Cologuard is a non-invasive, stool-based DNA test designed to screen for colorectal cancer and precancer in average-risk individuals. Unlike traditional methods, this at-home test requires no special dietary restrictions or bowel preparation, making it a convenient option for many people. The process involves several distinct steps, from sample collection to receiving the final result.
The Cologuard Sample Collection and Shipping Process
The process begins after a healthcare provider orders the test, and the collection kit is mailed directly to the patient’s home. The kit contains all the necessary components for sample collection, including a container and a preservative liquid, along with detailed instructions. Patients complete the collection in the privacy of their home, ensuring the stool sample is properly secured in the container and the preservative is added to stabilize the genetic material.
Patients are instructed to ship the kit back to the Exact Sciences laboratory using the provided prepaid UPS label on the same day as collection, or the following day at the latest. The goal is for the sample to reach the lab within 72 hours of collection to ensure the DNA remains viable for analysis. It is generally recommended to avoid collecting the sample immediately before weekends or holidays to prevent shipping delays.
Typical Laboratory Processing Timeline
Once the collected sample arrives at the laboratory, it is immediately logged, assigned a unique identification number, and prepared for processing. The time it takes from the lab receiving the sample to the final result being sent to the ordering physician is typically between 8 and 10 days. However, some sources may quote a slightly longer turnaround time of up to two weeks from the lab’s receipt.
Several factors can influence this processing timeline, including the current volume of tests the lab is handling, which can be affected by seasonal screening trends. If the sample quality is compromised—for instance, if the collection was incomplete or the sample was not shipped back promptly—the lab may be unable to complete the analysis. In these cases, the patient may be contacted and a new collection kit may need to be sent out. The final result is delivered directly to the healthcare provider who ordered the test, who is then responsible for communicating it to the patient.
Interpreting Cologuard Results: Positive vs. Negative
Cologuard is a multi-targeted stool DNA test that works by analyzing the sample for two main types of biological markers associated with colorectal neoplasia. The test looks for specific DNA alterations shed by abnormal cells, such as those found in cancerous tumors or precancerous polyps. Concurrently, the test also checks for the presence of occult, or hidden, blood in the stool by measuring a protein called hemoglobin.
A “Negative” Cologuard result indicates that the test did not detect the targeted abnormal DNA markers or occult blood, suggesting a lower-than-average probability of having colorectal cancer or an advanced precancerous lesion. Conversely, a “Positive” result means the test has detected the presence of these specific DNA changes and/or blood biomarkers. A positive result is not a cancer diagnosis; it simply signifies an elevated risk that warrants further investigation. This screening tool has a known false positive rate, meaning some individuals with a positive result will not have cancer or advanced polyps upon follow-up.
Required Follow-Up After a Positive Cologuard
A positive Cologuard result requires a prompt, diagnostic follow-up procedure to determine the cause of the detected biomarkers. The only appropriate next step following any positive stool-based screening test is a diagnostic colonoscopy. This procedure is necessary because Cologuard is a screening tool, not a diagnostic one, and only the colonoscopy allows for visual confirmation and tissue analysis.
During the colonoscopy, a gastroenterologist can visually inspect the entire colon for the presence of polyps or cancerous growths. If any suspicious tissue is found, it can be removed immediately and sent for a biopsy to establish a definitive diagnosis. This follow-up colonoscopy should be scheduled as soon as possible, ideally within three months of the positive result. Recent changes in coverage mean that the follow-up colonoscopy after a positive non-invasive test is often covered as part of the screening process, minimizing out-of-pocket costs for many patients.