Doctors may take biopsies during a colonoscopy because some colorectal conditions cause cellular changes that cannot be seen with the camera. A tissue sample allows a pathologist to examine the colon lining under a microscope and identify inflammation, abnormal cells, or other evidence that may explain a patient’s symptoms.
At the Center for Colorectal Disease of Arizona, we may recommend biopsies based on a patient’s symptoms, medical history, and the reason for the procedure, even when the colon appears normal during the examination.
What Can a Doctor See During a Colonoscopy?
A colonoscopy uses a thin, flexible tube with a camera to examine the inner lining of the colon and rectum. It allows a colon rectal doctor to identify visible abnormalities such as:
- Polyps
- Inflamed or ulcerated tissue
- Areas of bleeding
- Narrowed sections of the colon
- Diverticula
- Masses or other unusual growths
The procedure can be used for colorectal cancer screening, evaluating symptoms, monitoring an existing condition, or following up on previous findings. During our colonoscopy services , tissue samples or polyps may be collected when medically appropriate.
For adults at average risk, the American Cancer Society recommends beginning colorectal cancer screening at age 45, with a colonoscopy every 10 years as one screening option. The interval may be shorter for patients with symptoms, previous polyps, inflammatory bowel disease, a family history of colorectal cancer, or other risk factors.
Why Can Normal-Looking Tissue Still Require Testing?
A colonoscopy provides a detailed view of the colon’s surface, but the camera cannot show individual cells. Tissue may appear smooth and healthy while changes are occurring at the microscopic level.
A biopsy gives the physician information that visual inspection alone cannot provide. The pathologist processes the sample, examines its cellular structure, and reports whether there are signs of inflammation, infection, precancerous changes, or another abnormality.
Taking a biopsy does not necessarily mean the colorectal surgeon suspects cancer. It is a diagnostic step used to gather more complete information and avoid relying only on what is visible during the procedure.
Which Conditions May Be Found Through a Biopsy?
One important example is microscopic colitis. This condition can cause persistent watery diarrhea even though the colon lining often looks normal during a colonoscopy. Its two primary forms, collagenous colitis and lymphocytic colitis, are diagnosed by examining tissue samples under a microscope.
Biopsies may also help evaluate:
- Ulcerative colitis or Crohn’s disease
- Inflammation that is mild or not visually obvious
- Changes associated with certain infections
- Abnormal cellular development
- The type of tissue within a polyp or lesion
- Treatment response in a previously diagnosed condition
The locations and number of samples depend on the clinical question. A colon specialist may collect tissue from several parts of the colon because some microscopic conditions are not distributed evenly.
Does Every Colonoscopy Include a Biopsy?
No. Whether a biopsy is needed depends on why the colonoscopy is being performed and what the physician observes.
A routine screening examination may not require random tissue samples if the colon appears healthy and the patient has no symptoms suggesting a microscopic disorder. However, a biopsy may be appropriate if the procedure is being performed to investigate chronic diarrhea, rectal bleeding, unexplained bowel changes, inflammation, or an abnormal imaging or laboratory result.
If a polyp is found, it may be removed and sent for analysis. Removing an entire polyp is technically different from collecting a small biopsy, although both involve laboratory examination of tissue.
What Happens When a Biopsy Is Collected?
Small instruments are passed through the colonoscope to collect tiny pieces of tissue. Patients are typically sedated for the procedure and generally do not feel the tissue collection itself.
The sample is preserved and sent to a pathology laboratory. A pathologist then evaluates the tissue and provides a report to the physician. Results are not usually available immediately after the colonoscopy because preparing and examining the specimen takes time.
Minor bleeding can sometimes occur where tissue is collected. Significant complications are uncommon, but patients should follow their discharge instructions and contact their medical team if they experience severe or worsening abdominal pain, fever, dizziness, heavy rectal bleeding, or other concerning symptoms after the procedure.
What Do the Biopsy Results Mean?
A normal biopsy means the sampled cells did not show the abnormalities being evaluated. This result can still be useful because it helps narrow the possible causes of a patient’s symptoms.
An abnormal result may identify inflammation, microscopic colitis, changes related to inflammatory bowel disease, an adenomatous or serrated polyp, dysplasia, or cancer. The meaning of a finding depends on the tissue type, its location, the patient’s symptoms, and other test results.
The physician will explain whether the result requires treatment, monitoring, another test, or a follow-up colonoscopy. Pathology findings should always be interpreted as part of the patient’s complete clinical picture.
Should You Visit a GI Clinic or Colorectal Surgeon?
At the Center for Colorectal Disease of Arizona, our colon specialist can evaluate symptoms and recommend appropriate care. Our colorectal surgeon provides diagnostic and surgical care for conditions affecting the colon, rectum, and anus. Contact us to schedule a colonoscopy or visit our GI clinic at one of our Phoenix-area locations.