Immunochemical testing for faecal occult blood in patients with colorectal cancer.

Eighty-six stool specimens collected from 36 patients with colorectal cancer were tested for occult blood by chemical and immunochemical methods. There was no dietary restriction. Positive results were obtained in 94% of patients by the immunochemical method when the presence of any positive immunochemical test was taken as a positive result. If greater than 1 mg of haemoglobin per gram of faeces was regarded as positive result, then 75% of patients would have been diagnosed as having occult blood in the stool by means of the immunochemical method. Positivity rates for Hemoccult II and rehydrated Hemoccult II were 53% and 81%, respectively.