Cologuard offers a non-invasive option for colorectal cancer screening, which can be appealing for many individuals. However, receiving a positive Cologuard result can cause concern, especially when other conditions like hemorrhoids are present. Understanding how this test works and the potential impact of common conditions can help clarify such results.
How Cologuard Works
Cologuard is a stool-based test designed to screen for colorectal cancer and precancerous polyps. It uses a multi-target approach, analyzing stool samples for specific markers associated with these conditions. The test primarily looks for two types of indicators: altered DNA and hidden blood (hemoglobin).
Cells from the lining of the colon are continuously shed into the stool. Cologuard detects DNA changes in these shed cells that are linked to colorectal cancer or advanced adenomas. In addition to DNA markers, the test also identifies the presence of human hemoglobin, which can indicate bleeding in the gastrointestinal tract. A positive result is determined by combining the findings from both the DNA and hemoglobin analyses.
Understanding Hemorrhoids and Bleeding
Hemorrhoids are swollen veins located in the lower rectum or around the anus. They are a common condition, often described as similar to varicose veins. Hemorrhoids can be internal, forming inside the rectum, or external, developing under the skin around the anus. While internal hemorrhoids are usually painless, they frequently cause bleeding, which may appear as bright red blood on toilet tissue or in the toilet bowl after a bowel movement. External hemorrhoids can also bleed, but they are often associated with itching, pain, and swelling.
Straining during bowel movements, chronic constipation, or prolonged sitting can increase pressure in the anal veins, leading to hemorrhoid formation and bleeding.
Connecting Hemorrhoids to Cologuard Results
Hemorrhoids can indeed contribute to a positive Cologuard test result. Cologuard is designed to detect the presence of occult (hidden) blood in the stool, regardless of its source. Therefore, bleeding from hemorrhoids, even if minor, can trigger the hemoglobin detection component of the Cologuard test.
It is important to recognize that Cologuard cannot distinguish between blood from hemorrhoids and blood from polyps or cancerous growths. The test identifies the presence of blood, which then contributes to the overall positive finding. While Cologuard also analyzes specific DNA markers associated with cancer, the presence of blood from any source can lead to a positive result. A positive test due to hemorrhoids does not mean the test is “wrong,” but rather that it has detected a marker that warrants further investigation, as a positive Cologuard test has a false-positive rate of approximately 13%.
Next Steps After a Positive Test
Receiving a positive Cologuard result requires a follow-up with a healthcare provider for further evaluation. A positive result indicates that the test detected altered DNA and/or blood in the stool that could be caused by a precancerous polyp or colon cancer. It does not, however, equate to a cancer diagnosis.
The standard next step after a positive Cologuard test is a diagnostic colonoscopy. A colonoscopy allows for a direct visual examination of the colon and rectum, enabling a healthcare provider to identify the source of any bleeding or abnormal growths. During this procedure, any suspicious areas or polyps can be biopsied or removed. Self-diagnosis based on the presence of hemorrhoids is not recommended, as it could delay the detection of more serious conditions. As of 2023, Medicare, ACA, and commercial plans generally cover a follow-up colonoscopy after a positive non-invasive stool-based test.