A colonoscopy is a medical procedure used to visually examine the colon and rectum using a flexible tube with a camera attached. During this examination, the physician may remove a small piece of tissue for laboratory analysis, which is known as a biopsy. Taking a tissue sample is a routine part of the procedure and should not be a cause for immediate alarm. This step provides a definitive, microscopic understanding of the tissue’s nature that visual inspection alone cannot.
Why Taking a Sample is Standard Practice
The most frequent reason for removing tissue is the discovery of polyps, which are growths on the inner lining of the colon. Even if a polyp appears visually harmless, a biopsy is necessary to determine its exact cellular type. Removing and analyzing these polyps is a preventative measure against future colorectal cancer development.
Polyps are classified as either non-neoplastic (benign) or neoplastic (precancerous or cancerous). Hyperplastic polyps are typically non-neoplastic and do not pose a cancer risk. In contrast, adenomatous polyps are considered precancerous because they have the potential to develop into cancer if they are not removed. The removal of these growths during the colonoscopy is called a polypectomy and is a fundamental part of cancer screening.
Specific Conditions That Require Biopsy
Beyond polyps, a biopsy is often taken to investigate changes in the mucosal lining. The physician may sample areas that exhibit redness, swelling, irritation, or ulcerations. This is done to diagnose conditions characterized by inflammation or abnormal cell growth that are not necessarily polyps.
A biopsy is particularly important for diagnosing Inflammatory Bowel Disease (IBD), which includes Crohn’s disease and Ulcerative Colitis. These conditions show chronic inflammation in the colon lining, and the tissue sample helps differentiate between the two and assess the disease’s activity. In some cases, the colon lining may appear normal during the visual exam, but a biopsy is still required to diagnose microscopic colitis. Microscopic colitis involves inflammation that is only visible when the tissue is examined under a powerful microscope.
What Happens to the Tissue Sample
Once the tissue sample is removed using tiny forceps passed through the colonoscope, it is immediately placed into a container. This container holds a chemical substance, which acts as a fixative. The fixative stops the cells from degrading and preserves their structure for later examination.
The sample is carefully labeled with the patient’s information and the precise location within the colon where it was taken. It is then transported to a specialized pathology laboratory where a pathologist, a doctor trained in diagnosing disease by examining tissues, takes over. The pathologist processes the sample by embedding it in wax, slicing it into thin sections, and staining it with special dyes. These steps allow the cellular architecture to become visible under the microscope.
The pathologist analyzes the cells to determine if they are normal or if they show signs of disease, such as inflammation or abnormal growth. The complete process, from collection to analysis and report generation, typically takes several days to a week. The final report is then sent to the physician who performed the colonoscopy.
Understanding What the Results Mean
The pathology report uses specific terminology to describe the findings. A benign result means the tissue is non-cancerous, such as a hyperplastic polyp or normal inflammation. These findings generally suggest a routine screening schedule for the next colonoscopy, often in ten years.
If the report mentions an adenoma or sessile serrated lesion, the finding is precancerous, meaning the cells show abnormal growth called dysplasia. Dysplasia is a change in the tissue that is not cancer but has the potential to become cancer over time. This is categorized as low-grade dysplasia, which suggests slow-growing changes, or high-grade dysplasia, which indicates more advanced cellular abnormality.
The presence of precancerous lesions determines the patient’s surveillance schedule, which is often shortened to three or five years to ensure new growths are detected early. If the report uses the term carcinoma or invasive adenocarcinoma, it signifies that cancerous cells were found. This finding prompts immediate discussion with the physician about further tests and treatment options, which may include surgery.