Blood that has been digested by stomach acids can manifest as:

When blood that has been digested by stomach acids is expelled from the body, it typically appears as coffee grounds emesis. This coloration results from the interaction of the blood with gastric acids; the acid breaks down the hemoglobin in the red blood cells, leading to the dark, granular appearance that resembles coffee grounds.

This phenomenon often indicates an upper gastrointestinal bleed, such as from ulcers or esophageal varices, where the blood has had time to react with the stomach's digestive enzymes and acids. The significance of this presentation is crucial in determining the source and severity of the bleeding, guiding further medical evaluation and management.

In contrast, hematochezia refers to the passage of fresh red blood from the rectum, usually indicating a lower gastrointestinal bleed. Bright red vomitus would indicate fresh blood from the upper GI tract, while gray-colored stool suggests a lack of bile or a significant obstruction, not digested blood. Thus, the other options pertain to different types of bleeding or blood appearance that do not match the description of digested blood.