What Happens After a Positive At-Home Stool Test?

A positive at-home stool test means you need a colonoscopy. That holds whether it was a FIT or a stool DNA test such as Cologuard.

Not a repeat stool test. Not a wait-and-see. Not a blood test instead. The American Cancer Society states it directly: any abnormal result on a screening test other than colonoscopy should be followed up with a timely colonoscopy.

Everything else on this page is context for that one instruction.

This is the most common wrong turn, and it usually comes from a reasonable place. The test was done at home. It feels imprecise. Rechecking seems sensible.

But a second stool test cannot undo the first. USPSTF reports that FIT detects colorectal cancer with pooled sensitivity of 0.74. For stool DNA (sDNA-FIT) it is 0.93. So a negative repeat fits with a cancer being present. Treating it as reassurance just turns a positive screen into a delay.

Stool tests sort people into two groups. One group can wait for the next round. The other needs the colon looked at directly. Once you are in the second group, another stool test has no role.

How quickly the colonoscopy happens matters. This was measured in a large cohort study of 70,124 people with positive FIT results (Kaiser Permanente, JAMA 2017). Compared with colonoscopy performed within 8 to 30 days:

• At 10 to 12 months, the odds of finding any colorectal cancer were 48 percent higher, and the odds of advanced-stage disease were 97 percent higher.
• Beyond 12 months, the odds of any colorectal cancer were more than double, and the odds of advanced-stage disease roughly triple.

In that study, waits of up to 9 months showed no significant difference. The higher risk showed up at 10 months and beyond. The study shows a link. It could not prove that the delay caused the difference. Do not use it as permission to wait. Ask for the soonest appointment.

And not going at all is worse than any delay. NCI reports on a study in Italy. People who did not have a follow-up colonoscopy were about twice as likely to die of colorectal cancer over ten years as those who did. NCI says the likely reason is that their cancers were found only after symptoms appeared, when the cancer was more advanced.

This is worth holding onto during the wait.

In the Kaiser Permanente study, 2,191 of the 70,124 people with a positive FIT who had a colonoscopy were found to have colorectal cancer. USPSTF reports pooled specificity of 0.94 for FIT and 0.84 for stool DNA. So some positive results occur in people who do not have cancer.

MedlinePlus lists hemorrhoids and anal fissures among non-serious causes of bleeding from the digestive tract. It also lists cancer and polyps. Only the colonoscopy can tell which it is.

Finding a polyp is a chance to prevent cancer. NCI says doctors can remove polyps during a colonoscopy, which reduces the risk of future cancers.

The weak point in this process is not the test and not the colonoscopy. It is the scheduling in between.

In health systems in a CDC screening program, follow-up colonoscopy completion after an abnormal stool test averaged 47.9 percent. It ranged from 24.2 to 75.5 percent. NCI reports that some programs have follow-up rates as low as 50 percent. A program in Italy reached 80 percent at 3 months. The gap is logistics. Referrals that never get placed. Preparation instructions that go unread. Transportation and time off work. And the quiet hope that a good feeling means it can wait.

Some practical steps help. Before you leave the appointment or hang up the phone, get the name and number of whoever books the procedure. Ask for the soonest appointment rather than the most convenient one. Arrange your ride in advance, since sedation means you cannot drive yourself. Read the bowel preparation instructions the day you get them, not the day before.

Federal rules require most private health plans to cover a colonoscopy after a positive stool-based screening test, without cost sharing, for plan years beginning on or after May 31, 2022 (U.S. Department of Labor). Medicare Part B covers a follow-up colonoscopy after a positive stool test as a screening test. If your provider accepts assignment, you pay nothing. If the provider finds and removes a polyp, you pay 15% of the Medicare-approved amount for the provider's services. A hospital outpatient setting or surgery center may also charge a 15% facility coinsurance.

Billing codes can still vary in practice. So call your plan and ask specifically about a follow-up colonoscopy after a positive stool-based screening test. Confirm how the order will be coded.

If nothing is found, you generally return to routine screening on the interval your care team sets. If polyps are removed, the pathology results help decide when your next colonoscopy is due. If cancer is found, it was found by a screening process working as designed. NCI says that for some cancers, the chance of recovery is better if the disease is found and treated at an early stage.

The positive result was not the bad news. Not acting on it would be.

Waiting for a colonoscopy date is not a reason to wait out a new symptom.

• Call 911 or go to an emergency department if bleeding from your back passage will not stop, or there is a lot of blood, such as the toilet water turning red or large clots coming away. Do the same if bleeding comes with feeling faint, cold, or clammy, lightheaded, or breathless, or with chest pain (MedlinePlus). Do not drive yourself.
• Call 911 or go to an emergency department if your stool turns black and tarry, or belly pain becomes severe along with bleeding (MedlinePlus). Do not drive yourself.
• Call 911 or go to an emergency department if you vomit blood, or vomit material that looks like coffee grounds (MedlinePlus). Do not drive yourself.
• Call your care team right away if you see any blood in your stool or its color changes (MedlinePlus).
• Call your care team right away if belly pain becomes severe without bleeding. Go to an emergency department if the pain is sudden, or comes with vomiting or a hard, tender belly (MedlinePlus).
• Call your care team within a day or two if your usual bowel pattern changes and stays changed, or you feel drained.

The bleeding guidance above follows MedlinePlus on gastrointestinal bleeding, bloody or tarry stools and abdominal pain.

• American Cancer Society colorectal cancer screening recommendations
• USPSTF: Colorectal cancer screening recommendation
• NCI: Colorectal Cancer Screening (PDQ) - Patient Version
• NCI: Colonoscopy after Positive FIT Test Cuts Risk of Colorectal Cancer Death
• Corley et al., JAMA 2017: Time to colonoscopy after a positive fecal test and risk of colorectal cancer and stage at diagnosis (PubMed abstract)
• FAQs About Affordable Care Act Implementation Part 51 (colonoscopy after a positive stool-based test, no cost sharing)
• Medicare.gov: Colonoscopies (screening)
• Follow-up colonoscopy completion in CDC's Colorectal Cancer Control Program
• MedlinePlus: Gastrointestinal bleeding