Colonoscopy: Risk Versus Benefit

Colonoscopies are used to screen for colon cancer and remove suspicious lesions. They can be useful for finding cancer, but there are risks involved too. Complications and adverse effects may include pain, infection, blood loss, colon perforation, heart problems, and reactions to sedative medications like breathing problems, low blood pressure, and slowed heart rate.

A study published in the Archives of Internal Medicine found that serious side effects were not uncommon after colonoscopy. Researchers concluded that 1 percent of patients went to the emergency room within 14 days of the procedure. They also found that adverse effects were seriously under-reported. After 6,383 endoscopies and 11,632 colonoscopies, there were 134 trips to the emergency room and 76 hospitalizations but physicians only reported 31 complications.

The US Preventive Services Task Force recommends colonoscopy screenings for adults every 10 years beginning at age 50, but age shouldn’t be the only factor in determining screening recommendations.

Like any medical procedure or treatment, it’s important to weigh the risks and benefits. And when it comes to colonoscopy, some people benefit more than others.

A published in the Annals of Internal Medicine found that people with certain medical conditions are much more likely to have serious side effects after colonoscopy. They include:

  • Stroke
  • Chronic obstructive pulmonary disease
  • Atrial fibrillation
  • Congestive heart failure
  • Polypectomy (previous removal of polyps) 
  • More than one medical condition

Individuals who benefit the most from colon cancer screening are those who have the highest risk. These include:

  • Older adults (the older we get, the greater the risk)
  • African Americans
  • People who eat a low fiber diet
  • Sedentary individuals
  • People with a history of inflammatory bowel disease 
  • Obese and diabetic individuals 
  • People with a history of colorectal cancer or polyps
  • Individuals who have undergone radiation therapy directed at the abdomen (as part of cancer treatment, for example)
  • People who smoke cigarettes and drink alcohol
  • Individuals with inherited genetic syndromes like familial adenomatous polyposis and hereditary nonpolyposis colorectal cancer (also known as Lynch syndrome)
  • Anyone with a family member who developed colon cancer before the age of 60

So what’s the bottom line?

The benefits of colonoscopy screening, once every 10 years between the ages of 50 and 75, probably outweigh the risks for people who have a high risk of colon cancer.

The risks probably outweigh the benefits for adults after the age of 75 and for anyone with a history of stroke, atrial fibrillation, chronic obstructive pulmonary disease, congestive heart failure, or polyp removal.


Leffler DA et al. The incidence and cost of unexpected hospital use after scheduled outpatient endoscopy. Archives of Internal Medicine. 2010 Oct 25;170(19):1752-7.

Warren JL et al. Adverse events after outpatient colonoscopy in the Medicare population. Annals of Internal Medicine. 2009 Jun 16;150(12):849-57, W152.

Zauber AG et al. Evaluating test strategies for colorectal cancer screening: a decision analysis for the U.S. Preventive Services Task Force. Annals of Internal Medicine. 2008 Nov 4;149(9):659-69.

Leave a Reply

Your email address will not be published. Required fields are marked *