Diagnosis of ulcerative colitis is based on evaluation of medical history, family history of the condition and also on certain imaging and laboratory tests.
Medical history
Detailed history of symptoms, age of onset, severity of symptoms, possible triggers for flare ups is obtained. Family history of the condition is enquired as genetics possibly plays a role in inheritance of ulcerative colitis.
Physical examination
The next step is physical examination of the patient. General health, signs of malnutrition are vital for diagnosis and management of ulcerative colitis. The patient is examined for anemia and pain over the abdomen.
Blood tests
These are undertaken to detect abnormalities and presence of inflammation. Routine blood tests help to detect presence of anemia from low red blood cell counts and pale RBCs.
There are two specialised blood tests known as the erythrocyte sedimentation rate (ESR) test and the C reactive protein (CRP) test that are checked in suspected cases of inflammation. These are non specific tests however and may give a positive result if there is an infection present in any part of the body.
Antibody markers and in-depth blood tests
These new blood tests look for antibodies that are produced by the immune system as part of the inflammatory processes. The ones tested include Perinuclear anti-neutrophil antibodies (pANCA) and Anti-Saccharomyces Cerevisiae antibody (ASCA). These antibodies are called biomarkers.
Many patients with ulcerative colitis have the pANCA antibody in their blood while patients with Crohn’s disease are more likely to have ASCA in their blood. However, these antibody tests are not absolute and foolproof. In some cases, patients have neither antibody while sometimes the antibodies may be positive in patients without either disease.
Stool examination
Samples of stools are examined for presence of inflammatory cells, mucus and traces of blood. These indicate presence of an active inflammation in the gut.
Barium enema X rays
A solution of Barium is given to the patient to drink and after an appropriate time an X ray of the abdomen is performed. Since the compound is radio-opaque and shows up on X rays, the outlines of the gut walls may be seen clearly. This may help in diagnosis.
Sigmoidoscopy and Colonoscopy
This is a more confirmatory test that detects and diagnoses ulcerative colitis. A Sigmoidoscopy or Colonoscopy detects the level and extent of the inflammation of the bowel.
It involves inserting a flexible tube containing a light and a camera on its tip via the anus into the gut. This is not a painful procedure and is performed under sedation. It usually takes around 15 minutes to half an hour to complete.
The images of the gut walls are transmitted to a computer from where the physician may get to see the inside walls of the gut.
The sigmoidoscope is only capable of looking at the rectum and lower part of the colon while the colonoscope covers the entire colon up until the ileocecal junction. These tests serve another purpose of ruling out other bowel conditions with similar symptoms including bowel cancers.
Another similar test is the EGD (Esophagogastroduodenoscopy) that uses the same principles to examine the linings of the esophagus, stomach, and duodenum. This is helpful in ruling out Crohn’s disease as this condition may affect the upper gastrointestinal tract as well.
Capsule Enteroscopy uses as small capsule with sensors and a camera that is taken as a pill and that transmits the images from within the gut.
ERCP (Endoscopic retrograde cholangiopancreatography) is another test that examines the bile ducts in the liver and the pancreatic duct. This helps to rule out Primary Sclerosing Cholangitis (PSC) that is seen in some patients with ulcerative colitis.
CT scans
CT scans or Computerized tomography scans may be used to detect complications of ulcerative colitis including abscesses, fistulas, and intestinal blockages. These can also help diagnosing and ruling out bowel cancers.
Other imaging studies
Other imaging studies include CT Enterography, Magnetic Resonance Enterography (MR Enterography), MRI of Pelvis etc. These also give a clearer view of the structures around the gut and the extent of damage caused to the intestines and other organs by the disease.
White Blood Cell scan
A relatively newer test is the Leukocyte scintigraphy or the White Blood Cell scan. During inflammation the WBCs crowd at the sites of inflammation. This test can see where these WBCs gather during flare ups.
For this test a small sample of blood is taken from the arm and the WBCs are then tagged using harmless radioactive labels. This blood is injected back into the body. Special detectors can then monitor where these tagged WBCs go during an inflammation.
Endoscopic ultrasound
Endoscopic ultrasound (EUS) is another imaging study that can be used. In this an ultrasound probe is attached to an endoscope that helps to look under the lining of the intestines as well as the intestinal walls. These can help detect fistulas and the extent of spread of ulcers in the inflammatory bowel diseases.
Further Reading
Genetic variant identified as potential predictor for severe ulcerative colitis