Anti Saccharomyces Cerevisiae (ASCA), IgA Test

Inflammatory bowel disease (IBD) is primarily of two types - Crohns disease (CD) and ulcerative colitis (UC). IBD is inflammation of the small/large intestine. A case of IBD is detected by conducting a barium X-ray, colonoscopy or mucosal biopsy histology of the intestine. A person with IBD will complain of rectal bleeding, abdominal pain and discomfort, diarrhea, fatigue, fever and other organ related problems. Saccharomyces Cerevisiae is yeast commonly used in food industry. Patients with IBD have Anti Saccharomyces Cerevisiae Antibodies or ASCA. The test for Anti Saccharomyces Cerevisiae Antibodies (ASCA) helps to distinguish between Crohns disease and ulcerative colitis. Persons with IBD often have ASCA or immune proteins in their blood. Two different classes of ASCA in the blood – IgA and IgG are tested. ASCA IgA test is performed on a sample of blood.

Prior to ASCA IgA blood test, no special preparation is required. You need to visit your doctor at the onset of any symptoms similar to having an IBD. Discuss your medical history, lifestyle, any allergies, health condition and on-going medication if any. You will receive specific instructions from the doctor which is to be followed. The doctor may advise you to discontinue any current medication. Like other blood tests, it’s recommended to wear sleeveless or short sleeve dress to allow hassle free blood sample collection.

Antibodies to Saccharomyces Cerevisiae are usually found in approximately 75% of patients with Crohns disease, 15% of patients with ulcerative colitis, and 5% of the healthy population. A positive ASCA confirms Crohns disease and a negative ASCA confirms ulcerative colitis. A normal ASCA IgA result indicates no IgA antibody. A positive ASCA IgA result indicates Crohns disease. As the inflammation in Crohns disease is focused at the gut mucosa, IgA antibodies to Saccharomyces cerevisiae in most patients are found.

A minimum of 5 ml blood is drawn in adults as sample using venipuncture. In case of a paediatric, 2 ml blood is drawn as sample. Upon ordering ASCA IgA test, first, the phlebotomist ties a tourniquet to your upper arm to locate the vein. An alcohol based antiseptic is applied to the needle site. A disposable needle is then pushed gently into the vein and the tourniquet is released. The blood sample is collected in a labelled red top tube without any anticoagulants or other additives. Laboratory testing using Enzyme Linked Immunosorbent Assay (ELISA) method is done.