How a Colon Biopsy Is Performed

A colon biopsy is an exam that tests tissue samples from your colon. The healthcare provider is looking for abnormal tissues, such as cancerous or pre-cancerous cells. Keep in mind that just because your practitioner ordered a biopsy does not mean you have cancer.

under the microscope


Your healthcare provider found an irregularity in one of your colon cancer screening exams. The only way to definitively tell if the abnormality is cancerous is by extracting the tissue and taking a look at it under a microscope.

If abnormalities were found during a sigmoidoscopy or a colonoscopy, the healthcare provider probably extracted tissues during that same test. If irregularities (tumors, masses, blood in stool) were found during another screening test (double-contrast barium enema or fecal occult blood tests), you will be scheduled for a colonoscopy.

CT-Guided Biopsy vs. Colonoscopy

There are different approaches to the biopsy procedure which are dependent on where the irregular tissues were found. The most common way to obtain a biopsy of the colon is through a colonoscopy. However, if your healthcare provider found abnormalities on computed tomography (CT) scan that was not isolated in the colon, he or she may order a CT-guided biopsy.

A CT-guided biopsy also called a needle or CT-guided needle biopsy is completed in the CT room at the hospital or clinic. This type of biopsy is most frequently ordered when masses are found outside of the colon, including those in the lungs, liver, or pelvis.

The healthcare provider uses the CT scanner to pinpoint the abnormal area, inserts a needle into the mass in question, and extracts tiny tissue samples. You can go back to work the same day, won’t need sedation, and the entire process takes about one hour.

If the irregular tissues are confined to your colon, your healthcare provider will order a colonoscopy and take the biopsy during that procedure. During a colonoscopy, a lighted probe, called a colonoscope, is inserted through the rectum and snaked up the colon to visualize the interior. This flexible probe also allows the passage of specialized instruments that can retrieve (clip) a sample of tissue from your colon for the biopsy.


The colonoscopy preparation requires a complete bowel preparation prior to the procedure. Your healthcare provider may order a combination of liquid laxatives, suppositories, or an enema to cleanse the inside of your colon.

This cleansing procedure makes the lining of your colon visible by flushing out fecal matter and fluids in the large intestine. Talk to your healthcare provider if you have diabetes or take prescription medications, especially blood thinners, as your practitioner may have special orders for you prior to the exam.

Complications and Risks

Like any medical procedure, a colon biopsy is not devoid of risks. However, if colon cancer is present, the sooner you can begin treatment the better. Your healthcare provider will discuss the risks and benefits with you before the procedure.

Be sure to ask questions if the procedure details are not clear. The potential risks of a colon biopsy (with a colonoscopy) include:

  • Bleeding
  • Infection
  • Bowel perforation
  • Hospitalization
  • Postpolypectomy syndrome
  • Failed colonoscopy
  • Complications from weaning off of blood thinners prior to the exam
  • Complications from anesthesia
  • Non diagnostic biopsy

If you have a complex medical history or are elderly, your risk factors may increase. Discuss any prescription or over-the-counter medications with your healthcare provider prior to the procedure. A nurse or staff member from the hospital or clinic may call you to review instructions prior to your procedure.

Post-Procedure Follow-Up

In all likelihood, you will be sedated for the colonoscopy and biopsy; therefore, you shouldn't feel a thing. Following the procedure, you will be taken to a recovery area, where the staff will monitor you until you are awake and alert.

Due to the sedation, you will not be allowed to drive yourself home, even if you feel up to it. Your judgment is considered officially impaired for 24 hours following sedation (don’t sign any legal documents either).

Also, the air is inserted into your colon during the procedure, which may cause some cramping and passing gas. Do not hesitate to contact your healthcare provider if you develop a fever, shaking, chills, abdominal pain, dizziness, or notice blood in your stools following the biopsy.

Getting the Results

Immediately following your biopsy, the tissue sample is shipped off to the pathologist. A pathologist is a special medical doctor who examines tissues and blood under a microscope.

He or she will need time to examine your tissue sample thoroughly and will then construct a pathology report. The report describes whether the tissues obtained were normal or cancerous and will help your healthcare provider determine the staging and grade of your cancer.

Preferably before the procedure (as you may not remember afterward), ask your healthcare provider when you can expect results. He or she will be able to give you a ballpark figure and encourage you to make a follow-up appointment.

Once your healthcare provider receives your biopsy result from the pathologist, he or she will call you. If you do not already have an appointment to discuss these results, one will be scheduled for you at this time.

The healthcare provider will want to discuss your results in person, not over the phone or by email. Although the wait may produce some severe anxiety, it is better to sit down and talk with your practitioner about results face-to-face.

The Pathology Report

Your healthcare provider has a medical background and training to explain your pathology report to you. The pathologist’s report will include:

  • Where the lesion(s) were located within the colon
  • Histology, or the type of cells found, such as normal (benign) or malignant (cancerous). If malignant, the report will display the cancer type (adenocarcinoma is the prevalent colon cancer type).
  • Grade, which explains how mutated the tissues are (are they somewhat similar to regular colon tissue, not identifiable at all, or some grade in between) and is used to stage your cancer.
  • Invasion, which applies to tissue taken during surgery for colon cancer and helps determine how far cancer spread into healthy tissues.

Do not hesitate to ask your healthcare providers questions at any point along the way. The medical professionals are there to assist you.

8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Kagueyama FM, Nicoli FM, Bonatto MW, Orso IR. Importance of biopsies and histological evaluation in patients with chronic diarrhea and normal colonoscopies. Arq Bras Cir Dig. 2014;27(3):184-187. doi:10.1590/S0102-67202014000300006

  2. National Cancer Institute. Tests to detect colorectal cancer and polyps.

  3. American Cancer Society. Types of biopsies used to look for cancer.

  4. Rex DK, Schoenfeld PS, Cohen J, et al. Quality indicators for colonoscopy. Gastrointest Endosc. 2015;81(1):31-53. doi:10.1016/j.gie.2014.07.058

  5. Ahmed M. Blood thinners and gastrointestinal endoscopy. World J Gastrointest Endosc. 2016;8(17):584-590. doi:10.4253/wjge.v8.i17.584

  6. Fisher DA, Maple JT, Ben-Menachem T, et al. Complications of colonoscopy. Gastrointest Endosc. 2011;74(4):745-752. doi:10.1016/j.gie.2011.07.025

  7. U.S. Department of Health and Human Services, National Institute of Diabetes and Digestive and Kidney Diseases. Colonoscopy.

  8. National Cancer Institute. Pathology reports.

Additional Reading
  • American Society for Gastrointestinal Endoscopy. (2012). Colonoscopy.

  • National Cancer Institute. (May 2011). Chemotherapy Side Effects: Appetite Changes.

  • American Cancer Society. American Cancer Society's Complete Guide to Colorectal Cancer. Clifton Fields, NE: American Cancer Society.
  • Lange, V. (2009). Be a Survivor. Colorectal Cancer Treatment Guide. (4th ed.). Los Angeles: Lange Productions.
  • Levin, T.R., Zhao, W., Conell, C., et al. Complications of Colonoscopy in an Integrated Health Care Delivery System. Annals of Internal Medicine; 145. 

By Julie Wilkinson, BSN, RN
Julie Wilkinson is a registered nurse and book author who has worked in both palliative care and critical care.