There are several at-home tests that screen for colon cancer, but experts say there is nothing like a colonoscopy to get precision results. In 2014, the Food and Drug Administration approved Cologuard, a non-invasive colorectal screening test that looks for blood and DNA mutations in stool. Other stool tests include the fecal immunochemical test, or FIT, and the fecal occult blood test, or FOBT, according to Michigan Medicine, a division of the University of Michigan.

According to Fort HealthCare of Fort Memorial Hospital in Wisconsin, these are potentially valuable screening tools for those who are adamant about not having a colonoscopy or those who simply cannot have one for medical reasons. However, stool tests can lead to a number of false positive results, which can be worrisome for the patient and lead to a colonoscopy anyway.

Here are four reasons why a colonoscopy is still the gold standard of screening for colorectal cancer:

• A colonoscopy checks your entire colon for cancer and polyps which could become cancerous. The procedure is thorough and only has to be performed every 10 years in most circumstances. Stool tests need to be repeated every 3 years or less and do not examine the whole colon.
• Colonoscopies not only detect cancer but prevent it. During the procedure if the doctor finds a polyp, he or she can remove it before it becomes cancerous. This isn’t possible with stool tests.
• False positive results are common in stool screening tests because other common conditions, such as hemorrhoids, can cause blood in the stool. According to Michigan Medicine, other ailments that produce blood are anal fissures, peptic ulcers, ulcerative colitis, and gastroesophageal reflux disease, or GERD.
• You may still need a colonoscopy if you get a positive result from your Cologuard test or other screening test to rule out cancer and find out the cause of bleeding.

According to Michigan Medicine, it is important to discuss your health risks and preferences with your doctor before scheduling any screening procedure for colorectal cancer.