OC-Light S FIT (Fecal Immunochemical Test, also known as iFOBT, immunochemical fecal occult blood test) is an immunochemical test intended for the detection of fecal occult blood (FOB) by professional laboratories and physician office laboratories. The measurement of FOB is useful as an aid to detect blood in stools when gastrointestinal (GI) bleeding may be suspected. OC-Light S FIT is recommended for use in routine physical examinations, monitoring and screening for GI bleeding in patients.