Hemocue America Hemocue Gastroccult Test. The only rapid test designed specifically for detecting gastric occult blood and determining gastric pH in one device. This CLIA Waived test gives results in 30 seconds for pH, and 60 seconds for occult blood, and includes a convenient pH comparison chart for the clinically relevant range. With an on-slide Performance Monitor, it can detect low levels of blood in samples containing bile, eliminating subjective visual judgments.