1, iron-rich food: the examination of occult blood test can check whether there are red blood cells in stool and urine, and whether the patient has bleeding. Patients should avoid eating iron-rich foods such as duck blood, pig blood and chicken blood for three days, because the intake of these foods usually increases the number of red blood cells, leading to false positive results in occult blood test;

2. Foods rich in vitamin C: Foods rich in vitamin C, such as spinach, vegetables and leeks, should also be avoided in the diet. Because these foods contain a lot of vitamin C, nitrite will be reduced to negative if urine contains Escherichia coli. May not be detected;

3. Iron supplements: It is recommended not to take iron supplements, such as compound ferrous sulfate granules and ferrous sulfate tablets. It may lead to false positive of occult blood test and affect the doctor's judgment of physical condition.