What Is the Poppy Seed Test?

In medicine, doctors typically administer the poppy seed test to pre-surgical patients suspected of having colovesical fistula, which is an abnormal pathway between the bladder and the colon. After consuming poppy seeds, patients with this condition will not digest them, which will cause the seeds to appear in the urine. Although the test is not standard procedure in many countries, it can provide physicians with an accurate assessment and allow urologists the ability to judge whether a patient requires surgery.

The poppy seed test was discovered by a group of German urologists in 1994, and was described in the Journal of Urology in 2001. From 1994 to 1999, German urologists administered 8.8 ounces (250 g) of poppy seeds to 17 patients. After monitoring each patient's urine for two days, the urologists discovered that the 11 patients found to have colovesical fistula passed the seeds in their urine. The six patients who did not have colovesical fistula did not pass them in this way.

Normally, the urinary system is not connected to a patient's alimentary canal, however, some conditions — such as diverticulitis, colorectal cancer (CRC), appendicitis, and Crohn's disease — might cause colovesical fistula to develop. Patients who pass urine rectally, have reoccurring urinary tract infections, or have been diagnosed with pneumaturia or faecaluria, generally have colovesical fistula. In these cases, doctors usually administer the poppy seed test and, if the test reveals a positive result, perform surgery to remove the fistula.

Doctors generally use several diagnostic methods to determine whether a patient has a colovesical fistula, such as a fluoroscopy, computerized tomography (CT) scan, or an endoscopy. Although alternative diagnostic methods generally diagnose the disease, the results are only 70% to 80% accurate. While studying the poppy seed test, doctors have discovered that the test provides 100% accuracy in diagnosing patients, making it the most accurate test available.

In addition to the accuracy of the poppy seed test, doctors have also discovered that the procedure is significantly less costly to conduct. In a study performed between 2000 and 2006, doctors used three methods to diagnose 20 patients with confirmed cases of colovesical fistula — a radio-labeled chromium test, a CT scan, and the poppy seed test. The cost to administer the poppy seed method is approximately $5 US Dollars (USD), however, the cost to administer a radio-labeled chromium test or a CT scan can exceed $500 USD.