Initial Colonoscopy Research Articles

Analysis of risk factors for post-polypectomy bleeding and polyp recurrence after colonoscopic polypectomy in children

Objective: To explore the incidence and the risk factors of post-polypectomy bleeding and polyp recurrence after colonoscopic high-frequency electrocoagulation snare polypectomy. Methods: Clinical data of 1 826 children who underwent colonoscopic high-frequency electrocoagulation snare polypectomy in the Children's Hospital, Zhejiang University School of Medicine from January 2009 to December 2020 was retrospectively analyzed. Demographic characteristics, endoscopic manifestations, pathological features, diagnosis, occurrence of post-polypectomy bleeding and polyp recurrence were collected. The associated risk factors were analyzed by Logistic regression. Results: A total of 1 826 children (1 191 males and 635 females) with 1 967 polypectomies were included. The age was 4.6 (3.2, 6.4) years at initial diagnosis. According to the initial colonoscopy, 1 611 children (88.2%) had solitary polyps, 1 707 children (93.5%) had pedicled polyps, 1 151 children (63.0%) had polyps involving the rectum, and 1 757 children (96.2%) had hamartomatous polyps. Polyposis syndromes were diagnosed in 73 children (4.0%). The post-polypectomy bleeding occurrence was 3.8% (75/1 967). Polyps recurred in 88 children (4.8%). Girls (OR=2.01, 95%CI 1.26-3.23) and sessile polyps (OR=2.28, 95%CI 1.15-4.49) were risk factors for post-polypectomy bleeding (both P<0.05). Multiple polyps (OR=17.49, 95%CI 9.82-31.18), right-colon involvement (OR=3.44, 95%CI 1.89-6.26) and non-hamartoma (OR=2.51, 95%CI 1.04-6.07) were risk factors for polyp recurrence (all P<0.05). Conclusions: Colonoscopic high-frequency electrocoagulation snare polypectomy has low incidence of post-polypectomy bleeding and polyp recurrence. Female patients and sessile polyps have higher risk for post-polypectomy bleeding. Multiple polyps, right-colon involvement and non-hamartoma polyps increase the risk for polyp recurrence.

A single centre audit: repeat pre-operative colonoscopy.

Repeat colonoscopy may be required for tumour localisation. The aim of the study is to explore the clinical settings it was used and benchmark the quality of initial colonoscopy against standardized guidelines for tumour localisation, tattooing and colonoscopy reporting amongst clinicians. A retrospective study from 2016 to 2021 has been performed on patients who underwent elective colorectal cancer resections at the Northern Hospital. Patient demographics, colonoscopic and operative details were retrieved from the Bi-National Colorectal Cancer Audit (BCCA) Registry database and hospital medical records. changes in operative approach and delays to operation. reasons for a repeat colonoscopy and complications from repeat colonoscopy. A total of 339 patients were included in this study. 94 (28.6%) underwent a repeat colonoscopy. Re-scoping rate was 29.6% for surgeons, and 26.2% for non-operating endoscopists. Surgeons had a 5.9% localisation error rate, and non-operating endoscopist 6.95% (p= 0.673). Surgeons did not have a lower rate of repeat colonoscopy (p= 0.462). Repeat endoscopy was associated with a longer time to definitive operation (p < 0.001). No complications were associated with a repeat colonoscopy. There was no difference in localisation error rates or repeat colonoscopy amongst surgeons (29.6%) and non-operating endoscopists (26.2%) (p= 0.462). This could be explained by the standardized endoscopy training in Australia governed by a common training board. Lack of tattooing at index colonoscopy and inadequate documentation often led to a repeat endoscopy, which was associated with a longer time to definitive operation. Standardized guidelines in tattooing of lesions and colonoscopy reporting should be implemented.

Atezolizumab‐associated colitis mimic inflammatory bowel disease: A case report

AbstractImmune checkpoint inhibitors (ICIs) are monoclonal antibodies that target downregulators of the anticancer immune response. ICIs have revolutionized the treatment of various malignancies. However, many immune‐related adverse events have also been described, which mainly occurs when the immune system becomes less suppressed, and affects various organs, including the gastrointestinal tract. We report a case of atezolizumab‐associated colitis with clinical and endoscopic follow‐ups. The patient was a 72‐year‐old male diagnosed with advanced squamous cell lung cancer treated with atezolizumab and combination chemotherapy. Two months after atezolizumab therapy, bloody diarrhea and abdominal pain were reported. Initial colonoscopy revealed colonic ulcers with diffuse erythema and loss of vascularity. Histology demonstrated ulcerated mucosa with acute inflammation. Steroids were promptly indicated due to suspicion of immune‐related colitis caused by atezolizumab. Follow‐up sigmoidoscopy performed 6 weeks after initiating steroid therapy showed improvement of inflammation. Histological findings revealed eroded colonic mucosa with abortive crypts, lymphoplasma, and eosinophil cell infiltration, which mimicked inflammatory bowel disease (IBD). However, there was no colitis relapse after steroid discontinuation. The case demonstrated endoscopic and histological presentations of immune‐mediated colitis that mimicked IBD.

Comparison in the development of colorectal cancer after screening colonoscopy between elderly and younger population.

This study aimed to evaluate and compare the incidence of colorectal cancer (CRC) in elderly participants aged ≥75 years and those <75 years who had previously undergone a colonoscopy. This retrospective cohort study was conducted at the Center for Preventive Medicine at St. Luke's International Hospital in Japan. All participants who underwent screening colonoscopy between 2005 and 2015 were included and followed up until 2020. Our primary outcome was the identification of CRC as confirmed by pathology after screening colonoscopy. We compared the development of CRC between the two groups using survival analyses. A sub-analysis to evaluate the incidence of CRC among participants with and without neoplastic polyp resection at initial colonoscopy was also performed. A total of 8350 participants were enrolled; the median follow-up period was 2982 days (interquartile range:1932-4141), mean age was 52.5 years (SD: 11.5) and 5274 (61.3%) participants were men. The incidence of CRC during the follow-up period was 82 (0.95%) among all participants and 11 (4.31%) among the elderly participants. Elderly participants showed a significantly higher incidence of CRC than the other group [hazard ratio, 2.56; 95% confidence interval (CI), 1.14-5.75]. The sub-analysis showed that out of 2878 participants with a neoplastic polyp at the initial colonoscopy, 52 (1.81%) developed CRC (hazard ratio, 2.85; 95% CI, 1.16-6.98). A repeat colonoscopy might be warranted in people with high activities of daily living and few comorbidities, especially if there is a history of neoplastic polypectomy at the first colonoscopy.

P180 The prevalence and clinical course of atypical distribution of inflammation in newly diagnosed ulcerative colitis

Abstract Background Ulcerative colitis (UC) is characterized by continuous mucosal inflammation extending from rectum to the proximal lesion. However, there are cases of atypical distribution of inflammation, such as appendiceal orifice inflammation (AOI), skipped lesion, and rectal sparing. This study aimed to evaluate the prevalence and clinical course of atypical distribution of inflammation in newly diagnosed UC. Methods Between 2013 and 2021, 374 patients who underwent a colonoscopy at the time of diagnosis of UC were retrospectively reviewed. Clinical courses including relapse rate within 1-year, 2-year of diagnosis and exposure to immunomodulator or biologics during follow-up were retracted from the prospective IBD registry (ClinicalTrial.gov, NCT02193464). Atypical UC was defined as patients with AOI, skipped lesion or rectal sparing at initial colonoscopy. The clinical courses and changes of endoscopic findings were compared between typical UC group and atypical UC group. Results Of 374 patients, 116 (31.0%) categorized as atypical UC; specifically, 90 (24.1%) showed AOI, 17 (4.5%) showed rectal sparing and 49 (13.1%) showed skipped lesion. When 90 patients with AOI were reclassified according to the extent of inflammation, 62(16.6%) had a localized inflammation at peri-appendiceal area, 13(3.5%) had an inflammation of the entire cecum, 15(4.0%) had an inflammation extends to the proximal A-colon. The clinical courses of atypical UC were not different from typical UC group, however, patients with skipped lesion showed a lower 1-year relapse rate compared to those without skipped lesion (P=0.042). Of 96 patients with atypical UC who underwent follow-up endoscopy, 73 (75.8%) demonstrated a typical distribution of UC at their follow-up colonoscopy. Conclusion Atypical distribution of UC including AOI, skipped lesion, and rectal sparing are not uncommon in patient with newly diagnosed UC. However, most of these features do not appear to correlate significantly with prognosis in the clinical course of UC. In majority of patients with atypical UC, the lesion turned into typical UC on follow-up colonoscopy.

Is urgent colonoscopy without bowel preparation really usefulness? Colonoscopy without bowel preparation

Acute lower gastrointestinal bleeding (LGIB) is a common disorder which involves many problems in diagnosis and treatment. Concerning colonoscopy in an urgent context, guidelines are very specific in stating that unprepared colonoscopy has no place in the evaluation of patients with suspected LGIB. The purpose of this study was to evaluate the diagnosis and therapeutic effectiveness of urgent colonoscopy, without prior bowel preparation, in patients admitted at the hospital with acute LGIB. Were included 132 patients consecutively admitted at the Emergency Department for LGIB and who had undergone colonoscopy without prior bowel preparation. Despite the lack of preparation, cecal observation was possible in 10 patients (7.6%). More than two thirds of the diagnoses (69.1%) were established with the performance of just a left colonoscopy. In 63.6% of patients, a definitive diagnosis was established using this initial approach. In 35.6% of the individuals, biopsies were performed, which allowed the establishment of a histological diagnosis. Additionally, in 14 patients (16.7%) an active hemorrhagic focus was identified, and endoscopic hemostasis was performed. None of these 14 patients required additional procedures during the hospital stay. Only in 21 patients the initial colonoscopy was inconclusive and, consequently, it was necessary to repeat it after anterograde preparation. Even in these cases, no diagnosis was reached in 33.3%. This study revealed that unprepared colonoscopy in an urgent context could a useful procedure which allows an adequate guidance in more than half of the patients.

Primary CT Angiography Vs Colonoscopy in Acute Lower Gastrointestinal Hemorrhage

Background and AimsAcute lower gastrointestinal bleeding (LGIB) is a common cause of hospitalization and results in significant morbidity and cost. Advancements in computed tomography with angiography (CTA) imaging capability brings into question whether its use as a primary intervention for undifferentiated LGIB in place of colonoscopy could result in improved outcomes. MethodsRetrospective cohort analysis of admitted patients >18 years old who presented between January 2010 and August 2018 with an initial episode of LGIB who underwent colonoscopy or CTA as primary diagnostic intervention. Chi-square or Fisher's exact were used to compare primary outcomes of bleeding detection and intervention rates, t-test for length of stay (LOS) between CTA and colonoscopy. Logistic regression models were built to compare source identification and hemostatic intervention rate. ResultsOf 258 total patients, 162 underwent initial colonoscopy vs 96 CTAs. When controlling for hypotension, anticoagulation, transfusions, and time to intervention, colonoscopy was associated with decreased LOS (5.00 vs 6.9, P = 0.001), a higher probability of source identification (OR 3.64, P < 0.001, CL 1.92-6.90) and hemostatic intervention (OR 8.62, P < 0.001, CI 3.54-21.0) compared to CTA. In a subgroup analysis of diverticular bleeds, CTA had higher rates of therapeutic intervention compared to colonoscopy (18% vs 3.8%, P < 0.001, OR 0.09, CI 0.02-0.46) without mortality benefit or shorter LOS. ConclusionIn patients with undifferentiated LGIB, colonoscopy as the primary modality for evaluation results in higher source identification, hemostatic intervention, and shorter LOS. In diverticular bleeds, early CTA was associated with increased hemostatic intervention rate.

Endoscopic management of delayed bleeding after polypectomy of small colorectal polyps: two or more clips may be safe.

BackgroundThe resection of small colorectal polyps (≤10 mm) is routine for endoscopists. However, the management of one of its main complications, namely delayed (within 14 days) postpolypectomy bleeding (DPPB), has not been clearly demonstrated. We aimed to assess the role of coloscopy in the management of DPPB from small colorectal polyps and identify the associated factors for initial hemostatic success.MethodsWe conducted a retrospective study of 69 patients who developed DPPB after the removal of colorectal polyps of ≤10 mm and underwent hemostatic colonoscopy at the Sixth Affiliated Hospital of Sun Yat-sen University (Guangzhou, China) between April 2013 and June 2021. Demographics, clinical variables, and colonoscopic features were collected independently. We applied univariate and multivariate analyses to assess factors associated with initial hemostatic success.ResultsGeneral colonoscopy without oral bowel preparation was successfully performed in all the patients, with a median duration of 23.9 (12.5–37.9) minutes. Among 69 patients, 62 (89.9%) achieved hemostasis after initial hemostatic colonoscopy and 7 (10.1%) rebled 2.7 ± 1.1 days after initial colonoscopic hemostasis and had rebleeding successfully controlled by one additional colonoscopy. No colonoscopy-related adverse events occurred. Multivariate analysis showed that management with at least two clips was the only independent prognostic factor for initial hemostatic success (odds ratio, 0.17; 95% confidence interval, 0.03–0.91; P = 0.04). All the patients who had at least two clips placed at the initial hemostatic colonoscopy required no further hemostatic intervention.ConclusionsColonoscopy is a safe, effective, and not too time-consuming approach for the management of patients with DPPB of small colorectal polyps and management with the placement of at least two hemoclips may be beneficial.

Risk for Colorectal Cancer in Patients with Serially Positive Fecal Immunochemistry Test in an Annual Screening Program.

Objectives: There are patients who do not undergo colonoscopy even if the fecal immunochemistry test (FIT) results are positive and even with repeated positive test results the following year. We aimed to investigate colorectal cancer (CRC) risk in examinees with positive FIT results in our annual screening program. Methods: We analyzed patients who underwent initial colonoscopy from April 2010 to March 2017 because of positive FIT results using an endoscopy database in our hospital. We investigated the difference in the risk of advanced colorectal neoplasia as a surrogate marker of CRC between those who had an initial positive test and those who had repeated positive tests. Results: A total of 748 patients were included in this analysis. The advanced neoplasia detection rates were 7.6% (50/656) and 18.5% (17/92) for the initial and repeated positive test groups, respectively. Subgroup analysis of those with repeated positive tests revealed that the detection rates in examinees with positive tests 1-2 and >2 years ago were 16.7% (6/36) and 19.6% (11/56), respectively. The odds ratios for advanced neoplasia detection in patients with positive tests 1-2 and >2 years ago compared with those in the initial positive test group were 2.72 (95% confidence interval [CI], 1.04-7.10) and 3.09 (95% CI, 1.47-6.48), respectively. Conclusions: The risk of CRC appears more than doubled in patients with a repeated positive FIT result. Prompt colonoscopy is recommended for FIT-positive cases.

S1715 A Case of Collagenous Colitis Masquerading as Crohn’s Disease

Introduction: Collagenous colitis (CC) is a subtype of microscopic colitis characterized by chronic large volume watery diarrhea, few or no endoscopic abnormalities, and histopathology showing irregular subepithelial collagenous band-like deposits and epithelial lymphocytic infiltration. Colonic ulceration in CC is rare, with frequency between 1.9-3.0%. We present a patient with diffuse colonic ulceration on endoscopy, but with biopsy findings and response to treatment consistent with CC. Case Description/Methods: A 34-year-old woman with psoriatic arthritis, uveitis, and Grave’s disease was referred for colonoscopy for chronic diarrhea evaluation. She reported a one-year history of 7-10 watery, non-bloody bowel movements per day associated with abdominal cramping. She denied fever or weight loss but endorsed many years of daily non-steroidal anti-inflammatory drug (NSAID) use to manage arthritic pain. Prior work up was notable for fecal calprotectin (FC) of 226 ug/g and normal C-reactive protein of 0.3 mg/dL. Colonoscopy revealed moderate patchy erythema with tiny ulcerations throughout the colon with notable rectal sparing (Figure 1). The appearance of the ulcerations combined with the patient's history of uveitis and psoriatic arthritis suggested a diagnosis of Crohn’s colitis. However, biopsies revealed dramatic and diffuse thickening of the subepithelial collagen layer with entrapment of inflammatory cells and capillaries, and an accompanying moderate increase in intraepithelial lymphocytes. The patient was treated for CC with complete NSAID cessation and a course of Budesonide 9 mg daily. At six week follow up she reported complete resolution of diarrhea within 3 days of Budesonide initiation. Discussion: Although ulcerative CC is rare, it has a strong association with NSAID use compared to non-ulcerative CC (61% vs. 78%). Clinical remission rates with Budesonide treatment are high, anywhere from 57% to 100%. Clinical remission occurs quickly, typically in less than 7 days, as was the case with our patient. Given her comorbidities and elevated FC, the possibility of CC and inflammatory bowel disease (IBD) co-occurrence was considered, However, multiple studies have shown elevated FC levels in microscopic colitis compared to controls. Furthermore, CC is usually followed by development of IBD, or years after IBD treatment with tumor necrosis factor-alpha inhibitors. This case illustrates a rare manifestation of CC with ulceration in a clinical context otherwise consistent with Crohn’s colitis.Figure 1.: Figure 1a: Ulcerated mass in cecum as seen on initial colonoscopy. Figure 1b: Cecum on repeat colonoscopy one month later with marked improvement in ulcerations.

СКРИНИНГ КОЛОРЕКТАЛЬНОГО РАКА У СОТРУДНИКОВ МВД РОССИИ ПО РЕСПУБЛИКЕ ТАТАРСТАН. ПЕРВЫЕ РЕЗУЛЬТАТЫ И ПЕРСПЕКТИВЫ РАЗВИТИЯ

Background. Colorectal cancer is one of the most common cancers. The medical society continues to search for evidence-based colorectal cancer screening methods. Aim. The aim of the study was to evaluate the effectiveness of colorectal cancer screening in MIA employees using a preliminary questionnaire. The role of questionnaires in informing patients about modifiable risk factors for colorectal cancer was assessed. Material and methods. Thirty- seven employees of the Ministry of Internal Affairs, undergoing inpatient treatment, aged 40 to 51 years, participated in the study. Study protocol: on admission, patients were asked to fill out a questionnaire to identify risk and exclusion factors. Depending on the results of the questionnaire, each patient was assigned a method of primary colorectal cancer screening – fecal occult blood test or colonoscopy. If small epithelial masses were detected on colonoscopy, a one-stage polypectomy was performed. Results and discussion. Screening examinations allow the detection of precancerous diseases of the colon and, if certain conditions are met and equipment is available, the removal of masses at the initial colonoscopy. Performing a pre-screening survey allows you to identify risk factors for colorectal cancer and to select the right method of screening, as well as to inform patients about opportunities to reduce their likelihood of getting colorectal cancer. Thirty-seven patients were selected for screening. After analysis of the questionnaires, one patient was referred for colonoscopy and 36 patients underwent fecal occult blood tests; 15 of them were found to be positive. As a result, screening colonoscopy was performed in 13 patients, 9 of whom had epithelial masses with different histological structures detected and removed. Conclusion. The first results of screening for colorectal cancer in the Ministry of Internal Affairs allow us to conclude that it is effective for the diagnosis and treatment of precancerous diseases of the colon. The introduction of systematic screening is possible only if certain conditions are met.

S2373 A Case of a Deep Infiltrative Rectal Endometriosis Presenting as a Solitary Ulcer and Lumbosacral Shingles

Introduction: Deep bowel endometriosis is a rare, clinically challenging diagnosis mimicking many gastrointestinal diseases. There are no clear guidelines for the evaluation of patients with suspected bowel endometriosis, therefore a high index of suspicion is warranted. Case Description/Methods: A 39 year old female with a history remarkable for fibroidectomy and constipation presents for rectal bleeding and discomfort for 1 month. In 2012, FOBT was positive and colonoscopy findings were significant for a solitary rectal ulcer. Biopsies showed inflammation. Due to persistent symptoms, a flexible sigmoidoscopy (2013) with repeat biopsies confirmed the diagnosis of deep bowel endometriosis located at the anterior portion of the rectum. Hormonal therapy offered complete resolution of her symptoms. In 2021, due to menopausal symptoms, hormonal therapy was discontinued leading to recurrence of symptoms and new onset right sided lumbosacral shingles. Colonoscopy findings were significant for luminal narrowing and nodularity at the anterior portion of the rectum. Biopsies were nonspecific. Discussion: Given that endometriosis rarely infiltrates the submucosa or mucosa (6.4% of cases), initial colonoscopy and biopsy findings may be nonspecific. Hence, an initial inappropriate diagnosis may occur, demonstrating how challenging this diagnosis may become. Even though the gold standard for diagnosis is direct laparoscopic visualization or tissue diagnosis, imaging modalities such as transvaginal and transrectal US and MRI may diagnose and determine the extent of deep bowel endometriosis. Response to hormonal treatment in deeply infiltrating bowel endometriosis is unpredictable and may require a surgical approach. The natural course of bowel endometriosis has not been formally established. Some authors describe inactive endometriosis as a nodular and fibrotic lesion associated with adhesions and strictures. This correlated with the findings of our patient's latest colonoscopy. Association of endometriosis with rheumatological and autoimmune disorders have been established, where theories based on genetic dysregulation of immune, adhesion, and inflammatory processes take part in the disease pathology. This may explain the greater likelihood of shingles reactivation, such experienced by our patient, during an immunocompromised state such as menopause. Even though deep bowel endometriosis is poorly understood, a high index of suspicion is crucial to offer patients a correct diagnosis and appropriate treatment options.Figure 1.: Deep bowel endometriosis. (Top, left to right) Colonoscopy findings from 2012 (first 2 images) and 2013 respectively showing an abnormal mucosal lesion in the proximal portion of the anterior rectum. (Bottom, left to right) Colonoscopy findings from 2021 showing mucosal nodularity in the proximal portion of the anterior rectum.

S1767 COVID-19 Infection Masquerading as Inflammatory Bowel Disease

Introduction: Although COVID-19 infection has been associated with GI manifestations like nausea, vomiting, diarrhea, and even transaminitis, there is no known association between this virus and inflammatory bowel disease (IBD). Here we present the case of COVID-19 infection masquerading as IBD. We describe the instance of a COVID-19 patient with hematochezia, found to have histological changes similar to IBD on colon biopsy. Case Description/Methods: A 70 year-old female with PMH of HTN, DM, CAD, COPD, and recently diagnosed poorly differentiated colonic adenocarcinoma with signet ring features (status-post hemicolectomy and chemotherapy), presented to the ED with hypotension in the setting of nausea, vomiting, and diarrhea for 5 days. Patient had been started on chemotherapy two weeks prior and was found to have a blood pressure of 76/53, but was afebrile with no signs of tachycardia or hypoxia. Labs were significant for a white blood cell count of 0.67 (absolute neutrophil count 247), platelets of 115, lactate of 0.9, potassium of 6.2, BUN/creatinine of 88/5.6, and CRP of 20.78. COVID-19 PCR was positive. Abdominal CT identified non-specific ileitis, and GI was consulted due to concern for neutropenic enteritis and ileus. During the hospital stay, she developed hematochezia with a drop in hemoglobin. C. diff and GI PCR were negative. A colonoscopy was performed which showed patchy areas of edema, erythema, and ulceration (Figure 1B). Colon biopsies revealed crypt abscesses, consistent with IBD (Figure 1C). However, prior colonoscopy 4 months ago, which identified colon cancer, did not find any evidence of IBD (Figure 1A). Patient clinically declined, ultimately dying of acute hypoxic respiratory failure. Discussion: Given this patient’s age and the fact that she had previously had a colonoscopy that did not show evidence of crypt abscesses, it is unlikely she developed a new diagnosis of inflammatory bowel disease in the interim. It is more likely that the crypt abscesses noted on colon biopsy were due to COVID-19 infection. One study found that of 651 patients with COVID-19, 11.4% exhibited GI symptoms, most often developing acute gastritis or enteritis. We present this case to raise awareness of an unprecedented phenomenon in COVID-19 infection.Figure 1.: Figure 1a: Ulcerated mass in cecum as seen on initial colonoscopy. Figure 1b: Cecum on repeat colonoscopy one month later with marked improvement in ulcerations.

S2947 A Case of Small Bowel Neuroendocrine Tumor Presenting With Elevated Fecal Calprotectin

Introduction: Fecal calprotectin (FC) is a marker of intestinal inflammation most useful in the management of inflammatory bowel diseases (IBD). It is mostly found in the cytoplasm of granulocytes, and to a lesser extent, monocytes. Conditions such as diverticular disease, Microscopic colitis, and Graft versus Host Disease have been associated with elevated FC levels. Historically, this calcium and zinc binding protein has been used to distinguish between IBD and functional bowel disease. We find that any mechanism causing gut mucosal injury can lead to increased migration of neutrophils into the gut lumen, with eventual release of calprotectin by these leukocytes. Gastrointestinal malignancy, particularly colorectal cancer, is one such entity that has been studied to show elevated FC. On the other hand, no cases of neuroendocrine tumors (NET) of the gastrointestinal tract with elevated FC have been reported. Case Description/Methods: Our patient is a healthy 48-year old male who presented to gastroenterology clinic for evaluation of abdominal cramping and loose stools. Initial EGD and colonoscopy with biopsies were normal. His symptoms persisted and stool studies resulted an elevated FC of 595 μg/g (normal 0-120 μg/g). CT enterography showed a small bowel stricture near the ileocecal valve (Figure 1). Suspecting Crohn’s disease, we performed a push enteroscopy and repeat colonoscopy with biopsy-once again which were negative. Subsequent laparoscopic resection of small bowel, 12.5 x 5.0cm in diameter, was performed. A 1.0 x 1.0 x 0.4cm well-circumscribed tan mass was identified within the aforementioned small bowel stricture. Pathology sent was consistent with well-differentiated neuroendocrine tumor. Patient had resolution of symptoms and follows with oncology for surveillance. Discussion: FC is a biomarker of gastrointestinal inflammation that can be elevated in multiple conditions. The most studied medical pathologies linked with elevated FC include IBD, infectious gastroenteritis/colitis, microscopic colitis, and diverticular disease. Perhaps due to the wide use of other neuroendocrine biomarkers such as Chromogranin A and 5-hydroxyindoleacetic acid, coupled with the infrequency of small bowel NETs, FC level correlation has not been investigated. Neuroendocrine tumors of the small bowel are uncommon and often present with vague symptoms and metastatic disease. The differential diagnosis for unexplained elevated FC remains broad and it should include small bowel malignancies such as neuroendocrine tumors.Figure 1.: Coronal view of CT enterography showing small bowel stricture and dilated proximal small bowel.

S2418 Crohn’s Colitis Mimicking Ischemic Colitis: A Case Report

Introduction: Crohn’s disease (CD) can mimic ischemic colitis (IC) in the elderly. Here we present an elderly male diagnosed with CD when IC was initially suspected, and further evaluation revealed that CD was the primary diagnosis. Case description/methods: A 69-year-old male with a history of coronary artery disease with recent percutaneous coronary angioplasty & stent placement on aspirin and clopidogrel presented with hematochezia. He had an acute onset of a large amount of rectal bleeding and denied any other symptoms or having prior hematochezia or chronic diarrhea. Exam noted for hemodynamic stability with no tenderness to palpation of abdomen. Hemoglobin was 10.3 from 17 (Normal [N]: 13.5-17.5 gm/dl). Clinically suspected to have IC. Esophagogastroduodenoscopy (EGD) showed a small superficial non-bleeding gastric ulcer, gastritis, and duodenitis, and no stigmata of recent bleeding. Colonoscopy revealed three large deep ulcers in the proximal descending colon, splenic flexure, and distal transverse colon, with the largest ulcer measuring 50 mm. These ulcers were characterized by heaped up margins with some reactive granulation tissue, suggestive of chronicity. Biopsies showed focal acute cryptitis and diffuse lymphoplasmacytic inflammation in lamina propria without architectural distortion. CT angiography abdomen and pelvis showed widely patent arterial vasculature. Clopidogrel was held for 2 weeks to check healing of ulceration. Repeat colonoscopy showed similar findings, without improvement of ulcerations. Repeat colonic biopsies showed chronic moderately active colitis with ulceration, cytomegalovirus staining was negative. Fecal calprotectin was >3000 [N: < 49 ug/g]. C-reactive protein was 63 [N: < 9 mg/L]. MR Enterography with no small bowel disease but noted hyperenhancement and thickening in the ascending and transverse colon. The initial findings, work up and lack of resolution, was most consistent with CD. Discussion: It is critical to distinguish IC from CD for appropriate management of patients. Differentiating between IC and CD can be challenging in the elderly. Endoscopy and histologic evaluation can aid correct diagnosis. Repeat endoscopy to assess progression or resolution is of utmost importance in differentiating CD from IC, but data is limited on appropriate timing. Lack of follow up endoscopy will most likely lead to misdiagnosis and incorrect management of the underlying pathology. Thus, a high index of suspicion must be maintained when discerning CD from IC.Figure 1.: A: Initial colonoscopy showing heaping upped margins of the splenic flexure ulcerations. B: Repeat colonoscopy showing deep colonic ulceration with heaped up margins at the area of splenic flexure without any resolution.

S1965 B Adaptive: A Case of Rituximab-Associated Colitis and SARS-CoV-2 Vaccination

Introduction: Rituximab (RTX) is a monoclonal antibody against the CD20 surface antigen on B-Cell lymphocytes and is used in various hematologic and autoimmune conditions. Our case describes a patient on RTX therapy with pancolitis that coincided with SARS-CoV-2 vaccination (Moderna-mRNA1273). We attempt to explore a potential correlation of mRNA vaccination platforms, RTX therapy and new onset colitis. Case description/methods: A 49 year old male presented with 6 weeks of watery, non-bloody diarrhea, right upper quadrant pain, >10 pound weight loss and fever. History was significant for stage IVa follicular lymphoma in remission on RTX maintenance therapy, splenectomy and SARS-CoV-2 vaccination (Moderna mRNA-1273) 2 days prior to onset of diarrhea. Infectious work up was negative and CT imaging demonstrated diffuse colonic wall thickening with new interval adjacent pancolonic fat stranding. Initial colonoscopy demonstrated diffuse scattered clean based ulcers between 1-8 mm in size throughout the colon and terminal ileum. Biopsies revealed active chronic ileitis with eosinophils, occasional crypt abscess and crypt destruction negative for HSV, CMV or signs of recurrent lymphoma. He was then treated with oral budesonide, bentyl and loperamide but returned 6 weeks later without any relief in abdominal pain or diarrhea. Repeat colonoscopy demonstrated circumferential hyperemia/edema with apthous ulcers throughout the colon. We plan to treat as a Crohn's patient with corticosteroid induction and trial Vedolizumab for maintenance of remission. Discussion: The novel use of mRNA vaccines has been noted to be game changing in its production time as well as its effectiveness at preventing COVID-19 illness. The mechanism of immunity is proposed to be a combination of generation of neutralizing antibodies and T-helper cell activation. To our knowledge, mRNA-1273 has not directly caused colitis. Literature also describes occurrences of fulminant colitis in patients on RTX therapy and is believed to be secondary to dysregulation caused by depletion of CD20+ B cells and upregulation of autoreactive T-cells. While RTX induced colitis may arise de novo, there may be a correlation between the immunogenicity of mRNA vaccines like mRNA-1273 and the induction of colitis in patients while on immunosuppressants. This case demonstrates the increased need for further evaluation of the pathogenesis of RTX induced colitis as well as the immunogenic response seen in COVID-19 vaccination platforms.

Clinical and endoscopic characteristics of post-colonoscopy colorectal cancers detected within 10 years after a previous negative examination.

Abstract Background and study aims We sometimes encounter colorectal cancer (CRC) that is discovered during the time interval between initial colonoscopy and the recommended follow-up examination. Although several studies reported such cases of CRC, most were based on registry data, which implied that the endoscopic quality was not consistent or guaranteed. We aimed to clarify these clinical and endoscopic characteristics at our high-volume center where a retrospective survey could be precisely performed. Patients and methods We retrospectively analyzed patients with CRC who underwent endoscopic resection or surgery from April 2002 to December 2010, categorizing them into two groups: a “study group” of patients with a negative colonoscopy during the previous 10 years, and a “control group” of patients without a previous colonoscopy or with a previous colonoscopy more than 10 years prior. Results A total of 2042 patients had CRC, among which 55 patients were classified into the study group and the remaining 1989 into the control group. The CRC cases in the study group showed a significant association with smaller (&lt; 30 mm) tumor size (odds ratio [OR] 2.3; 95 % confidence interval [CI] 1.3–4.0) and proximal tumor site (OR 1.7; 95 %CI 0.9–2.9). In addition, right-sided and depressed-type T1 CRCs were significantly more common in the study group. Conclusions Tumor size and location were associated with CRCs detected within 10 years after the negative examination. In addition, depressed-type T1 CRCs were more common. Therefore, we should pay more attention to small, right-sided, or depressed-type tumors in daily colonoscopy.

A sex-specific propensity-adjusted analysis of colonic adenoma detection rates in a screening cohort

The prevalence of colorectal adenoma and advanced adenoma (AA) differs between sexes. Also, the optimal age for the first screening colonoscopy is under debate. We, therefore, performed a sex-specific and age-adjusted comparison of adenoma, AA and advanced neoplasia (AN) rates in a real-world screening cohort. In total, 2824 asymptomatic participants between 45- and 60-years undergoing screening colonoscopy at a single-centre in Austria were evaluated. 46% were females and mean age was 53 ± 4 years. A propensity score for being female was calculated, and adenoma, AA and AN detection rates evaluated using uni- and multivariable logistic regression. Sensitivity analyses for three age groups (group 1: 45 to 49 years, n = 521, 41% females, mean age 47 ± 1 years; group 2: 50 to 54 years, n = 1164, 47% females, mean age 52 ± 1 years; group 3: 55 to 60 years, n = 1139, 46% females, mean age 57 ± 2 years) were performed. The prevalence of any adenoma was lower in females (17% vs. 30%; OR 0.46, 95% CI 0.38–0.55; p < 0.001) and remained so after propensity score adjustment for baseline characteristics and lifestyle factors (aOR 0.52, 95% CI 0.41–0.66; p < 0.001). The same trend was seen for AA with a significantly lower prevalence in females (3% vs. 7%; OR 0.38, 95% CI 0.26–0.55; p < 0.001) that persisted after propensity score adjustment (aOR 0.54, 95% CI 0.34–0.86; p = 0.01). Also, all age-group sensitivity analyses showed lower adenoma, AA and AN rates in females. Similar numbers needed to screen to detect an adenoma, an AA or AN were found in female age group 3 and male age group 1. Colorectal adenoma, AA and AN were consistently lower in females even after propensity score adjustment and in all age-adjusted sensitivity analyses. Our study may add to the discussion of the optimal age for initial screening colonoscopy which may differ between the sexes.

Long-term cumulative incidence of metachronous advanced colorectal neoplasia after colonoscopy and a novel risk factor: a cohort study.

Long-term cumulative incidence of and risk factors for metachronous advanced colorectal neoplasia, including both advanced colorectal adenoma (≥10 mm, or with villous or high-grade dysplasia) and colorectal cancer, are critical for surveillance strategies. The aim of this study was to determine the cumulative incidence of metachronous advanced colorectal neoplasia and its risk factors. A retrospective cohort study was conducted on 6720 consecutive individuals who underwent general health check-ups and colonoscopy. Colorectal adenomas at initial colonoscopy were categorized as low-risk (1-2 small [<10 mm] tubular adenomas) or high-risk adenoma (≥3 tubular adenomas of any size; at least one adenoma ≥10 mm; or villous adenoma or adenoma with high-grade dysplasia). Kaplan-Meier estimates and hazard ratio by Cox-proportional hazard regression were calculated. The cumulative incidence (95% confidence interval [CI]) of metachronous advanced colorectal neoplasia at 5 and 10 years was 5.7% [4.6-7.1], and 11% [8.9-14] in the low-risk adenoma group, and 10% [8.6-13], and 17% [14-21] in high-risk adenoma group, respectively. Adjusted hazard ratio [95% CI] of low-risk adenoma (vs. no colorectal adenoma), high-risk adenoma (vs. no colorectal adenoma), current smoking and positive fecal immunochemical test were 1.34 [1.04-1.74], 1.94 [1.48-2.55], 1.55 [1.2-2.02] and 1.69 [1.35-2.1], respectively. Adjusted hazard ratio [95% CI] of positive fecal immunochemical test was 1.88 [1.29-2.74] in those with normal colonoscopy. Both low-risk and high-risk adenomas confer substantial risk for metachronous advanced colorectal neoplasia at 10 years. Positive fecal immunochemical test was a significant risk factor for metachronous advanced colorectal neoplasia despite normal colonoscopy.

Safety of low-volume PEG-asc bowel cleansing preparation for colonoscopy: identifying patients at risk for hypokalemia in a prospective cohort study.

Background and study aims The aim of bowel cleansing preparation should be high-quality results and conformance with safety standards. Previously, we reported that hypokalemia occurred in 23.6 % of patients after bowel preparation in a high-risk population on diuretics or hospitalized and referred for colonoscopy. Here we report on a prospective study in a non-selected colonoscopy cohort to identify patients at risk of developing hypokalemia before and after bowel cleansing with low-volume polyethylene glycol with ascorbic acid (PEG-asc). Patients and methods From January 1 to July 31, 2016, we included all patients undergoing colonoscopy in our institution. Prevalences of hypokalemia before and after PEG-asc bowel cleansing for colonoscopy were calculated and risk factors for developing hypokalemia after PEG-asc bowel cleansing were identified. Results In total, 2011 patients were included in the analysis. Of these, 0.8 % had hypokalemia before bowel cleansing with PEG-asc. After bowel preparation, 5.4 % developed hypokalemia. Of the patients, 281 were considered to have “high cardiac risk.” The combination of “high cardiac risk” and hypokalemia was present in 1 % of the initial colonoscopy population. Female sex, colorectal cancer diagnosis, and thiazide use were found to be significant predictors for hypokalemia after use of PEG-asc. No arrhythmias or serious adverse events due to hypokalemia occurred. Conclusions Physicians referring patients for colonoscopy should be aware that “high cardiac risk” patients and those on thiazide diuretics undergoing bowel cleansing for colonoscopy are a risk of developing post-cleansing hypokalemia but it remains to be determined whether their risk of developing life-threatening arrhythmias is truly increased.