The clinical trial entitled "Detection of upper gastrointestinal (GI) bleeding with a novel bleeding sensor capsule - a pilot study" was carried out in a monocentric clinical trial with 30 patients as part of the final development phase of the HemoPill acute, a bleeding sensor capsule. The swallowable capsule operates with the combination of an optical sensor for blood detection positioned within a recess in the capsule surface and a radio interface for wireless transmission of sensor data to an external receiver device. The HemoPill acute capsule is used for diagnosis of patients with suspected acute upper gastrointestinal bleeding.