Abstract: A tubular test device for testing occult blood in fecal matter using hydrogen peroxide in an ampoule and 3,3',5,5'-tetramethylbenzidine as the chromogen dissolved in chloroform to impregnate a cellulosic pledget which, when dried, is substantially colorless and is introduced adjacent a sampling swab into the device to lie adjacent the ampoule containing dilute hydrogen peroxide and a wetting agent. A special conditioning pre-coating for the pledget before impregnation with liquid chromogen in chloroform is provided consisting of hydroxyethylcellulose dissolved in an aqueous non-volatile acid buffer such as citric acid and sodium citrate to maintain a pH of 5-7, and then dried. The swab takes a sample of fecal matter. A cap is placed over the swab. The ampoule is broken.