How much blood is needed for occult in stool to be positive?

Occult blood in the stool refers to the presence of blood that cannot be seen with the naked eye. It is detected through chemical testing of a stool sample. The amount of blood needed for a positive occult blood test can vary depending on the sensitivity of the test used. In general, most occult blood tests can detect blood when present in concentrations as low as 2 milliliters (mL) of blood per liter (L) of stool. However, some highly sensitive tests can detect even smaller amounts of blood, down to 0.5 mL of blood per L of stool.

It's important to note that a positive occult blood test does not necessarily indicate a serious underlying condition. It may require further investigation, such as colonoscopy or other diagnostic tests, to determine the source of the bleeding and rule out any potential health issues.