The physician’s first job is to find out if the patient actually has ulcerative colitis, or if the symptoms are being caused by something else. A stool sample should be taken to make sure there is no infection. The physician should then look at the bowel through a tube.

This test is called a sigmoidoscopy or colonoscopy, depending on how much of the bowel is examined. The physician can diagnose ulcerative colitis from the appearance of the bowel wall.

Once the doctor is sure that the patient has ulcerative colitis, he or she assesses how severe the disease is, and how much of the bowel is affected, based on the examination and on the patient’s symptoms. This is important, because the kind of treatment to be used depends on the severity of the disease. There are four categories of severity:

Mild. The patient has less than four stools daily, with or without blood. There are no systemic signs of toxicity (meaning that the disease is not causing sickness in the rest of the patient’s body).

Moderate. The patient has more than four stools daily but with little sign of toxicity.
Severe. The patient has more than six bloody stools daily, and has signs of toxicity such as fever, fast heart beat, anemia, or a high erythrocyte sedimentation rate.

Fulminant. The patient has more than 10 bowel movements daily, continuous bleeding, toxicity, and a tender and swollen abdomen.

The doctor also examines how far along the gut the colitis extends. If it is only in the last part, where it can be treated with medications that can be placed into the bowel, it is called left sided colitis . If it goes further, it is called extensive, or pancolitis .

With these two pieces of information, the doctor can start to plan the best way to treat the patient.