Differentiating Upper from Low GI Bleeding 1g Hematochezia usually represents a lower GI source bleeding pper gi lesion may bleed so briskly that blood doesn t remain in bowl long enough to become melena Bleeding lesion distal to T Lig. may be either m. or hematochezia, but never manifests hematemesisDifferentiating Upper from Low GI Bleeding Hematochezia usually represents a lower GI source bleeding Upper GI lesion may bleed so briskly that blood doesn`t remain in bowl long enough to become melena Bleeding lesion distal to T Lig.may be either M.or hematochezia, but never manifests hematemesis