A red line on fecal occult blood test paper suggests that this result is valid and negative for fecal occult blood and no bleeding in the digestive tract. Fecal occult blood test paper can be used to initially determine whether there is bleeding in the feces, especially the appearance of the feces without abnormal changes, if a red line is the quality control line, suggesting that this result is valid, and the result is negative, there is no occult blood phenomenon. If there are two red lines on the fecal occult blood test paper, it suggests that the result is positive, and there may be bleeding in the digestive tract, such as ulcerative colitis, hemorrhoidal bleeding, and also be alert to bleeding caused by infiltration and invasion of gastrointestinal tumors. If there is no red line on the fecal occult blood test paper, the result is invalid and another test is needed. When the fecal occult blood test paper results are abnormal, the cause should be carried out under the guidance of a doctor in order to actively treat.