A nurse is caring for a client who will perform fecal occult blood testing at home. Which of following information should nurse include when explaining procedure to client?

Correct Answer: D. The specimen cannot be contaminated with urine.

For fecal occult blood testing at home, the stool specimens cannot be contaminated with water or urine. The fecal occult blood test (FOBT) is a diagnostic test to assess for occult blood in the stool. This test has commonly been used for colorectal cancer screening, especially in developed nations. When used correctly for screening, this testing modality has established associations with decreased morbidity and mortality. When performing at home, the stool should be collected in a dry, clean container.

• Option A: Some proteins such as red meat, fish, and poultry can alter the test results. Three days prior to fecal occult blood testing, avoidance of certain foods should be to help prevent false test results. False-positive results have been associated with red or rare meat as well as raw fruits and vegetables, including but not limited to horseradish, raw turnips, cantaloupe, broccoli, cauliflower, parsnips, and red radishes. False-negative results are also known to occur in patients taking ascorbic acid (vitamin C) in excess of 250mg/day.
• Option B: Three specimens from three different bowel movements are required. One problem with FOBT is the need for medication and dietary restrictions before testing. These restrictions are in order to decrease the risk of false negative and false-positive results. Many studies assessing the risk of these false results exist. One particular retrospective study evaluated the medications that could create false-positive results and encouraged patients to avoid these medications, if possible, for seven days before testing. The listed medications include acetylsalicylic acid, unfractionated or low-molecular-weight heparin, warfarin, clopidogrel, nonsteroidal anti-inflammatory drugs, and selective serotonin reuptake inhibitors.
• Option C: A blue color indicates blood in the stool. If the patient’s fecal occult blood test does not turn blue, it is negative. If the card turns blue, this is positive and requires further gastroenterological workup.