool tests to rule out other causes of GI diseases.
                
Upper Gastrointestinal Series
                
An upper GI series, also called a barium swallow, uses x-rays and fluoroscopy to help diagnose problems of the upper GI tract. Fluoroscopy is a form of x-ray that makes it possible to see the internal organs and their motion on a video monitor. 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 ask their health care provider about how 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 a health care provider can see the shape of these organs 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 causes white or light-colored stools. A health care provider will give the patient specific instructions about eating and drinking after the test.
                
Computerized Tomography Scan
                
Computerized tomography scans use a combination of x-rays and computer technology to create images. For a CT scan, a health care provider may give the patient a solution to drink and an injection of a special dye, called contrast medium. CT scans require the patient to lie on a table that slides into a tunnel-shaped device where the x-rays are taken. An x-ray technician performs the procedure in an outpatient center or a hospital, and a radiologist interprets the images. The patient does not need anesthesia. CT scans can diagnose both Crohn's disease and the complications seen with the disease.
                
Intestinal Endoscopy
                
Intestinal endoscopies are the most accurate methods for diagnosing Crohn's disease and ruling out other possible conditions, such as ulcerative colitis, diverticular disease, or cancer. Intestinal endoscopies include
                
- upper GI endoscopy and enteroscopy  - capsule endoscopy  - colonoscopy
                
Upper GI endoscopy and enteroscopy. An upper GI endoscopy is a procedure that uses an endoscopea small, flexible tube with a lightto directly visualize the lining of the upper GI tract. A health care provider performs the procedure at a hospital or an outpatient center. A nurse or technician may give the patient a liquid anesthetic to gargle or will spray the anesthetic on the back of a patient's throat. The anesthetic numbs the throat and calms the gag reflex. The nurse or technician will then place an intravenous (IV) needle in the person's arm or hand to provide a sedative. The health care provider carefully feeds the endoscope down the patient's esophagus and into the stomach. A small camera on the endoscope sends a video image to a monitor, allowing close examination of the GI tract.
                
During an enteroscopy, the health care provider examines the small intestine with a special, longer endoscope. The health care provider carefully feeds the endoscope into the small intestine using one of the following procedures:
                
- push enteroscopy, which uses a long endoscope to examine the upper portion of the small intestine  - single- or double-balloon enteroscopy, which use small balloons to help move the endoscope into the small intestine  - spiral enteroscopy, which uses a tube attached to an endocope that acts as a cork screw to move the instrument into the small intestine
                
The procedure most often takes between 15 and 60 minutes. The endoscope does not interfere with the patient's breathing, and many patients fall asleep during the procedure.
                
Capsule endoscopy. Although this procedure can examine the entire digestive tract, health care providers use it mostly to examine the small intestine. The patient swallows a capsule containing a tiny camera. As the capsule passes through the GI tract, the camera will record and transmit images to a small receiver device worn by the patient. When the recording is done, the health care provider downloads the images and reviews them on a video monitor. The camera capsule leaves the patient's body during a bowel movement and is safely flushed down the toilet.
                
Colonoscopy. Colonoscopy is a test that uses a long, flexible, narrow tube with a light and tiny camera on one end, called a colonoscope or scope, to look inside a patient's rectum and entire colon. In most cases, light anesthesia and pain medication help patients relax for the test. The medical staff will monitor a patient's vital signs and try to make him or her as comfortable as possible. A nurse or technician will place an IV needle in a vein in the patient's arm or hand to give anesthesia.
                
For the test, the patient will lie on a table or stretcher while the gastroenterologist inserts a colonoscope into the patient's anus and slowly guides it through the rectum and into the colon. The scope inflates the large intestine with air to give the gastroenterologist a better view. The camera sends a video image of the intestinal lining to a monitor, allowing the gastroenterologist to examine the tissues lining the colon and rectum. The gastroenterologist may move the patient several times and adjust the scope for better viewing. Once the scope has reached the opening to the small intestine, the gastroenterologist slowly withdraws it and examines the lining of the colon and rectum again.
                
A colonoscopy can show inflamed and swollen tissue, ulcers, and abnormal growths such as polypsextra pieces of tissue that grow on the inner lining of the intestine. If the gastroenterologist suspects Crohn's disease, he or she will biopsy the patient's colon and rectum. A biopsy is a procedure that involves taking small pieces of tissue for examination with a microscope.
                
A health care provider will give patients written bowel prep instructions to follow at home before the test. The health care provider will also give patients information about how to care for themselves following the procedure.