In the last article, we covered how to retroflex the scope in the right colon. In this article, I will show you why someone would want to do such a thing. Let’s take this one step further: Should we do this routinely during every colonoscopy?

Simply put, sometimes the only way to physically get to whatever it is you need to reach, is to retroflex the scope in the right colon. Usually this is done to resect a polyp in a difficult location, such as the proximal (back) edge of a fold. In a previous article, I showed an example of using retroflexion in the right colon to remove the remaining pieces of a large polyp. The following is an example from a more recent case:  I was able to see this polyp in the regular straight view, but due to the location of the polyp on a fold, I could not see the entire thing. The first thing I tried was injecting some saline behind the polyp to try and lift it forward towards the scope. Well, the lesion lifted well, but still was really hard to see and proved impossible to get the snare around. Retroflexing in the ascending colon solved that problem easily:

Retroflexed view in the ascending colon: Red arrow shows a polyp behind a fold. The lesion was injected with saline (prior to taking this picture), and then removed with a hot snare.
Retroflexed view in the ascending colon: Red arrow shows a polyp behind a fold. The lesion was injected with saline (prior to taking this picture), and then removed with a hot snare.

You may also have to retroflex to treat bleeding, such as a bleeding angiodysplasia, or a bleeding polypectomy site. Sometimes a polyp that was easy to see is removed and the site retracts behind a fold and becomes almost impossible to see. If that site bleeds a few days later, retroflexion to get in a better position to place clips straight onto the site may be the best way to treat it.

Should retroflexion in the right colon become a routine part of screening colonoscopy? Let’s frame this question with the following facts: Colonoscopy is less-protective against right-sided cancers (which implies that colonoscopy is less-effective at finding or removing right-sided polyps.) Polyp detection in the right colon is more difficult for several reasons (flat lesions, prep quality). Another one of these reasons is that polyps may easily hide behind folds and be impossible to see in forward-view.

To combat the risk of right-sided colon cancers, some authors have advocated a routine second-examination of the right colon during screening colonoscopy. A routine second-exam from the hepatic flexure to the cecum (in regular forward view) has been shown to yield an additional adenoma about 10% of the time. To me, this is a big deal, and means that by not looking twice at the proximal colon, we are missing small polyps in 1 out of 10 patients. As it turns out, there is a statistically similar increase in polyp detection if the second exam is done in retroflexed view.

The take home message is that performing a second proximal colon exam is important, either in forward view, or retroflexed view. Doing it retroflexed has the theoretical benefit of allowing you to see things from a different angle and possibly pick up lesions that would be missed by repeat forward view. The studies don’t really support that a retroflexed view is any better than a repeat forward view, however the important thing is that you do a second look at all.

The following reference is an excellent practical read on the topic, and is free to download on the AJG website:

Rex DK. How I approach retroflexion and prevention of right-sided colon cancer following colonoscopy. Am J Gastroenterol 2016;111:9-11.

Additional reference:

Kushnir VM, Oh YS, Hollander T, et al. Impact of retroflexion vs. second forward view examination of the right colon on adenoma detection: a comparison study. Am J Gastroenterol 2015;110:415-22.

Since the name of my site is Retroflexions, it’s about time I wrote an article about how to retroflex! More specifically, how does one retroflex in the right colon? (Fair warning: This article is probably only interesting to gastroenterologists.)

Retroflexed scope in the ascending colon.
Retroflexed scope in the ascending colon.

Let’s cover the how part first…and keep in mind it’s actually really simple to do in the right setting. Starting in the proximal ascending colon or cecum:

Step 1: Turn the big wheel all the way up.

Step 2: Turn the little wheel all the way left.

Step 3: Gently and slowly torque the insertion tube counter-clockwise until you feel or see the scope retroflex. Unlike the rectum, you usually don’t need to push scope into the patient to retroflex in the right colon.

Once the tip is turned back on itself, you can gently maneuver the scope to get a better view. This might require inserting the scope a little to get the tip away from the mucosa, or further rotating the insertion tube.

This is a very safe maneuver if done in the right patient. The favorable situation is a straight scope without any loops in the sigmoid colon, a decently large diameter ascending colon, and an otherwise healthy colon (e.g., don’t retroflex in a patient with active colitis, etc.). If the maneuver is not happening easily for whatever reason, or you feel resistance, just stop!

I should also mention how to get out of the retroflexed view and back into the regular forward view: Release the wheels and allow them to return to neutral, then slowly withdraw the scope and allow the retroflexed tip to straighten…it’s easy!

Like any technique, it is a good idea to “practice” this often when the optimal situation presents itself (straight scope in a straight, clean, healthy colon). You never know when you might need this skill to remove a polyp or treat a bleeding site that is otherwise impossible to get to in forward view, and you don’t want to fiddle around with it for the first time in a situation where you really need it to work.

As with most things, knowing how is the easy part. Next time we will cover the more important question of why one would want to retroflex in the right colon. Stay tuned…

[Go to part two of the series]



This post has nothing to do with being a doctor specifically. Everybody can benefit from some introspection regarding what they do every day to make themselves better at…well, whatever it is they do! At the risk of sounding like a self-help post, here it goes:

Are you constantly trying to refine yourself into a better version of you, or are you simply getting up and doing the same thing every day, hoping for different results from the day prior? When a situation turns our poorly, do you think about why it happened, or do you chalk it up to bad luck and/or blame it on other people? When you don’t know why something happened, do you go searching for the answers? Chances are other people have had the same issues…do you try to see if others have already solved your problem before reinventing the wheel?

Do you ever step back and look at yourself?
Do you ever step back and look at yourself?

Experience is an invaluable teacher, and often those with more experience are just better at doing whatever it is they do. However, we must be careful to make sure our experience is mindful and not just based on the amount of time we do something: High-quality experience necessitates both time and constant correction in process.

This whole tangent of a post comes from a story from my fellowship. To get right to the point, there were certain supervising attendings that were great role models–they were comfortable teaching and communicated clearly, they were confident in what they knew, and more importantly they knew when it was time to look something up. Then there were some attending that were the complete opposite: Uncomfortable in a teaching position (probably due to a lack of confidence and knowledge), they would try to mask their flaws by citing their authority granted by “many years of experience” in the field. These were the attendings that would seem really smart when you first started fellowship, but that would soon be eclipsed in knowledge by some of the better fellows only a few years later.

I once asked a teaching attending why they do a certain thing a certain way (since it was different from the way we were taught by everyone else) and was told “because in my twenty years of experience, that’s the way I’ve always done it!” It just so happens that this interaction occurred during a particularly low point of my fellowship, and I blurted out “Do you have twenty years of experience, or one year of experience repeated twenty times?”

Needless to say, after a brief meeting with the program director where fancy words like “insubordination” were thrown around, I made a brief (and required) apology to the attending doctor. I did learn a valuable lesson that day, but it had nothing to do with my reprimanding: When someone cites their “years of experience” as equivalent to actual data derived from high-quality studies, they have just lost the argument and have nothing more to say. It’s like a parent saying “because I said so!” as an explanation for something to their grown child that has already gotten married and moved out of the house.

Don’t let your ego get in the way of learning from your mistakes. Mindful experience means that you’re constantly looking for ways to do things better. I’d rather be under the care of the doctor with five years of experience who is continuously honing his thought process and is growing better every day, then the doctor with twenty years of “experience” who is just robotically putting in the time until the day is over. Of course it would then stand to reason that the doctor with twenty years of high-quality mindful experience is probably the best of them all…would you agree?

Image via Herbut

After removing a large polyp endoscopically, it is recommended to follow up the site about 3-6 months later to make sure the entire lesion was removed and prove there is no further adenomatous tissue to resect. Often there is still a small amount of remaining tissue at the site, either from the edges of the polyp, or from tiny “islands” of adenomatous tissue from the base of the lesion, in between the snare polypectomy sites. Either way, residual adenomatous tissue is usually easy to deal with on the follow-up colonoscopy, and can be removed just like any other polyp.

Sometimes there is a little bit of abnormal-appearing tissue at the polypectomy scar that is not adenomatous. Rather this is granulation tissue (scar tissue) that results from the healing process, and is non-neoplastic. This can often be determined visually, but should also be biopsied to confirm that it is a benign process and not missed polyp tissue.

The following picture shows a large polyp that was removed endoscopically. You might remember the picture from this article. This patient was then rescoped 6 months later to re-examine the site:

After spraying the lesion with methylene blue dye, the edges of the polyp are more apparent (red arrows show the edges of the lesion).
The original polyp, prior to removal. Red arrows show the edges of the lesion.


The site 6 months later. Red arrow shows the small piece of granulation tissue present at the scar site.
The site 6 months later. Red arrow shows the small piece of granulation tissue present at the scar site.

As you may have noticed, there is a tiny “nubbin” of tissue found at the center of the otherwise clean polypectomy scar. This was removed with biopsy forceps and turned out to be benign granulation tissue, indicating that the initial resection was complete. This is not always the case however, and as many as 31% of these large polyp sites can have residual polyp detected on follow-up colonoscopy, so make sure to do that colonoscopy in 3-6 months to check!


Knabe M, Pohl J, Gerges C, et al. Standardized long-term follow-up after endoscopic resection of large, nonpedunculated colorectal lesions: a prospective two-center study. Am J Gastroenterol 2014;109:183-9.

I’d like to share this interesting case to highlight a few techniques for removing large polyps endoscopically. This patient was found to have a large polyp several months ago at an outside facility, with an unclear plan for follow up. He presented with an unrelated issue to one of our hospitals, and was found to be anemic and had guaiac positive stool. On colonoscopy, this large polyp was found in the ascending colon:

Granular-type lateral spreading tumor (red arrows show edges of lesion)
Granular-type lateral spreading tumor (red arrows show edges of lesion)

The fancy term for this large polyp is “granular-type lateral spreading tumor.” It is my opinion that most things containing the word “tumor” should be removed from the human body when possible. So how are we going to do it?

As you probably guessed, endoscopic mucosal resection is the simplest and safest way to remove a big polyp like this one. As always, we carefully inspect the borders of the lesion, and also look at the lesion itself to see if there are any signs of advanced cancer that would preclude endoscopic resection. Then we start with submucosal injection of a large volume of fluid to lift the lesion (in this case I used saline with methylene blue).

After lifting the distal edge of the lesion
After lifting the distal edge of the lesion

Starting at the distal edge of the lesion (the part closest to the tip of the scope), injection and resection with a stiff snare is performed repeatedly in a piecemeal fashion until most of the polyp is removed. What was difficult about this lesion was not really the size, but the fact that the proximal-most part of the polyp (about 15% of the entire lesion) was difficult to lift and became impossible to capture using various snares in the forward-viewing position. The snare would just slide off, no matter how well I thought I had grabbed the lesion.

Sometimes repositioning the lesion is what it takes to get it done. A better angle between the snare and the polyp can be the difference between sliding over the top or capturing the lesion. In this case, retroflexing the scope in the ascending colon was the key maneuver needed to get the rest of the polyp out.

Retroflexed view of the polyp base: (L) Blue arrow shows the colonoscope; (R) Red arrows show the remaining polyp tissue.
Retroflexed view of the polyp base: (L) Blue arrow shows the colonoscope; (R) Red arrows show the remaining polyp tissue.

Now that the remaining polyp can be approached at a better angle, it is reinjected and then removed with the snare. Some of the edges are then “touched up” with hot biopsy avulsion. While still retroflexed, a few clips are placed to approximate the edges of the part we just resected, as this is the deepest part of the resection.

After resection: (L) Polyp base; (R) After 3 clips applied in retroflexion. A total of 8 clips were used to close this defect.
After resection: (L) Polyp base; (R) After 3 clips applied in retroflexion. A total of 8 clips were used to close this defect.

Finally, after placing a tattoo, the pieces of polyp that we just took off are collected for pathology, and we are done!

So in summary, here are a few tips when removing large polyps like this one:

  • Be prepared-have all equipment ready to go and within arm’s reach of your staff.
  • Be patient-this might take a while. It’s better to do it right the first time!
  • Be flexible-use different techniques (like retroflexion) as dictated by the demands of the situation.


Pathology revealed a tubulovilous adenoma with a focus of intramucosal adenocarcinoma. This patient will need a follow up colonoscopy in 3 months to assess the site.