Patricia Yarberry Allen, M.D. is a Gynecologist, Director of the New York Menopause Center, Clinical Assistant Professor of Obstetrics and Gynecology at Weill Cornell Medical College, and Assistant Attending Obstetrician and Gynecologist at New York-Presbyterian Hospital. She is a board certified fellow of the American College of Obstetrics and Gynecology. Dr. Allen is also a member of the Faculty Advisory Board and the Women’s Health Director of The Weill Cornell Community Clinic (WCCC). Dr. Allen was the recipient of the 2014 American Medical Women’s Association Presidential Award.

Dr. Patricia Yarberry Allen is a collaborative physician. This week, during Colorectal Cancer Awareness Month, she asks gastroenterologist Brian Landzberg to advise a patient inquiring about that notorious day-before-the-colonoscopy bowel prep.


Dear Dr. Pat:

“I am 57 years old and have not yet had a successful colonoscopy. I tried three years ago to do the dreadful preparation before the colonoscopy, but was told by the specialist that the procedure could not be performed because my colon was “not cleaned out.” I did everything that I was told to do, but it didn’t work. I certainly don’t want to see those nurses and that doctor again, because I am still embarrassed. I investigated doing a virtual colonoscopy, but my GP told me that my colon would still need to be cleaned out or that wouldn’t work either.

I have had sluggish bowel function for my entire life. I was given castor oil by my grandmother when I was a child. Is there a special way for people like me who have severe constipation to clean their colon out? I really need this test now, because my brother was just diagnosed with stage 3 colon cancer. He had constipation too and never had the test until he had real symptoms. Now he is seriously ill. He has begged me to get this done.



Dr. Pat Responds:

Dear Constance:

Everyone dreads the colon cleanout procedure. It is worse than the colonoscopy, because sedation is given for that procedure! I have asked Dr. Brian Landzberg, Assistant Attending Physician at New York-Presbyterian Hospital, to answer your question. Dr. Landzberg is the gastroenterology specialist on the Women’s Voices for Change Medical Advisory Board.

Dr. Pat



Dr. Landzberg Responds:

Dear Constance:

Thank you for your question. It is particularly timely and appropriate for March, Colorectal Cancer Awareness Month!

Why is a screening colonoscopy important? Because during this procedure we can remove precancerous lesions, known as polyps (Figure A), and thus, in the vast majority of cases, prevent incurable colon cancer from ever occurring (Figure B).  If you ask patients who have been through a colonoscopy, the vast majority will tell you that the preparation is the worst part of the experience. The procedure itself should be a comfortable and, believe it or not, pleasant experience, with the benefit of the excellent sedation medications available to us. You are precisely correct that the option of CT colonography, a.k.a. virtual colonoscopy, requires at least as thorough a bowel preparation. And if polyps were found, you would then have to take a second preparation and have a traditional colonoscopy to remove them.

Screenshot_3_21_13_8_26_AMFigure A: Colonoscopy photographs of a polyp removed with a cautery snare. © Brian R. Landzberg, M.D.

Colonoscopy of colon cancerFigure B: Colonoscopy photograph of colon cancer.  © Brian R. Landzberg, M.D.

The quality of the preparation is important: A poorly prepared colon is one in which polyps and small cancers can be missed. As difficult as it is for a gastroenterologist to tell a patient that his or her procedure could not be effectively completed, it is the right call to make if there is inadequate visualization. Too often I hear about procedures that were completed with poor visualization, when it was not made clear to the patient that the test was non-diagnostic, and important lesions could have been missed.

The question of what is the best preparation method is difficult to answer. There really is no “one size fits all” prep. For some, a given regimen will be excessive, while for others it will be inadequate.  For patients with a history of sluggish colon or who have the benefit of knowing they had an incomplete bowel preparation, I would recommend a two-day preparation. You should be on a clear liquid diet for two days before the procedure. I generally have such a patient take Dulcolax and a bottle of magnesium citrate two days before the procedure and then a combination of Dulcolax and a mixture of Miralax and Gatorade one day prior to the procedure. There are occasions when I have prescribed an even more vigorous prep than this.

Being able to customize a bowel preparation for a patient (based on his or her bowel habits, medications, tolerance of large volumes of liquid, and colonoscopic history) is a reason why I like to meet patients in the office to take a proper history and discuss the procedure before the colonoscopy day. I am aware that this is omitted in the majority of gastroenterology practices.

Get the colonoscopy done.  Certainly don’t be embarrassed. Spread the word of your brother’s painful lesson about colon cancer and you can help save lives!

FIGURE C: Myths About Colon Cancer Screening

Myth #1  Colon cancer mainly affects men.  WRONG!

Fact: Roughly equal numbers of men and women are diagnosed with colon cancer.

Myth # 2  Only people with a family history should worry about it. WRONG!

Fact: Almost 75 percent of colon cancer cases do not have a family history of colon cancer.

Myth #3  I don’t have symptoms so I don’t need to be screened. WRONG!

Fact: In early stages, colon cancer generally gives no symptoms or warning. When symptoms and signs such as bleeding, constipation and anemia develop, it is often too late to cure.  

Myth #4  Colonoscopies are uncomfortable and time consuming. WRONG!

Fact: The procedure takes 15-30 minutes, sedation makes this a painless test and you can resume normal activities the next day.

Myth #5   Colon cancer can’t be prevented or cured and it’s always deadly , so don’t bother looking for it.  WRONG!

Long-term follow up data from the National Polyp Study confirm that colorectal cancer death can be dramatically reduced by colonoscopy and polyp removal.   If colon cancer is caught at early stage, the five year survival is 90%

Myth #6 :  Age is irrelevant to getting colon cancer. WRONG!

Over 90% of colon cancer occurs in people over the age of 50, which is why that is the age we start general screening.   Some patients may need to start screening or surveillance  at a younger age if risk factors such as family history of colon cancer or inflammatory bowel disease are present



Brian R. Landzberg, M.D., A.G.A.F., is Clinical Assistant Professor of Medicine in the Division of Gastroenterology and Hepatology at the Center for Advanced Digestive Care, Weill Medical College of Cornell University, and Assistant Attending Physician, New York-Presbyterian Hospital. His particular areas of clinical interest are celiac disease, functional gastrointestinal disorders including constipation, diarrhea and irritable bowel syndrome, inflammatory bowel disease, gastritis, GERD and liver disease. He has published and lectured on these topics and maintains a very active clinical practice on the Upper East Side of Manhattan.

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  • Robin September 29, 2016 at 9:23 pm

    I have been searching the internet for info. from someone, ANYONE, who had an unsuccessful bowel cleanse and colonoscopy. I’m thrilled to have finally found someone else who has experienced this. Today, I underwent my SECOND unsuccessful colonoscopy. Took me 3 years to obtain the willingness to give it another try, went to a different doctor and, based on my prior experience, did a two-day prep. Again, the doctor was unable to perform the exam. I am so frustrated and although I want to have this exam performed and understand it’s import, I don’t know when, or how, I can bring myself to undergo that awful prep again….ugh….

    • Hope January 15, 2018 at 6:51 am

      I just had an unsuccessful prep as well. I did everything meticulously as prescribed, the low residue diet for days, the liquid diet starting at 1:00 pm the day before, the first half of the prep the night before (spent 4 hours back-and-forth to the restroom), up at 5:00 a.m. to do the send half of the prep (a few more hours of fun times), went for procedure, put to sleep, woke up, was told they could not do it as I was not cleaned out well at all. Wonderful. Now I have a different brand prep and am scheduled to go back in a week, and I’m afraid this one will fail too. The first was a PEG / eletrolyte prep, and this one is Bisacodyl pills two days before, and a split Magnesium citrate based prep. I think if this one doesn’t work, I may give up, despite my family history. I have now read that if you are prone to constipation, the PEG prep may not work, although the receptionist at the clinic told me it works for most of their patients.

  • Faylinn September 19, 2016 at 12:10 pm

    I have never seen colonoscopy photographs before, but I really appreciate you featuring them on this post. My husband keeps putting off going and getting this procedure done, but I don’t think that he realizes how real cancer can be fore him. If a polyp is removed, though, does that absolutely guarantee that cancer is gone entirely?

  • Patricia A Vitale June 18, 2015 at 8:12 am

    This is a very informative website. I am going to be 72 years old this year and I am going to have my first colonocopy next month. I am a wreck. Any tips for me?

  • Susanna Gaertner April 1, 2013 at 3:46 pm

    Because I wanted to watch the actual procedure, my doc was willing to put in ports for both brief and (the more customary) twilight sedation. I was able to watch the whole thing with just a burst of medication when the camera turned the two corners; it was fascinating!
    I know this isn’t for everyone, but if you are healthy and your doctor is willing to try, I strongly recommend the option of watching this unique view of your insides!

  • hillsmom March 26, 2013 at 11:36 am

    Ok, I’ve thought long and hard about commenting on your most excellent article, mostly because of embarrassment. However, perhaps it will help to spread the word around for others who feel the same way, so here goes.

    I had the procedure a week ago yesterday, and just got the word this morning that the polyps were benign. Phew! I had put the procedure off for 5 years, because who wants to go through it, and all other rationalizations one can think of.

    The prep is definitely the WORST! In addition, now one is given Suprep Bowel Prep, but I was to use the directions from my Dr. and not the one on the package. This seems to be the “only game in town” when it comes to prep. It is listed as a third tier under my Medicare part D. Why is it so *&#$ expensive? it runs from $70 to $110 for 2 small bottles of (blech!) liquid and a plastic cup. Believe me I checked all around for prices. I think it used to be about $20, but can’t confirm. Please forgive mini-rant…