Occult Blood in Stool Test: What's a Positive Result?

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.