Search This Blog

Sunday, May 13, 2012

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.

1 comment:

Eliz52 said...

Nice to see some balance, we seem to be screening-crazy these days...women with no cervix (after a full hysterectomy for benign conditions) having pap tests is one example. There seems to be no respect for informed consent in women's cancer screening, we're expected to file in like ignorant sheep. I've rejected both cervical and breast cancer screening, the recommendation is to basically just do it, but my research made it possible to weight up the risks and actual benefits and make an informed decision. It seems many in medicine don't believe women have that right, that we can't "reasonably" decline testing.
American women are even routinely coerced into elective screening and excess, no birth control pills unless you agree to a pap test, (often annual = serious over-screening) a bimanual pelvic and breast exam. (and sometimes a recto-vaginal exam)
These exams are not evidence based, carry risk, and are not recommended in asymptomatic women of any age in the UK, much of Europe, Australia etc. The pap test is like the PSA test or colonoscopy, elective, and legally and ethically they require our informed consent. The only clinical requirements for the Pill is a blood pressure test and medical history.

I was content with my near zero risk of cervical cancer, rather than a 77% lifetime risk of referral for colposcopy/biopsy with the Australian program. (which seriously over-screens women leading to very high and hidden over-treatment rates).

More recently, I declined mammograms, the Nordic Cochrane Institute summary helped me there, "The risks and benefits of mammograms" is at their website, it should be given to every woman considering a mammogram. The evidence is concerning: about 50% of screen detected breast cancers are over-diagnosed, the fall in the death rate is mostly about better treatments, not screening, and the risks of screening exceed any benefit when you include women who die from heart attacks and lung cancer after treatments. (Professor Michael Baum's research - see:

So now the pressure starts with bowel cancer screening, although there's a LOT less pressure to have bowel screening. (even though it's much more likely than rare cervical cancer)
My mother had surgery for bowel cancer at 78 so apparently, that puts me in a slightly higher risk group. I know Dr Gilbert Welch is doing a randomized controlled trial comparing the FOBT with the more invasive colonoscopy. I look forward to the results. Anyway, I'll do my research and make an informed decision, but it's such a change to read something balanced from a doctor, rather than, "Get screened or die!"...

In my opinion this constant search for cancer is an unhealthy way to live. I think dealing with symptoms and living well is a better option. (decent diet, regular exercise, don't smoke, limit alcohol and red meat, keep an eye on stress levels etc.)
The benefits of screening and the risk of the cancer are usually exaggerated and the risks of testing never mentioned or played down, you wonder whether vested and political interests are the real winners with all of this screening.

Kind regards