Urinalysis and Body Fluids 6th Edition by Majorie DiLorenzo, Susan Strasinger

Exercise 7

A physician’s office laboratory is experiencing inconsistencies in the results of patient-collected specimens for FOBT. Patients are instructed to submit samples from two areas of three different stools. Positive and negative controls are producing satisfactory results. Patient #1 is a 30- year-old woman taking over-the-counter medications for gastric reflux who has reported passing frequent, black stools. The results of all three specimens are negative for occult blood. Patient #2 is a 70-year-old woman suffering from arthritis. She is taking the test as part of a routine physical. The results of all three specimens are positive for occult blood. Patient #3 is a 50-year-old man advised by the doctor to lose 30 lb. He has been doing well on a high-protein, low-carbohydrate diet. Two of his three specimens are positive for occult blood.

a. What is the possible nonpathologic cause of the unexpected results for Patient #1? Patient #2? Patient #3?

b. How could the physician’s office staff avoid these discrepancies?

c. What testing methodology could be used for Patients #2 and #3?

Step 1 of 3

a.

The following are the possible non pathological causes for the unexpected results in patient #1, patient #2, and patient #3

• Patient #1 had taken medicines for gastric reflux. The medicine contains bismuth, which can cause black color stool

• Patient #2 had taken the medicines aspirin and NSAID (Nonsteroidal anti-inflammatory drug) that caused gastric bleeding

• The patient #3 didn’t avoided red meat in her diet 3 days prior to the collection of sample