A screening test for disorders of the gastrointestinal tract, including anemias that may be caused by gastrointestinal blood loss, e.g., cancer of the colon. Traditionally, a small amount of feces is collected on cards accompanying several consecutive bowel movements. These cards are submitted to a lab for analysis. Alternately, a flushable pad is dropped into the toilet bowl after a bowel movement. A change in color (to blue or green) in the pad reveals occult blood if present.

PATIENT CARE
Patients should be taught how to collect and protect card specimens submitted to the laboratory. They should avoid taking NSAIDs such as ibuprofen or aspirin and should not take more than one adult aspirin (325 mg) per day for several days prior to and during specimen collection. They should also avoid red meats (including cold cuts) for 3 days before and during the testing period, and limit vitamin C intake to less than 250 mg/day. The patient should avoid contaminating the stool sample by not allowing it to touch the toilet or the water. The bowel movement should be made into a clean, dry container or onto the flushable collection tissue supplied with the kit. A wooden stick or swab transfers a small quantity of the specimen to the collection card. Specimens should be protected from heat, light, and chemicals. When developing the test, the health care professional makes sure the developer to be used is compatible with the sampling kit. Gloves should be worn and standard precautions followed. If the specimen is fresh, 3 to 5 min should elapse before adding developer to make sure the stool has penetrated the paper. The manufacturer’s instructions should be followed precisely. For all guaiac tests, a blue color indicates the presence of blood. Blue-green also may indicate blood, while green alone is considered negative. After reading the results, the positive and negative controls should be tested to verify test accuracy. The results are then documented. Care should be taken to be sure that a test kit is not used after its expiration date. Specimens should not be collected or the test run if blood can be seen in the stool or urine, if the patient is menstruating, or if a urinary tract infection is present.

The developer bottle should be stored in a lab area rather than left in a patient area, as it could be mistaken for a liquid medication or a toy.