In this episode of PodMD, Gastroenterologist Dr Matt Kitson will be discussing the topic of interpreting colonoscopy reports and histology. We discuss what to look for in these reports and their importance, how to manage patients with multiple risk factors, stratifying patients into categories of risk, when to seek clarification from endoscopists, and delivering follow-up care.
- Transcript
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Today I’d like to welcome back to the PodMD studio Dr Matt Kitson.
Dr Matt Kitson is an experienced Gastroenterologist and Hepatologist providing care in the Eastern and Southeastern suburbs of Melbourne, and also in Gippsland.
You can read more about Matt on his profile page on our PodMD website.
*Please listen to our disclosure at the end of this podcast
The topic of today’s discussion is a guide to interpreting colonoscopy reports and histology. Matt, great to have you back on PodMD!
Matt: Thanks for having me back again. It’s always a pleasure to be on this podcast.
To begin, can you explain what GPs look for when first evaluating a patient’s colonoscopy and histology report?
Matt: Yeah, so the colonoscopy and subsequent histology reports are something that frequently comes across a GP’s desk, and I really wanted to help give some guidance on how to interpret them and certain things to look out for in these reports.
Firstly, with the colonoscopy report, it’s important to know what the extent of the colonoscopy is, and ideally the terminal ileum should be intubated in most patients and photo documentation of the cecum or ileum should be embedded into every report as well.
The other thing to look out for is the quality of the bowel prep, and ideally this should be good or excellent. The withdrawal time, which is the time taken from the colonoscope reaching the cecum to the end of the colonoscopy, should be documented at the bottom of the report as well as is a marker of quality. Also, the number of polyps that were identified and removed, and the location of these polyps and the size of the largest of these polyps is important.
And the final thing to look out for is whether hot snare polypectomy or cold snare polypectomy was used to resect any polyps. Ideally, cold snare should really be the default method, and we reserve hot snare polypectomy for larger polyps, or potentially pedunculated polyps. As with hot snare polypectomy, there’s a higher risk of delayed post polypectomy bleeding.
Why is it important for GPs to review both the colonoscopy and histology reports rather than relying on one alone?
Matt: That’s a very good question. So generally, at colonoscopy, the proceduralist has an idea of the type of polyp that is removed – but occasionally we do see unexpected results on histology, or there can be discordance between the colonoscopy findings and what’s seen under the microscope on histology – so merging the two together is really important.
Some of the things that we occasionally see that can be potentially expected or unexpected is the presence of malignancy in a polyp that’s been removed, or high-grade dysplasia in an adenomatous polyp, so that’s essentially one step away from becoming a malignancy.
The other thing to keep an eye out for on a histology report is the presence of any dysplasia, whether low or high grade in a sessile ulcerated lesion, which are these sometimes-difficult-to-identify lesions in the right colon. And the other thing that can sometimes commonly be seen on random colonic biopsies which are taken to evaluate for diarrhea is the presence of lymphocytic or collagenous colitis.
The final thing I’d like to say about where histology is very, very helpful is that if the histology confirms that a rectosigmoid polyp that is removed is a hyperplastic polyp, then this is quite reassuring. And generally, if these are the only types of polyps that have been removed, they don’t require a follow-up surveillance colonoscopy if they’re present in the rectum or the sigmoid colon and they’re less than 10 millimeters in size. So, merging both the colonoscopy report and the histology report to get a full picture is very, very helpful.
And what findings in these reports help stratify patients into low, moderate and high-risk categories?
Matt: Okay, so this is going to be a fairly long answer. So, I’ll start with what puts a patient into a high-risk category. So, any larger polyps are generally 15 to 20 millimeters in size or more that requires a piecemeal resection, either with cold snare polypectomy or hot snare polypectomy. In these large polyps remove piece root meal, there’s a significant risk of polyp recurrence. The presence of high-grade dysplasia in an adenomatous polyp is also a high-risk feature as it’s one step away from cancer, and identifying the reception margin, so how far away that focus of high-grade dysplasia is from where the polyp is also very important. Again, I mentioned the presence of any dysplasia in a cesulcerated lesion is a high-risk feature as once cesulcerated lesions develop dysplasia, they can progress very rapidly to adenocarcinoma. The presence of 10 or more adenomatous polyps a patient with Lynch syndrome or serrated polyposis, or a patient with ulcerative colitis with concomitant primary sclerosing cholangitis, these are again all very high-risk features. These patients with these high-risk category may require a repeat colonoscopy anywhere between three and 12 months.
The next category is patients at moderate risk. So, these patients who have advanced adenomatous polyps where the largest polyp is 10 millimeters or more in size, or if there are villous features in a polyp, so it’s a villous adenoma or a tubular villous adenoma, these are all advanced adenomas. If five to nine adenomatous polyps removed in any given colonoscopy or three or more cesulcerated lesions or a cesulcerated lesion 10 or more millimeters in size, this is all puts a patient in a moderate risk category as well as a much rarer polyp called a traditional serrated anoma if that’s been removed. So these patients in a moderate risk category often require a repeat colonoscopy in three years’ time.
And I’ll finish off with the low-risk category, which is the majority of patients. So, these are the patients with the standard sort of family history of colorectal cancer in one or more first degree relatives under the age of 60, if one to four adenomatous polyps less than 10 millimeters in size are removed with only low-grade dysplasia, or if one to two cesulcerated lesions less than 10 millimeters in size and no dysplasia are removed. And these most common category of low-risk patients often require a repeat colonoscopy in five years’ time.
How should GPs manage patients who have multiple risk factors, such as family history, poor prep, potential incomplete polyperception, when determining follow-up timing?
Matt: So, often patients who have poor bowel prep or a kind of borderline adequate bowel prep, or if there’s the potential incomplete resection due to a larger polyp being removed piecemeal, these patients will often have a repeat colonoscopy sometime within the next 12 months. If the patient’s had poor prep, often they will have a repeat procedure either with an extra sachet of bowel prep or they might be placed on Movicol for a week beforehand.
And the risk factors for poor bowel prep are things like diabetes. If a patient’s had a history of previous poor bowel prep or if moderate to severe diverticulosis is present on previous colonoscopies, as well as medications such as Opiates as well, they’re all significant risk factors for poor bowel prep. In general, family history is usually less of a concern in putting a patient into a high-risk category unless there’s a specific genetic mutation associated with this family history or if the family history is that of Lynch syndrome.
And can you explain the rationale behind specific colonoscopy follow-up intervals?
Matt: So, the timing of the repeat surveillance procedure is based on the patient’s risk stratification, which I went through in that previous question, and there’s actually specific Medicare item numbers for the colonoscopy based on what their risk category is of low, moderate or high. And as I mentioned, the majority of patients will be at low risk and in general, a repeat procedure in five years is satisfactory.
But, as mentioned previously, some patients will be at moderate risk if they have an advanced adenomatous polyp. So those adenomatous polyps, 10 millimetres or more incisal with villous features, they have five or more adenomatous polyps present or three or more cesulcerated lesions present or a cesulcerated lesion greater than 10 millimetres in size.
And then the few patients that are in the high-risk categories are the ones with the larger polyps removed piecemeal. The presence of high-grade dysplasia in an adenomatous polyp, any dysplasia in a cesulcerated lesion 10 or more adenosine polyps. These are the patients that will often get back somewhere between three and 12 months.
And I just want to finish off again finally with rectosigmoid hyperplastic polyps. If these are 10 millimetres in size, then generally these patients don’t require follow-up surveillance colonoscopy as this doesn’t convey any higher risk of colorectal cancer.
In what situations should a GP seek clarification from the endoscopist before scheduling their patient’s next colonoscopy? And why is this step important for ensuring appropriate follow-up care?
Matt: Yes, that’s a very good question. So, the main takeaway from this is that I think if you have any worries, concerns, or questions about the timing or necessity of a surveillance procedure, then send the patient back to see the proceduralist to clarify what is the appropriate follow up plan, is a perfectly reasonable thing to do. And certainly, I would be very happy to see a patient in this scenario where there’s questions about follow up.
What should a GP look for on a colonoscopy report to reassure them that the patient has had a high-quality colonoscopy?
Matt: So, I’ve kind of flagged this previously, but I’ll go through it again because it is really important. So, photo documentation of either cecal or ileal intubation and preferably ileal intubation, as this can be certain pathology seen in the terminal ileum occasionally at colonoscopy. Whether the quality of the bowel prep has been documented and ideally, the quality of this bowel prep should be rated as either good or excellent so that we have a much better chance of identifying and removing polyps.
The withdrawal time should be documented, and this should really be at least 6 minutes between the colonoscope reaching the cecum and the end of the procedure. The importance of the withdrawal time is because a slower withdrawal time is associated with a higher adenoma detection rate and a higher sessile ulcerated lesion detection rate. And this conveys a lower risk of one of the things that we really worry about, which is called post colonoscopy colorectal cancer. So, with withdrawal time in colonoscopy, slower is better.
The other thing I’d like to mention that GPs might not be aware of, is that often artificial intelligence is now used to augment polyp detection during colonoscopy with a lot of the newer scopes and stats that we have. And this is rapidly becoming the standard of care in colonoscopy. However, the use of AI during a procedure isn’t currently routinely documented in a colonoscopy report, but that may well change down the track.
What should a GP do when a patient has persistent symptoms despite a normal colonoscopy?
Matt: In this scenario, I think that the best management plan is that if you have any concerns or the patient has any concerns, then get them to see the procedurals for follow-up. Often patients with a functional gut disorder, which can be present in up to 10 to 15% of the population will have a normal colonoscopy, and they will also have ongoing symptoms. But it’s important to be aware that colonoscopy is not 100% accurate in diagnosing colorectal cancer, and 5 to 8% of all bowel cancer diagnoses in Australia is a post colonoscopy colorectal cancer. So, this is a bowel cancer that was diagnosed where the patient has had a colonoscopy recently and the follow-up colonoscopy that the cancer was diagnosed at was actually before, when the next colonoscopy was planned. So it’s just important to be aware of that.
Yep… what information in the colonoscopy report is most critical for GPs to act on immediately, and what can safely wait for histology?
Matt: So in general, the obligations are on the proceduralist to follow these important and urgent things up. So GPs don’t need to worry too much about this. So specifically, when a malignancy is diagnosed at colonoscopy, it’s generally obvious at the time and the proceduralist is obliged to arrange the appropriate staging and follow up management. The other thing to be aware of that sometimes we diagnose quite severe ulcerative colitis at colonoscopy. This can actually be so severe that a patient might require admission, but it’s really the responsibility of the proceduralist to arrange appropriate management and follow up as well.
And how do these reports help GPs tailor lifestyle advice, screening reminders and symptom monitoring?
Matt: So some specific scenarios that can be very helpful in managing symptoms are if diverticulosis is present at the colonoscopy and this is causing symptoms such as constipation or diarrhea or left iliac loss or discomfort, then I often find that fibre supplementation will help significantly improve these symptoms. So, if you see a patient with moderate to severe diverticulosis, then fibre will often help improve these symptoms. The next point that I would make, that if an adenomatous polyp or a cesosterated lesion is removed at colonoscopy and it’s determined that a surveillance colonoscopy is appropriate for that patient, then further bowel cancer screening with faecal occult blood testing is unnecessary. So these patients don’t need to be doing another FOBT two or three years afterwards if they’re due to have a follock colonoscopy. The final thing I’d mention is it is actually quite helpful if the follow up reminder for the colonoscopy at the appropriate surveillance interval is placed in the GP practice software so that there’s a backup mechanism to remind the patient about the timing of when the next colonoscopy is due.
Yeah, perfect. And to sum up for us, could you please identify the three key take home messages from today’s podcast?
Matt: So the first point I’d like to reiterate is that high-quality colonoscopies are safe and it’s effective at decreasing the risk to a patient of colorectal cancer; but it’s important to be aware of features on a colonoscopy report that indicate that the patient’s received a high-quality colonoscopy – so that’s photo documentation of ileal cecal intubation, documentation of either good or excellent bowel prep, and documentation of a withdrawal time greater than six minutes.
The second point I’d like to reiterate is it’s important to be aware of the rationale behind the timing of the follow-up surveillance colonoscopy. So, in general, five years for low-risk patients, which will be the majority of patients, three years for moderate-risk patients, which will be a significant minority of patients, and three to twelve months for high-risk patients who will be overall small proportion. Over servicing a colonoscopy in Australia is a significant problem and it’s something that Medicare is actively trying to manage and decrease the incidence of, as it’s not a procedure entirely without risk and it also comes with a significant cost of the procedure to the taxpayer as well.
And the final point I’d like to reiterate is that histology is really an important part of the colonoscopy and the report, as occasionally there is discordance in the findings of colonoscopy or there can be really unexpected findings that will alter the follow-up management of the patient.
That’s great. Thank you, Matt. And thanks very much again for your time and insights today.
Matt: Thank you.
