This is a medical question of type : exams and tests 
 How to diagnose Ulcerative Colitis ? 
 A health care provider diagnoses ulcerative colitis with the following:
                
- medical and family history  - physical exam  - lab tests  - endoscopies of the large intestine
                
The health care provider may perform a series of medical tests to rule out other bowel disorders, such as irritable bowel syndrome, Crohn's disease, or celiac disease, that may cause symptoms similar to those of ulcerative colitis. Read more about these conditions on the Digestive Disease A-Z list.
                
Medical and Family History
                
Taking a medical and family history can help the health care provider diagnose ulcerative colitis and understand a patient's symptoms. The health care provider will also ask the patient about current and past medical conditions and medications.
                
Physical Exam
                
A physical exam may help diagnose ulcerative colitis. 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
                
Lab Tests
                
A health care provider may order lab tests to help diagnose ulcerative colitis, 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
                
- anemia  - inflammation or infection somewhere in the body  - markers that show ongoing inflammation  - low albumin, or proteincommon in patients with severe ulcerative colitis
                
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, such as infection.
                
Endoscopies of the Large Intestine
                
Endoscopies of the large intestine are the most accurate methods for diagnosing ulcerative colitis and ruling out other possible conditions, such as Crohn's disease, diverticular disease, or cancer. Endoscopies of the large intestine include
                
- colonoscopy  - flexible sigmoidoscopy
                
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 the 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 places an intravenous (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 carefully 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 irritated 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 ulcerative colitis, 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.
                
Flexible sigmoidoscopy. Flexible sigmoidoscopy is a test that uses a flexible, narrow tube with a light and tiny camera on one end, called a sigmoidoscope or scope, to look inside the rectum, the sigmoid colon, and sometimes the descending colon. In most cases, a patient does not need anesthesia.
                
For the test, the patient will lie on a table or stretcher while the health care provider inserts the sigmoidoscope into the patient's anus and slowly guides it through the rectum, the sigmoid colon, and sometimes the descending colon. The scope inflates the large intestine with air to give the health care provider a better view. The camera sends a video image of the intestinal lining to a monitor, allowing the health care provider to examine the tissues lining the sigmoid colon and rectum. The health care provider may ask the patient to move several times and adjust the scope for better viewing. Once the scope reaches the end of the sigmoid colon, the health care provider slowly withdraws it while examining the lining of the colon and rectum again.
                
The health care provider will look for signs of bowel diseases and conditions such as irritated and swollen tissue, ulcers, and polyps.
                
If the health care provider suspects ulcerative colitis, he or she will biopsy the patient's colon and rectum.
                
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.