For stool specimen collection, which instruction is important to give?

• A. Avoid caffeine
• B. Avoid red meat
• C. Increase fluid intake
• D. Remain NPO after midnight

Answer: (B)

The important idea here is that what you eat can affect the accuracy of stool-based tests, especially those used to detect hidden blood (occult blood). Red meat contains heme that can trigger reactions in some occult blood tests and mimic a positive result, leading to a false indication of GI bleeding. To prevent this interference, patients are instructed to avoid red meat for several days before collecting a stool sample.

Caffeine and increasing fluids do not impact the test results in the same way, and remaining NPO after midnight isn’t needed for stool collection. So avoiding red meat is the best instruction to ensure an accurate stool specimen test.