Hemoccult screening in selected patients.

One hundred patients, asymptomatic relative to gastrointestinal disease, who applied for elective hernia repair were tested as outpatients for occult blood in the stool. Twenty-six had one or more positive specimens. Among this group colonic disease was found in seven, including adenocarcinoma (Dukes' stage A) in one, adenomatous polyps in three, and colonic diverticula in the remainder. The unexpectedly high false-positive rate (33%) was reduced markedly by giving a meat-free diet before stool collection. Patient compliance was excellent and the cost-benefit ratio appeared to be acceptable.