When to Ditch a Colonoscopy: A Definitive Guide

Colonoscopy is a medical procedure that allows doctors to examine the colon and rectum closely. It is an important tool to detect and prevent colorectal cancer. However, not all colonoscopies are necessary or appropriate for everyone. In this article, we will discuss when to ditch a colonoscopy, based on different situations and conditions.

Age Matters

The standard recommendation for colonoscopy is to have the first one at age 50, and then every 10 years after that. However, this guideline applies to individuals with average risk. If you have a family history of colorectal cancer or other risk factors, you may need to start earlier and have more frequent screenings.

Family History

If any of your first-degree relatives (parents, siblings, or children) have been diagnosed with colorectal cancer, you are at higher risk, and should have your first colonoscopy at age 40 or 10 years before the age of diagnosis of the youngest affected relative, whichever comes first. If the colonoscopy is negative, you should repeat it every 5 years.

Personal History

If you have had a history of colorectal cancer, adenomas (pre-cancerous polyps), or inflammatory bowel disease (such as ulcerative colitis or Crohn’s disease), you need to have more frequent colonoscopies, based on the severity and extent of the condition. Your doctor will recommend the appropriate schedule, which may range from 1 year to 5 years.

Health Conditions

There are some health conditions that may affect your ability to undergo colonoscopy, and may make it unnecessary or risky. These include:

  • Severe heart or lung disease, which may make it hard to breathe during the procedure or tolerate the anesthesia.
  • Bleeding disorders, such as hemophilia or thrombocytopenia, which may increase the risk of bleeding during or after the procedure.
  • Pregnancy, especially in the first or third trimester, which may harm the fetus or cause premature labor.
  • History of allergic reactions to the sedatives or other medications used during colonoscopy.

Symptoms and Signs

Some symptoms or signs may indicate the need for a colonoscopy, while others may suggest the need to postpone or cancel it. These include:

Red Flags

These symptoms or signs may indicate the presence of colorectal cancer, or other serious conditions that require immediate attention:

  • Blood in the stool or rectal bleeding, which may be bright red or dark and tarry.
  • Change in the frequency or consistency of bowel movements, such as diarrhea or constipation.
  • Abdominal pain, cramps, or bloating, which may be severe or persistent.
  • Unexplained weight loss or fatigue, which may be a sign of advanced cancer or anemia.

If you have any of these symptoms or signs, you should not postpone or cancel your colonoscopy, but rather seek prompt medical evaluation and treatment.

Yellow Flags

These symptoms or signs may indicate other benign or minor conditions, but may still affect the quality or safety of colonoscopy, and require further evaluation or management:

  • Fever or infection, which may increase the risk of complications or affect the accuracy of the test.
  • Mild dehydration, which may make it harder to drink the prep solution or to tolerate the fasting period before the test.
  • Anxiety or fear of the procedure or the results, which may affect the cooperation or comfort of the patient.

Preparation and Follow-up

Colonoscopy is an invasive procedure that requires adequate preparation and follow-up to ensure its efficiency and safety. If any of the following issues arise, you may need to reschedule or repeat the test:

Prep Problems

The prep solution is a liquid that cleanses the colon and makes it easier to detect any abnormality. Failure to complete the prep may compromise the accuracy and reliability of the test, and require repeating it. Common problems include:

  • Nausea, vomiting, or abdominal discomfort, which may make it hard to drink or retain the prep solution.
  • Non-compliance with the instructions, such as drinking fluids or eating solids during the fasting period, or stopping certain medications without consulting the doctor.
  • Digestive disorders, such as gastroparesis or diverticulitis, which may delay or inhibit the absorption or passage of the prep solution.

Procedural Complications

Colonoscopy is generally safe, but may cause some minor or major complications, such as:

  • Perforation or puncture of the colon, which may require surgery or hospitalization.
  • Bleeding or hematoma, which may require blood transfusion or endoscopic treatment.
  • Allergic or adverse reaction to the medications or materials used during the procedure.

If any of these complications occur, your doctor may recommend cancelling or postponing the colonoscopy, and give you appropriate treatment.


Colonoscopy is an important screening tool for colorectal cancer, but may not be necessary or appropriate for everyone. Age, family history, personal history, health conditions, symptoms, and preparation and follow-up issues all play a role in deciding when to ditch a colonoscopy. You should consult your doctor and discuss your individual situation and risks before scheduling or cancelling a colonoscopy.

Frequently Asked Questions

Here are some common questions people ask about when to cancel a colonoscopy:

  • Q: What happens if I cancel or miss my colonoscopy?
  • A: It is best to reschedule it as soon as possible, unless there is a serious or urgent reason to postpone or cancel it, such as the presence of red flags or health conditions that make it unsafe or unnecessary. Colonoscopy is the most effective way to detect and prevent colorectal cancer, and delaying or avoiding it may increase your risk of developing or dying from the disease.
  • Q: Can I have a colonoscopy if I am allergic to the prep solution?
  • A: You should inform your doctor about any allergies or intolerances you have before the procedure, and discuss alternative options, such as different types of preps or medications. In some cases, you may need to undergo a different type of imaging test, such as computed tomography (CT) colonography or flexible sigmoidoscopy, instead of colonoscopy.
  • Q: What if I am too anxious or scared to undergo colonoscopy?
  • A: You should talk to your doctor about your fears and concerns, and ask for support and guidance. Your doctor may recommend using relaxation techniques, such as deep breathing or visualization, or prescribe medications or therapies that can help you feel more comfortable and confident. You may also ask to have a friend or family member accompany you during the procedure, or to have sedation or anesthesia to help you relax.
  • Q: What if the doctor finds something abnormal during the colonoscopy?
  • A: If the doctor finds a polyp, a growth, or other abnormality during the colonoscopy, he or she may remove it or take a biopsy (a small tissue sample) for further examination. Depending on the nature and size of the abnormality, you may need to repeat the colonoscopy sooner than the standard interval, or undergo additional tests or treatments.


  1. National Comprehensive Cancer Network Guidelines. Colon Cancer Screening. Version 2.2021. Accessed on 08/15/2021. https://www.nccn.org/professionals/physician_gls/pdf/colorectal_screening.pdf
  2. American Society for Gastrointestinal Endoscopy Guidelines. Colorectal Cancer Screening and Surveillance. Version 3.2021. Accessed on 08/15/2021. https://www.asge.org/docs/default-source/default-document-library/asge-guidelines-colorectal-cancer-screening-surveillance.pdf
  3. Centers for Disease Control and Prevention. Colorectal Cancer Screening Tests. Accessed on 08/15/2021. https://www.cdc.gov/cancer/colorectal/basic_info/screening/tests.htm

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