What are some factors which can affect the results of fecalysis?
1) Medications that irritate the gastric mucosa such as non-steroidal anti-inflammatory medicines (NSAIDs), anticoagulants, colchicine, corticosteroids, phenylbutazone, and iron preparations can cause positive results for occult blood
2) High doses of vitamin C (more than 250 mg per day) can cause false negative occult blood
3) Dietary intake of high in red meat, certain vegetables (radish, turnips, cauliflower, broccoli), and fruits (bananas, apples, cantaloupe) can cause false-positive results for occult blood
4) Constipated stools may not show any trypsin activity due to prolonged exposure to intestinal bacteria
5) Bismuth found in toilet tissue interferes with the results.
6) Wrong collection and storage of stool samples.
8) Lifestyle, personal habbits, environments may influence the results.