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Why I Won’t Get a Colonoscopy

The views expressed are those of the author and are not necessarily those of Scientific American.

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I recently visited a doctor for one problem, and, as doctors are wont to do, he recommended tests for completely unrelated problems. My hearing has seemed muffled lately, so I wanted the doctor to peer in my ears. He said my ears looked fine; I’m probably just experiencing normal, age-related hearing decline. (Delayed effects, no doubt, from sitting in the front row during a Jimi Hendrix concert in 1968.)

The doctor asked me when my last check-up was. Five years ago, I said, after I got a sports hernia playing hockey, but I feel fine. He nonetheless recommended a blood test for high cholesterol and other potential problems, a PSA test for prostate cancer and maybe a screen for colon cancer. No thanks, I said coldly, and left his office. Little did he know he was talking to an anti-testing nut.

As I reported last fall, men are 47 times more likely to get unnecessary, harmful treatments—biopsies, surgery, radiation, chemotherapy—as a result of receiving a positive PSA test than they are to have their lives extended, according to a major study.

As for screening for colon cancer, a new study allegedly finds merit in colonoscopies, a nasty, expensive procedure in which a physician sticks a cable tipped with a camera and clippers up your butt and snips off suspicious-looking lumps on the wall of your bowels. The study, published in the New England Journal of Medicine, involved 2,602 patients tracked for up to 23 years after they had colonoscopies resulting in the removal of polyps. Twelve people in this group died of colon cancer, compared to an average of 25.4 people in the general population.

A New York Times editorial proclaimed that the study “ought to goad millions who are still ducking [colonoscopies] to get over their squeamishness.” The study ought to do no such thing. First of all, it was not a randomized clinical trial. The screened group might have been healthier to begin with than the non-screened group.

Second, the study looked only at death from colon cancer and not from all causes. The physician James Penston, a consultant to England’s National Health Service, argued in the British Medical Journal last October that all-cause mortality is a better measure of the value of screening, both because attributing cause of death can be unreliable and because screening itself can be harmful.

“Invasive procedures may have fatal complications, while overdiagnosis—that is, the identification and treatment of tumors that otherwise would have caused no disease—may also result in death,” Penston stated. According to Penston, meta-analysis of four randomized trials involving 300,000 people found that tests for bowel cancer did not reduce overall mortality rates.

Another analysis of British data on colon cancer, by the watchdog group Straight Statistics, concluded that screening 1,000 patients for 10 years will prevent two deaths from the disease. Meanwhile, colonoscopies lead to “serious medical complications” in 5 out of every 1,000 patients, according to a 2006 report in the Annals of Internal Medicine. Given these risks, my guess is that a rigorous examination of colonoscopies will find that their benefits do not outweigh their downside.

The New York Times, perhaps to offset its ill-considered editorial plug for colonoscopies on February 24, ran a rebuttal of sorts three days later from H. Gilbert Welch, a professor of medicine at the Dartmouth Institute for Health Policy and Clinical Practice and author of Overdiagnosed: Making People Sick in the Pursuit of Health (Beacon Press, 2011). Welch wrote:

“Screening the apparently healthy potentially saves a few lives (although the National Cancer Institute couldn’t find any evidence for this in its recent large studies of prostate and ovarian cancer screening). But it definitely drags many others into the system needlessly—into needless appointments, needless tests, needless drugs and needless operations (not to mention all the accompanying needless insurance forms). This process doesn’t promote health; it promotes disease. People suffer from more anxiety about their health, from drug side effects, from complications of surgery. A few die. And remember: these people felt fine when they entered the health care system.”

Now that’s a healer who adheres to the ancient precept: First, do no harm. The next time a doctor urges me to get unnecessary tests, I’m going to email him Welch’s essay.

Image courtesy Wikimedia Commons.


John Horgan About the Author: Every week, hockey-playing science writer John Horgan takes a puckish, provocative look at breaking science. A teacher at Stevens Institute of Technology, Horgan is the author of four books, including The End of Science (Addison Wesley, 1996) and The End of War (McSweeney's, 2012). Follow on Twitter @Horganism.

The views expressed are those of the author and are not necessarily those of Scientific American.

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  1. 1. mowensmd 11:39 am 03/12/2012

    I understand your concerns about the lack of randomized, controlled data. Unfortunately, it is hard to come by for prevention of death over a long period of time for many reasons. You also could include concerns about lead-time bias for all screening tests. But colonoscopy is not a screening test. It is a prevention. And RCT’s do show prevention of getting the cancer. True, we have not yet demonstrated that not getting the cancer keeps you from dying from it in a RCT, yet. But the NEJM article is very supportive this may be the case. I don’t think that the lack of randomization affects the outcome significantly enough to warrant your dismissal. There really is not much you can do to make a person healthy enough to change their colon cancer risk. So really, the health of a population is moot. Unfortunately the articles and statistics you quote or the link you provide are heterogeneous in comparison to your argument. First, a study of checking the stool for blood is not the same as (and has much worse data compared to) colonoscopy. Also, be extremely careful comparing data between US and non-us providers, or between gastroenterologists and non-gastroenterologists. The quality of the colonoscopy is one significant factor for the reason prevention rates have varied between Canada, surgeons, and otherwise. Second, the rate risks of the procedure you provide is for Kaiser patients. Kaiser has previously decided not to perform colonoscopy for prevention, instead preferring to save money until data is so unavoidably conspicuous they have only recently been forced to do so. (though interestingly, the strength of data required for Kaiser to decide to save money is a different standard) In this article, all the colonoscopies were for symptomatic patients. These patients have significant risk factors for compliction. (large bleeding lesions, inflammation of the colon, etc.) In reality, the risks from colonoscopy for any complication are likely less than 1/3-5000. Risks of serious complications 1/5-10,000. In comparison, recall that the risk of colon cancer is about 1/17 -20 as you mention. However, the stage it is diagnosed is extremely important. If diagnosed when bleeding (i.e. you check for blood in the stool you will only catch things already advanced and bleeding), you will have a more advanced disease. The likelihood you will die from cancer if you get it is second only to lung cancer in the US.

    I agree there is an enormous amount of waste in the push to suggest problems and treatments for them. Nowhere is this more apparent than in the world of supplements, naturuceuticals and naturopathy. But prevention of a number of conditions including diabetes, high-blood pressure, obesity and colon cancer may be the strongest evidence we have for lowering disease and costs from them.

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  2. 2. Jayr109 1:36 pm 03/12/2012

    I don’t have time to go into all the ways this article is flawed, but PLEASE, anyone reading this – GET A COLONOSCOPY. There’s a reason everyone with a medical degree and two neurons worth of common sense recommends it.

    And to the self-proclaimed “anti-testing nut”: I don’t care what tests you do or don’t get. It’s your (likely shortened) life to live. But when you write articles encouraging people to avoid tests that WE KNOW SAVES PEOPLE FROM PREVENTABLE CANCER then you cross the line from being a harmless idiot to being a reckless attention seeker and you’re going to get people hurt.

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  3. 3. Gerrly 2:07 pm 03/12/2012

    Author has his BA in English and MS in Journalism.

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  4. 4. jgrosay 2:43 pm 03/12/2012

    It was shown many years ago that Colorectal Cancer Screening saves lives, and as of today, Colonoscopy or some kind of imaging technique will be part of the screening process sooner or later. Complications of the Colonoscopy procedure and seriousness of complications increase as patient’s age increases, but probably that’s all. Your decission puts you at risk, almost certainly. Salut +

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  5. 5. 3:09 pm 03/12/2012

    What you do or don’t do, is up to you. I stopped caring when I read “he was talking to an anti-testing nut” in the article.

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  6. 6. Mark Pine 3:18 pm 03/12/2012

    Horgan is right. The study that the NYT cited is not a randomized trial. It uses generally population stats as the concomitant control. That’s good for almost nothing, except possibly ballpark estimates, and it is completely inadequate for doing a statistical comparison.

    The only quibble I have is the statement about 10 years of screening. For most people, that may be only two exams, one every five years, not so awful. I’ve had several colonoscopies because of another condition. The procedure itself isn’t so awful, and they are often done with sedation. It’s actually the prep (emptying out) that the most unpleasant part.

    As is common in our fee-for-service US medical system, there is a constituency that makes money doing colonoscopies, particularly the gastroenterologists who do them. If America eventually moves to a coordinated-care health care system, in which doctors are paid by the patient rather than the procedure and are rewarded for health outcomes, the medical profession will be motivated take a serious look at colonoscopies and other screening tests, to see which ones do more good than harm.

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  7. 7. Shecky R. 3:32 pm 03/12/2012

    I wholly support John’s call that colonoscopies ought not be nearly as automatic a decision as the medical community makes it out to be. Of course, they can save lives… duhhh, so can wearing a football helmut while driving (or better yet, avoid driving a car altogether), so can a 1000 other costly, medically unnecessary, (even dangerous) procedures if we do them across the board to enough people, but saving lives (believe it or not) is NOT the sole driving purpose of medicine, and the statistics on colonoscopies are, for a number of reasons, very rough, anyway.
    Moreover, long term side effects/dangers of the procedure are not truly known (indeed, it’s not clear they’re even being studied much), and one of the most dangerous parts of the whole procedure for some individuals (which for some reason doctors don’t much discuss) is not the colonoscopy itself but the 24-48 hr. laxative prep that precedes it. And, like most tests, they catch only a percentage of active cancers — you can leave being told you’re healthy, when in fact you do have colon cancer.
    There are a great MANY factors to consider before getting a colonoscopy; doing so on no other basis than your age is not necessarily wise.

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  8. 8. PeterT 5:52 pm 03/12/2012

    I had a good friend who postponed and postponed his colonoscopy…’till it was too late.

    He’s dead at 65. Colon cancer went to his liver.


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  9. 9. ironjustice 9:01 am 03/13/2012

    “Veterans test positive for hepatitis after colonoscopies”

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  10. 10. rock johny 1:06 pm 03/13/2012

    i had one once; they only got partway because there was a sharp bend the couldn’t safely navigate past…made me wonder how many times they force that hoobajoob up in there then pulling on all your guts on the way out. What harm can that cause? There are ligaments suspending your guts, right? Maybe they’re not that fragile…i don’t know. Anyone?

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  11. 11. DV111 4:28 pm 03/13/2012

    People forget that there is a difference between population studies, and YOU. There is no in-between when you are affected by a dread disease (you don’t get 28% cancer), and population studies only give you an idea of potential propensity toward a future problem depending on how you fall into the categories. So the only stat in the world that is worth anything comes down to the one describing you. Right now anti-testing nut seems OK. In the future, maybe he’ll continue to be OK… maybe not. Colonoscopies are really not all that bad- you’re out for most, if not all, of it, and you’re back on your feet in a few hours, tops. My own story- I would not be here writing this if I had put off my 50 year (standard) colonoscopy screen for colon cancer. The docs found a polyp that tested as a carcinoma in situ. This was a polyp that was ready to generate full-blow colon cancer. This was not “pre-cancerous”; this was cancer that had not left the polyp yet. Luckily, the procedure found the suspicious polyp, the doc cleanly removed in, with clean margins, and with a few follow-ups, everything was deemed OK. No doubt in my mind- the procedure and the GI staff saved my life. I had no symptoms, was reasonably active before, etc., etc. So if anti-test nut decides he doesn’t need the test, OK. But the biggest problem for health care is how many people depend on the system for the more expensive treatments (read chemotherepies,etc.) after they are sick rather than being proactive for their own well-being.
    Good luck buddy!

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  12. 12. Mark Pine 9:17 am 03/15/2012

    The NEJM today reports the results of a European randomized controlled trial of PSA screening every 4 years, among a quarter million men aged 55-69 and 130,000 tests, with 10-11 years of follow-up. The results indicate a 21% reduction mortality rate from prostate cancer in the screened group (29% reduction when non-compliance is figured in). Relative risk reduction was 39%, comparing mortality rates in screened and non-screened groups. About 1 man fewer died among 900-1000 men screened and about 30-35 men diagnosed with prostate cancer. The effect of screening on reducing prostate cancer mortality was significant at all ages of men screened. But the effect on reducing all-cause mortality was not significant for men over 70.


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  13. 13. Mark Pine 9:40 am 03/15/2012

    Looking over the numbers in the first comment, some may not be quite right. – Sorry. Data at

    In an accompanying editorial, a North American public health physician wrote: “We are left with an unsatisfactory situation, in which many practitioners will think there are insufficient data to recommend abandoning PSA screening for prostate cancer. … An intensification of PSA screening [in the US] would be unwise, and I think it would be advisable to follow the preliminary recommendations of the U.S. Preventive Services Task Force.

    USPSTF gave PSA screening a grade of D, discourage screening, in 2011.

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  14. 14. Thonictoo 7:51 pm 03/18/2012

    Here’s a copy of my letter to Mr. Horgan:
    Mr. Horgan,

    I read your remarks about colonoscopies being unnecessary and I will add a bit of information for your personal consideration.

    October 13, 2001 I submitted to my first ever colonoscopy, as did my wife the same day, due to the badgering of one of my sons. I had just turned 71 at the time. My wife got a clean bill of health. I was not so fortunate. I was found to have a belly full of stage 4 cancer with multiple malignant lesions inside and outside the colon. While I was still cleaned out from the exam prep, I was rolled into surgery the next morning and had my entire colon and related parts removed followed with installation of an ileostomy. That event was followed by 6 months of chemo, 26 radiation treatments and (at the suggestion of the radiation oncologist) a genetic study. The genetic study was to determine if there might be good reasons for my sons, daughter and 12 grandchildren to be super cautious in checking for colon cancer as they lived out their lives.

    My surgery was followed with periodic check-ups by my oncologist with intervals that stretched out to annual visits. The compelling item in those check-ups was the reading of my CEA score produced from a blood sample. CEA is a marker that shows the presence of colon cancer cells in the body and a satisfactory reading is “5″ or less. I remained under that point for five years after surgery and was pronounced “cancer free” which was a great relief. Even though the oncologist said it was unnecessary, I decided to continue the annual check-ups which really only amounted to giving a blood sample to take a look at the CEA. My check-up in December of 2010 turned up a CEA of 26! It was checked again and turned up as 32! That was followed by a scan which showed a golf-ball size tumor in the left lobe of my liver and a biopsy said it was malignant. The colon cancer had metastasized after having been tamped down by my immune system for several years which astonished the oncologists. I had surgery in April 2011 to remove the liver’s left lobe with its imbedded tumor, followed that event with a few chemo infusions and now everything looks OK. Once again I’m “cancer free”.

    The point of this narrative is that if I had not had the colonoscopy 11 years ago, in spite of no other indications, I would have been dead probably 10 years ago. In the meantime I have enjoyed seeing my grandchildren mature, including 4 brothers graduate from Dartmouth. My wife and I live a productive life in Texas thanks to my having had a colonoscopy 11 years ago. My grandchildren have been alerted to the potential for genetic contamination and take necessary precautions including colonoscopy exams beginning at age 25. I have since been told repeatedly that colon cancer is the only cancer that is 100% curable if detected early. That means by colonoscopy. Take heed.


    Tom Nicholson
    Fort Worth, TX

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  15. 15. PalMD 7:17 am 03/19/2012

    This is the same guy who wrote “The End of Science”. Also, not a public health expert or doctor. But he may have a small point about colonoscopies. A small nearly irrelevant one. But he lumps all “testing” into the same category which is insane. PSAs are not colonoscopies are not cholesterol levels.

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  16. 16. Sprockets 9:09 pm 08/24/2012

    I agree wholeheartedly. Colonoscopies only became “necessary” when i surance companies started paying for them. Coincidence?

    In Europe, where procedures are vetted on a cost/benefit basis, colonoscopies are performed only when certain specific symptomatic criteria are met. This makes perfect sense.

    There is also some very troubling data that suggests that removing growths which are not cancerous (and most of us have them) can cause the site to become cancerous. There are also very real risks with the procedure, and those should be factored in to the decision to undergo a colonoscopy.

    Thank you for addressing this subject.

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  17. 17. EEBAust 11:24 pm 11/19/2012

    There is a lot of pressure to screen, from the programs, doctors and relatives & friends. My husband and I are being pestered by close relatives to have colonoscopies, but we’re not satisfied by the evidence. So many people just screen like it’s a no brainer and of course, are frustrated by our reluctance to screen, “how could you take such a risk with your life?”…most of these people have never looked into the actual benefits and harms of testing….they just screen.
    Of course, it’s a no-win situation, if you don’t screen and get colon cancer you get the “I told you so” remarks and if you screen and end up harmed…it’s put down to bad luck, you had to screen so you were just unlucky.
    I think we’ve decided not to screen…we’re not high risk anyway, my MIL and my mother both got bowel cancer, but they were older when they were diagnosed…72 and 78.
    My SIL believes if her mother had screened, she’d still be alive today…possibly but, colonoscopies don’t pick up all cancers/polyps.
    The pressure to screen is insidious, so often the information we get is biased or incomplete. I’ve declined other screening programs and have faced shock/anger/concern/scolding/impatience from doctors and others, almost like women have no choice, we’re expected to file in like ignorant sheep. I know many women who’ve been harmed and distressed by false positives and over-treatment. I at least know what I’m refusing, while most pro-screeners have no clue what they’re accepting, they’ve never researched the area and just follow recommendations.
    Doctors often assume consent (especially with women) and can be quite rude if you decline…some even refuse to accept you as a patient or use coercion to force you to screen. The latter still happens in the States and it happened in Australia as well until about 15 years ago. I don’t believe doctors should receive target payments for cancer screening, or they should at least disclose this potential conflict of interest.
    I believe my health is better and my life happier because I’ve made informed decisions to refuse screening tests…and I had to do my own research, the “information” provided was heavily biased in favour of screening. I think powerful vested and political interests exist in screening, especially women’s cancer screening…it’s a minefield to be negotiated.
    I enjoyed reading this article…couldn’t agree with you more.

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  18. 18. fschwall 8:08 pm 04/1/2013

    How did Scientific America every allow this guy to darken their door? They should change their name to UnScientific America. He has no idea what he is talking about. I guess he would have advised me to not get a colonoscopy at age 48. That would have worked out well. Then I would not have known I had a tumor that was about to block my colon plus 14 cancerous lymph nods. I could have avoided getting chemo treatments as well. The only problem would be that I’d be dead. Don’t listen to this guy get a colonoscopy. It is easy and can save your life. By the way John it sounds like you might have gotten hit in the head a few times by a hockey puck – but I am sure you think a visit to your doctor would be a waste of your time.
    Frank Schwall

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  19. 19. klhoush 2:33 pm 01/14/2014

    My doctor keeps bullying and badgering me to get a colonoscopy but when asked about the risk associated with the procedure just dismisses me with a wave of the hand.

    What are the ACTUAL risks of the procedure? A bit of searching on the web reveals some risk at every stage of the procedure.

    It appears that for every person saved from colon cancer, one healthy person will die from complications due to colonoscopy and 5 others healthy people will need further treatment.

    I don’t like those odds very much.

    Kurt Housh
    San Anselmo, CA

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  20. 20. RichfromVegas 6:16 am 03/24/2014

    At age 53, I had a prostate biopsy in May of 2009 at the insistence of an urologist, due to a lump on my prostrate. Two days later I went into system wide, massive bacterial septic shock. I nearly died, spent four days in ICU and never really recovered. The infection specialist was amazed that I survived and warned me I could never again have any invasive procedures, especially a colonoscopy; not even have my teeth cleaned. The bacteria in my blood was so resistant, it took all the tools in their arsenal to save me. As a result, the bacterium which now remains in my body is super-resistant. If it ever gets back into my circulatory system, I’m done, there is little or nothing which can be done for me from here on out.

    It is amazing how many doctors try to convince me I really need a colonoscopy, even after I remind them of the biopsy incident. The irony was I did not have prostate cancer, but I do have a damaged heart, as a result of this one test and now battle a multitude of other issues on a daily basis.

    My cardiologist wants me to have an angiogram because he “thinks” I “might” have a blockage, which apparently showed up after a chemical stress test.

    I have so far declined due to the potential risk. As far as the angiogram goes, does anyone have an opinion on this; pros verses cons?

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  21. 21. Hillman321 9:28 pm 12/19/2014

    I had my first colonoscopy for my 70th birthday. I was found to have Stage 3 colon cancer with one lymph node involved. I had a section of my colon removed.

    If I had not had the colonoscopy things would be a lot different for me now.

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  22. 22. Justinerealtalk 6:58 am 01/19/2015

    This article makes me sick! I am now 26. The first time I ever got a colonoscopy was a month after I turned 25. I have had 7 total colonoscopys in that time, and one extended colonoscopy, along with 10 endoscopys, yes if you do the math I have had more colonoscopys in less than a year than most people have in a life time. I am living proof that these tests can and will save or help you save your life! I had an extended colonoscopy a procedure not normally done on anyone under the age of 50 because of the risks. But it is the only reason I am alive today! I have a disgusting family history of colon cancer and I was told by my doctors at the Mayo clinic that they where not sure what was wrong with me. That my internal bleeding was so bad I could bleed out in my sleep. In my mind the risks do not outweigh the good that can come from these tests! If you would like to allow yourself to die from something you could prevent listen to this man that is far my senior that sounds like a scared little boy. Any other test that was done in that time couldn’t tell them what was wrong with me. And the extended was my last shot before exploratory surgery. I had abdominal surgery to remove part of my small intestines and have been extremely thankful for the tests provided. If these tests would not be available I would be every parents worst nightmare and my mother would have had to bury me at the age of 25. It’s three days that you have to drink as what I call them lemon nasty coctail that tastes like shit, get the procedure, then feel gassy and bloated for a day. And your life may be saved! I would never in my life tell anyone to not go through with the procedure! Just think of how many I have done and no complications! Please don’t let someone scare you stupid, my grandmother that would be 83 now dyed of colon cancer at the age of 33. I never was blessed with her presence in my life, but if she was screened she may have been saved!

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  23. 23. trisoen 8:31 pm 03/6/2015

    Mr. Horgan, you’re an idiot, Sir. Your ignorance is costing lives because people may believe you.

    Do not listen to this fool, I had my first at 51, large polyp found, it was removed, just had my second follow up at 54, I’m good for five years. I was told three MAJOR colon cancers were diagnosed last week by this center — these routine terrible tests. They wouldn’t even have a chance without this test.

    Prep is uncomfortable, nothing you can’t survive. Just uncomfortable. Do it, and stay alive.

    You are dangerous Mr. Horgan. Please ignore this moron.

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  24. 24. GrannyMachine 10:28 am 04/10/2015

    Oh my G, John! I just came across this article and had to comment! I’m totally with you about colonoscopies! I nearly gave in in Jan.. Scheduled the prodedure, picked up the poison and waited. Changed my mind & cancelled (for the reasons you stated). In a momentary relapse, I called last month to reschedule. As I was speaking to the doctor’s assistant I told her I still had the poison so I didn’t need a new perscription. It came to light in that conversation, NOT the one in January, that I only have one kidney. To which she exclained, “Oh no, you can’t take that it will damage your kidney! We’ll have to give you a milder one!” To which I replied, “Oh really?! We’re done here. Have a nice day.” But that begs the question: If I had two kidneys, why would it NOT have damaged BOTH of them? I am 66 and in good health…just keep me the hell away from doctors and I may just stay that way!!!!

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  25. 25. jbg376 2:56 pm 04/27/2015

    This is all fine and dandy but the doctor is pressured to recommend these tests even if he didn’t think they were called for. Doctors are PRESSURED by their medical group, who in turn is pressured by….? So they have to follow policy. I personally think it’s criminal that they coerce healthy people into invasive “preventative” treatment. Oh, we’re just going to get the polyps out, meanwhile you have a bunch of open bleeding areas in your colon that now must heal, and also absorb stuff from feces that passes by it.

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