A positive erythrocyte test often means that red blood cells are found in the specimen tested, indicating that the presence of red blood cells in the specimen obtained is often evidence of bleeding in an organ. The presence of red blood cells in urine indicates that there may be bleeding in the genitourinary system. There are many common diseases, including inflammation, neoplastic diseases, stones, tuberculosis, etc. For example, patients with bladder cancer can have painless hematuria, which is characterized by strong positive red blood cells in the urine. If the stool test is positive for red blood cells, it often indicates the presence of bleeding in the digestive tract, which can be caused by ulcers, bleeding, tumors, inflammation, etc. For example, patients with gastric cancer can have a positive stool test for red blood cells. Therefore, positive red blood cells often indicate localized bleeding.