Search

There is a rising trend in exploring the capability of inverse reinforcement learning (IRL) in high dimensional demonstrations. Our aim is to recognise human intents from video data within an IRL f...

Summary Background Screening for Barrett's oesophagus relies on endoscopy, which is invasive and few who undergo the procedure are found to have the condition. We aimed to use machine learning techniques to develop and externally validate a simple risk prediction panel to screen individuals for Barrett's oesophagus. Methods In this prospective study, machine learning risk prediction in Barrett's oesophagus (MARK-BE), we used data from two case-control studies, BEST2 and BOOST, to compile training and validation datasets. From the BEST2 study, we analysed questionnaires from 1299 patients, of whom 880 (67·7%) had Barrett's oesophagus, including 40 with invasive oesophageal adenocarcinoma, and 419 (32·3%) were controls. We randomly split (6:4) the cohort using a computer algorithm into a training dataset of 776 patients and a testing dataset of 523 patients. We compiled an external validation cohort from the BOOST study, which included 398 patients, comprising 198 patients with Barrett's oesophagus (23 with oesophageal adenocarcinoma) and 200 controls. We identified independently important diagnostic features of Barrett's oesophagus using the machine learning techniques information gain and correlation-based feature selection. We assessed multiple classification tools to create a multivariable risk prediction model. Internal validation of the model using the BEST2 testing dataset was followed by external validation using the BOOST external validation dataset. From these data we created a prediction panel to identify at-risk individuals. Findings The BEST2 study included 40 diagnostic features. Of these, 19 added information gain but after correlation-based feature selection only eight showed independent diagnostic value including age, sex, cigarette smoking, waist circumference, frequency of stomach pain, duration of heartburn and acidic taste, and taking antireflux medication, of which all were associated with increased risk of Barrett's oesophagus, except frequency of stomach pain, with was inversely associated in a case-control population. Logistic regression offered the highest prediction quality with an area under the receiver-operator curve (AUC) of 0·87 (95% CI 0·84–0·90; sensitivity set at 90%; specificity of 68%). In the testing dataset, AUC was 0·86 (0·83–0·89; sensitivity set at 90%; specificity of 65%). In the external validation dataset, the AUC was 0·81 (0·74–0·84; sensitivity set at 90%; specificity of 58%). Interpretation Our diagnostic model offers valid predictions of diagnosis of Barrett's oesophagus in patients with symptomatic gastro-oesophageal reflux disease, assisting in identifying who should go forward to invasive confirmatory testing. Our predictive panel suggests that overweight men who have been taking antireflux medication for a long time might merit particular consideration for further testing. Our risk prediction panel is quick and simple to administer but will need further calibration and validation in a prospective study in primary care. Funding Charles Wolfson Charitable Trust and Guts UK.

Introduction The outbreak of COVID-19 has differentially affected countries in the world, with health infrastructure and other related vulnerability indicators playing a role in determining the extent of the COVID-19 spread. Vulnerability of a geographical region/country to COVID-19 has been a topic of interest, particularly in low- and middle-income countries like India to assess the multi-factorial impact of COVID-19 on the incidence, prevalence or mortality data. Datasets and Methods Based on publicly reported socio-economic, demographic, health-based and epidemiological data from national surveys in India, we compute contextual, COVID-19 Vulnerability Indices (cVIs) across multiple thematic resolutions for different geographical and spatial administrative regions. These multi-resolution cVIs were used in regression models to assess their impact on indicators of the spread of COVID-19 such as the average time-varying instantaneous reproduction number. Results Our observational study was focused on 30 districts of the eastern Indian state of Odisha. It is an agrarian state, prone to natural disasters and one of the largest contributors of an unprotected migrant workforce. Our analyses identified housing and hygiene conditions, availability of health care and COVID preparedness as important spatial indicators. Conclusion Odisha has demonstrated success in containing the COVID-19 infection to a reasonable level with proactive measures to contain the spread of the virus during the first wave. However, with the onset of the second wave of COVID, the virus has been making inroads into the hinterlands and peripheral districts of the state, burdening the already deficient public health system in these areas. The vulnerability index presented in this paper identified vulnerable districts in Odisha. While some of them may not have a large number of COVID-19 cases at a given point of time, they could experience repercussions of the pandemic. Improved understanding of the factors driving COVID-19 vulnerability will help policy makers prioritise resources and regions leading to more effective mitigation strategies for the COVID-19 pandemic and beyond. WHAT IS ALREADY KNOWN Measuring vulnerability to COVID-19 and other pandemics is a complex and layered subject. In Low-to-Middle-Income Country (LMIC) like India, complete reliance on incidence, prevalence or mortality data of the disease may not be the best measure since this data from the health system and DHS in public domain is limited. ADDED VALUE OF THIS STUDY To our knowledge, this is the first study at the district level concerning the COVID-19 situation in Odisha, characterized by a large tribal and migrant population. We defined vulnerability through relevant socio-economic domains that have an influence on mitigation strategies. Although we applied our methods to the districts of Odisha, we believe they can be used in other LMIC regions. IMPLICATIONS OF THE FINDINGS Regions with higher overall or theme-specific vulnerability index might experience potentially severe consequences of the COVID-19 outbreak demanding precise, dynamic and nimble policy decisions to prevent a potentially dire situation.

India has seen a surge of SARS-CoV-2 infections and deaths in early part of 2021, despite having controlled the epidemic during 2020. Building on a two-strain, semi-mechanistic model that synthesizes mortality and genomic data, we find evidence that altered epidemiological properties of B.1.617.2 (Delta) variant play an important role in this resurgence in India. Under all scenarios of immune evasion, we find an increased transmissibility advantage for B.1617.2 against all previously circulating strains. Using an extended SIR model accounting for reinfections and wanning immunity, we produce evidence in support of how early public interventions in March 2021 would have helped to control transmission in the country. We argue that enhanced genomic surveillance along with constant assessment of risk associated with increased transmission is critical for pandemic responsiveness.One Sentence SummaryAltered epidemiological characteristics of B.1.617.2 and delayed public health interventions contributed to the resurgence of SARS-CoV-2 in India from February to May 2021.

Modeling the dynamics of COVID-19 pandemic spread is a challenging and relevant problem. Established models for the epidemic spread such as compartmental epidemiological models e.g. Susceptible-Infected-Recovered (SIR) models and its variants, have been discussed extensively in the literature and utilized to forecast the growth of the pandemic across different hot-spots in the world. The standard formulations of SIR models rely upon summary-level data, which may not be able to fully capture the complete dynamics of the pandemic growth. Since the disease spreads from carriers to susceptible individuals via some form of contact, it inherently relies upon a network of individuals for its growth, with edges established via direct interaction, such as shared physical proximity. Using individual-level COVID-19 data from the early days (January 30 to April 15, 2020) of the pandemic in India, and under a network-based SIR model framework, we performed state-specific forecasting under multiple scenarios characterized by the basic reproduction number of COVID-19 across 34 Indian states and union territories. We validated our short-term projections using observed case counts and the long-term projections using national sero-survey findings. Based on healthcare availability data, we also performed projections to assess the burdens on the infrastructure along the spectrum of the pandemic growth. We have developed an interactive dashboard summarizing our results. Our predictions successfully identified the initial hot-spots of India such as Maharashtra and Delhi, and those that emerged later, such as Madhya Pradesh and Kerala. These models have the potential to inform appropriate policies for isolation and mitigation strategies to contain the pandemic, through a phased approach by appropriate resource prioritization and allocation.

Susceptible-Exposed-Infected-Removed (SEIR)-type epidemiologic models, modeling unascertained infections latently, can predict unreported cases and deaths assuming perfect testing. We apply a method we developed to account for the high false negative rates of diagnostic RT-PCR tests for detecting an active SARS-CoV-2 infection in a classic SEIR model. The number of unascertained cases and false negatives being unobservable in a real study, population-based serosurveys can help validate model projections. Applying our method to training data from Delhi, India, during March 15-June 30, 2020, we estimate the underreporting factor for cases at 34-53 (deaths: 8-13) on July 10, 2020, largely consistent with the findings of the first round of serosurveys for Delhi (done during June 27-July 10, 2020) with an estimated 22.86% IgG antibody prevalence, yielding estimated underreporting factors of 30-42 for cases. Together, these imply approximately 96-98% cases in Delhi remained unreported (July 10, 2020). Updated calculations using training data during March 15-December 31, 2020 yield estimated underreporting factor for cases at 13-22 (deaths: 3-7) on January 23, 2021, which are again consistent with the latest (fifth) round of serosurveys for Delhi (done during January 15-23, 2021) with an estimated 56.13% IgG antibody prevalence, yielding an estimated range for the underreporting factor for cases at 17-21. Together, these updated estimates imply approximately 92-96% cases in Delhi remained unreported (January 23, 2021). Such model-based estimates, updated with latest data, provide a viable alternative to repeated resource-intensive serosurveys for tracking unreported cases and deaths and gauging the true extent of the pandemic.

Lately there has been an increasing interest in learning object affordances. This is particularly to address human activity understanding and intention recognition for household robots. However, most existing approaches do not concentrate on imbibing new perceptual models of inferring affordances from visual input. Such models are key for object usage by household robots. Towards this goal, this paper introduces a knowledge based approach to inferring semantic object affordances. This is achieved by integrating ontology and qualitative reasoning within a statistical relational learning scheme. Encouraging results are obtained for the CAD-120 dataset consisting of indoor household activity videos involving human-object interactions.

ObjectivesTo evaluate the effect of four-phase national lockdown from March 25 to May 31 in response to the COVID-19 pandemic in India and unmask the state-wise variations in terms of multiple public health metrics.DesignCohort study (daily time series of case counts).SettingObservational and population based.ParticipantsConfirmed COVID-19 cases nationally and across 20 states that accounted for >99% of the current cumulative case counts in India until 31 May 2020.ExposureLockdown (non-medical intervention).Main outcomes and measuresWe illustrate the masking of state-level trends and highlight the variations across states by presenting evaluative evidence on some aspects of the COVID-19 outbreak: case fatality rates, doubling times of cases, effective reproduction numbers and the scale of testing.ResultsThe estimated effective reproduction number R for India was 3.36 (95% CI 3.03 to 3.71) on 24 March, whereas the average of estimates from 25 May to 31 May stands at 1.27 (95% CI 1.26 to 1.28). Similarly, the estimated doubling time across India was at 3.56 days on 24 March, and the past 7-day average for the same on 31 May is 14.37 days. The average daily number of tests increased from 1717 (19–25 March) to 113 372 (25–31 May) while the test positivity rate increased from 2.1% to 4.2%, respectively. However, various states exhibit substantial departures from these national patterns.ConclusionsPatterns of change over lockdown periods indicate the lockdown has been partly effective in slowing the spread of the virus nationally. However, there exist large state-level variations and identifying these variations can help in both understanding the dynamics of the pandemic and formulating effective public health interventions. Our framework offers a holistic assessment of the pandemic across Indian states and union territories along with a set of interactive visualisation tools that are daily updated at covind19.org.

With only 536 COVID-19 cases and 11 fatalities, India took the historic decision of a 21-day national lockdown on March 25, 2020. The lockdown was first extended to May 3 soon after the analysis of this article was completed, and then to May 18 while this article was being revised. In this article, we use a Bayesian extension of the susceptible-infected-removed (eSIR) model designed for intervention forecasting to study the short- and long-term impact of an initial 21-day lockdown on the total number of COVID-19 infections in India compared to other, less severe nonpharmaceutical interventions. We compare effects of hypothetical durations of lockdown on reducing the number of active and new infections. We find that the lockdown, if implemented correctly, can reduce the total number of cases in the short term, and buy India invaluable time to prepare its health care and disease-monitoring system. Our analysis shows we need to have some measures of suppression in place after the lockdown for increased benefit (as measured by reduction in the number of cases). A longer lockdown from 42–56 days is preferable to substantially ‘flatten the curve’ when compared to 21–28 days of lockdown. Our models focus solely on projecting the number of COVID-19 infections and thus inform policymakers about one aspect of this multifaceted decision-making problem. We conclude with a discussion on the pivotal role of increased testing, reliable and transparent data, proper uncertainty quantification, accurate interpretation of forecasting models, reproducible data science methods, and tools that can enable data-driven policymaking during a pandemic. Our software products are available at covind19.org.

ImportanceIndia has taken strong and early public health measures for arresting the spread of the COVID-19 epidemic. With only 536 COVID-19 cases and 11 fatalities, India – a democracy of 1.34 billion people – took the historic decision of a 21-day national lockdown on March 25. The lockdown was further extended to May 3rd, soon after the analysis of this paper was completed.ObjectiveTo study the short- and long-term impact of an initial 21-day lockdown on the total number of COVID-19 cases in India compared to other less severe non-pharmaceutical interventions using epidemiological forecasting models and Bayesian estimation algorithms; to compare effects of hypothetical durations of lockdown from an epidemiological perspective; to study alternative explanations for slower growth rate of the virus outbreak in India, including exploring the association of the number of cases and average monthly temperature; and finally, to outline the pivotal role of reliable and transparent data, reproducible data science methods, tools and products as we reopen the country and prepare for a post lock-down phase of the pandemic.Design, Setting, and ParticipantsWe use the daily data on the number of COVID-19 cases, of recovered and of deaths from March 1 until April 7, 2020 from the 2019 Novel Coronavirus Visual Dashboard operated by the Johns Hopkins University Center for Systems Science and Engineering (JHU CSSE). Additionally, we use COVID-19 incidence counts data from Kaggle and the monthly average temperature of major cities across the world from Wikipedia.Main Outcome and MeasuresThe current time-series data on daily proportions of cases and removed (recovered and death combined) from India are analyzed using an extended version of the standard SIR (susceptible, infected, and removed) model. The eSIR model incorporates time-varying transmission rates that help us predict the effect of lockdown compared to other hypothetical interventions on the number of cases at future time points. A Markov Chain Monte Carlo implementation of this model provided predicted proportions of the cases at future time points along with credible intervals (CI).ResultsOur predicted cumulative number of COVID-19 cases in India on April 30 assuming a 1-week delay in people’s adherence to a 21-day lockdown (March 25 – April 14) and a gradual, moderate resumption of daily activities after April 14 is 9,181 with upper 95% CI of 72,245. In comparison, the predicted cumulative number of cases under “no intervention” and “social distancing and travel bans without lockdown” are 358 thousand and 46 thousand (upper 95% CI of nearly 2.3 million and 0.3 million) respectively. An effective lockdown can prevent roughly 343 thousand (upper 95% CI 1.8 million) and 2.4 million (upper 95% CI 38.4 million) COVID-19 cases nationwide compared to social distancing alone by May 15 and June 15, respectively. When comparing a 21-day lockdown with a hypothetical lockdown of longer duration, we find that 28-, 42-, and 56-day lockdowns can approximately prevent 238 thousand (upper 95% CI 2.3 million), 622 thousand (upper 95% CI 4.3 million), 781 thousand (upper 95% CI 4.6 million) cases by June 15, respectively. We find some suggestive evidence that the COVID-19 incidence rates worldwide are negatively associated with temperature in a crude unadjusted analysis with Pearson correlation estimates [95% confidence interval] between average monthly temperature and total monthly incidence around the world being −0.185 [−0.548, 0.236] for January, −0.110 [−0.362, 0.157] for February, and −0.173 [−0.314, −0.026] for March.Conclusions and RelevanceThe lockdown, if implemented correctly in the end, has a high chance of reducing the total number of COVID-19 cases in the short term, and buy India invaluable time to prepare its healthcare and disease monitoring system. Our analysis shows we need to have some measures of suppression in place after the lockdown for the best outcome. We cannot heavily rely on the hypothetical prevention governed by meteorological factors such as temperature based on current evidence. From an epidemiological perspective, a longer lockdown between 42-56 days is preferable. However, the lockdown comes at a tremendous price to social and economic health through a contagion process not dissimilar to that of the coronavirus itself. Data can play a defining role as we design post-lockdown testing, reopening and resource allocation strategies.SoftwareOur contribution to data science includes an interactive and dynamic app (covind19.org) with short- and long-term projections updated daily that can help inform policy and practice related to COVID-19 in India. Anyone can visualize the observed data for India and create predictions under hypothetical scenarios with quantification of uncertainties. We make our prediction codes freely available (https://github.com/umich-cphds/cov-ind-19) for reproducible science and for other COVID-19 affected countries to use them for their prediction and data visualization work.

Introduction The EndoringsTM is a distal attachment consisting of two layers of circular flexible rings that evert mucosal folds. Aims; to investigate if Endorings Colonoscopy (ER) improves polyp and adenoma detection compared to standard colonoscopy (SC). Methods This multi-centre, parallel group, randomized controlled trial included screening, surveillance and symptomatic patients. Primary outcome; number of polyps per patient. Secondary outcomes; number of adenomas per patient, adenoma/polyp detection rates and withdrawal times. Results Total of 556 patients (214 females, 342 males) randomized to ER (275) or SC (281). Mean age 67. Colonoscopy completed 532/556 (96%) cases. EndoRings removed in 74/275 (27%) patients. In 66/74 (89%) cases removal was performed due to difficulties with sigmoid intubation. Remainder removed to facilitate retroflexion or polyp removal/retrieval. Total number of polyps in ER limb 571 vs 444 in SC limb. Total number of adenomas in ER limb 361 vs 343 for SC limb. Our study showed a statistically significant difference in the mean number of polyps per patient in both the Intention to Treat (ITT) (1.8 SC vs 2.1 ER, p-value 0.02) and Per Protocol (PP) (1.8 SC vs 2.25 ER, p-value 0.009). There was a trend towards a greater polyp detection rate in the ER colonoscopy (67.5% SC vs 75.2% ER, p-value 0.05). Conclusions Despite the high removal rate of Endorings, there was a statistically significant increase in the mean number of polyps in the ER limb compared to the SC limb. Our study shows promise for the EndoRingsTM device to improve polyp detection.

Background and study aims: There have been significant advances in the management of complex colorectal polyps. Previous failed resection or polyp recurrence is associated with significant fibrosis, making endoscopic resection extremely challenging; the traditional approach to these lesions is surgery. The aim of this study was to evaluate the efficacy of a novel, knife-assisted snare resection (KAR) technique in the resection of scarred colonic polyps. Patients and methods: This was a prospective cohort study of patients, in whom the KAR technique was used to resect scarred colonic polyps > 2 cm in size. Patients had previously undergone endoscopic mucosal resection (EMR) and developed recurrence, or EMR had been attempted but was aborted as a result of technical difficulty. Results: A total of 42 patients underwent KAR of large (median 40 mm) scarred polyps. Surgery for benign disease was avoided in 38 of 41 patients (93 %). No life-threatening complications occurred. Recurrence was seen in six patients (16 %), five of whom underwent further endoscopic resection. The overall cure rate for KAR in complex scarred colonic polyps was 90 %. Conclusions: KAR of scarred colonic polyps by an expert endoscopist was an effective and safe technique with low recurrence rates.

For a collaborative assistive device, human intent recognition (IR) is one of the first and foremost requirements. Formalizing the complex process of human IR in a compact yet expressive mathematical model holds promise. We put forward a Hierarchical Finite State Machine (H-FSM) for human IR within a generalized framework for collaborative assistive devices. Visual and contextual observations drive the H-FSM to different levels of granularity.

Background and study aims Up to 25 % colorectal adenomas are missed during colonoscopy. The aim of this study was to investigate whether the endocuff could improve polyp detection in an organized bowel cancer screening program (BCSP). Patients and methods This parallel group, single-blinded, randomized controlled trial included patients with positive fecal occult blood test (FOBT) who were attending for BCSP colonoscopy. The primary outcome was the number of polyps per patient. Secondary outcomes included the number of adenomas per patient, adenoma and polyp detection rates, and withdrawal times. Results A total of 534 BCSP patients were randomized to endocuff-assisted or standard colonoscopy. The mean age was 67 years and the male to female ratio was 1.8:1. We detected no significant difference in the number of polyps per patient (standard 1.8, endocuff 1.6; P = 0.44), adenomas per patient (standard 1.4, endocuff 1.3; P = 0.54), polyp detection rate (standard 69.8 %, endocuff 70.3 %; P = 0.93), adenoma detection rate (standard 63.0 %, endocuff 60.9 %; P = 0.85), advanced adenoma detection rate (standard 18.5 %, endocuff 16.9 %; P = 0.81), and cancer detection rate (standard 5.7 %, endocuff 5.3 %; P = 0.85). The mean withdrawal time was significantly shorter among patients in the endocuff group compared with the standard colonoscopy group (16.9 vs. 19.5 minutes; P Conclusions This study did not find improved polyp or adenoma detection with endocuff-assisted colonoscopy in the FOBT-positive BCSP population. A shorter withdrawal time with endocuff may reflect improved views and stability provided by the endocuff.Trial registered at ClinicalTrials.gov (NCT02529007).

Object affordances provide useful information related to understanding of human activities. The aim of this paper is to create an ontology for object affordance reasoning that can be shared across different assistive robots operating within the household domain. A novel ontology called O-PrO (Object Property Ontology) consisting of 61 household objects is presented. The ontology can be used for computing cognitive and semantic object affordances.

Background and study aims - Mucosal views can be impaired by residual bubbles and mucus during gastroscopy. This study aimed to determine whether a pre-gastroscopy drink containing simethicone and N-acetylcysteine improves mucosal visualisation.Patients and methods - We conducted a randomized controlled trial recruiting 126 subjects undergoing routine gastroscopy. Subjects were randomized 1:1:1 to receive: A—pre-procedure drink of water, simethicone and N-acetylcysteine (NAC); B—water alone; or C—no preparation. Study endoscopists were blinded to group allocation. Digital images were taken at 4 locations (lower esophagus/upper gastric body/antrum/fundus), and rated for mucosal visibility (MV) using a 4-point scale (1 = best, 4 = worst) by 4 separate experienced endoscopists. The primary outcome measure was mean mucosal visibility score (MVS). Secondary outcome measures were procedure duration and volume of fluid flush required to achieve adequate mucosal views.Results - Mean MVS for Group A was significantly better than for Group B (1.35 vs 2.11, P Conclusions - A pre-procedure drink containing simethicone and NAC significantly improves mucosal visibility during gastroscopy and reduces the need for flushes during the procedure. Effectiveness in the lower esophagus demonstrates potential benefit in Barrett’s oesophagus surveillance gastroscopy.

Endoscopic mucosal resection (EMR) is widely practiced in western countries. Endoscopic submucosal dissection (ESD) is very effective for treating complex polyps but colonic ESD in the western setting remains challenging. We have developed a novel technique of knife-assisted snare resection (KAR) for the resection of these complex lesions. Here we aim to describe the technique, evaluate its outcomes, identify outcome predictors and define its learning curve.We conducted a prospective cohort study of patients who had large and refractory polyps resected by KAR at our institution from 2007 to 2013. Polyp characteristics and procedure details were recorded. Endoscopic follow-up was performed to identify recurrence.A total of 170 patients with polyps 20-170 mm in size were treated by KAR and followed up for a mean of 31.5 months (range 12-84 months). 29% of the polyps were50 mm, 22% had fibrosis from previous unsuccessful interventions and 25% were in the right colon. The perforation rate (1.2%) and bleeding rate (4.7%) were acceptable and managed conservatively in most patients. Recurrence rate after the first attempt was 13.1%. Recurrence was significantly increased by polyp size50 mm (p = 0.008; OR 5.03, 95% CI 1.54-16.48), presence of fibrosis (p = 0.002; OR 6.59, 95% CI 1.97-22.07) and piecemeal resection (p 0.001; OR 0.31, CI 0.078-1.12). Cure rates were 87% after the first attempt, improving to 95.6% with further attempts. En bloc resection rate showed a linear increase and reached almost 80% as the endoscopist's cumulative experience approached 100 cases.This is the largest reported Western series on KAR in the colon. We have demonstrated the feasibility, efficacy and safety of this technique in the treatment of complex polyps, with or without fibrosis and at all sites. KAR has shown better outcomes than either EMR or ESD. We have also managed to identify significant outcome predictors and define the learning curve.

A 54-year-old man presented to our institution with severe dysphagia. Gastroscopy revealed a 10-mm submucosal lesion, with a blue tinge, in the esophagus, 30 cm from the incisors (Fig. 1A). An EUS demonstrated a 10-mm, predominantly fat, hypoechoic, submucosal lesion extending to, but not infiltrating, the muscularis propria. Color Doppler did not identify blood flow through the lesion (Fig. 1B). Endoscopic follow-up was recommended. During follow-up the patient described having progressive dysphagia and odynophagia. Management options of surgery, endoscopic resection, and endoscopic follow-up were discussed. Endoscopic submucosal dissection (ESD) was performed to resect the lesion (Video 1, available online at www.giejournal. org). The procedure was successfully completed without any significant adverse events. The resection specimen showed benign squamous mucosa with an ectatic blood vessel, in keeping with a benign cavernous hemangioma. At follow-up, the patient’s symptoms have improved. The use of ESD of vascular lesions in the esophagus is high risk. However, if the correct submucosal plane is identified, large blood vessels can be avoided. In this case, it became apparent to us at a very early stage that it was a vascular lesion, so dissection was performed in the deeper planes. This case demonstrates the successful treatment of an esophageal submucosal cavernous hemangioma by ESD, avoiding the morbidity associated with esophagectomy.

Introduction One of the factors which make the removal of a polyp challenging is its location in the GI tract. We will present a series of video clips of polyps located in difficult locations to demonstrate the challenges facing the endoscopist and discuss the strategies to circumvent the problem. Three types of polyps are discussed in this abstract: 1. Polyps involving the dentate line 2. Polyps involving the ileo-caecal valve and terminal ileum and 3. Polyps involving the appendiceal orifice. Method Information regarding the nature, location, procedure, recurrence, complication and need for surgery was obtained from a prospective database of polyps more than 2 cm removed between 2010 and 2014. Results 1. Polyp involving the dentate line: Access to these polyps is very difficult. A rich sensory supply of the distal squamous epithelium, difficulty in identifying the distal edge of the polyp and the rich vascular supply in this region makes it challenging. Twelve cases [n = 12] underwent endoscopic resection. The size ranged from 12 mm–150 mm occupying 25% to 80% of the circumference. Laterally spreading tumour –Granular [n = 10] and two were sessile [1s and 1s/2c, n = 2]. 1. Polyp involving the ileo –caecal valve. Here the challenges include difficult access, identifying the margins, ileal extension and risk of perforation. Seven polyps, 30 mm–60 mm in size and involving the ileo- caecal valves were removed endoscopically. LST –G [5], 1s [1] and SSA [1]. 1. Polyp involving the appendicular orifice Decision to resect these polyps should be weighed against the risk of perforation since these polyps could extend into the appendicular canal. Nine cases of polyp involving the appendicular orifice were resected endoscopically with size ranging from 20 mm -100 mm. Six were LST –G[[7]sessile polyp [2]. Histology of the resected polyps was as follows. TVA with LGD [21], TVA with foci of HGD [2], sessile serrated adenoma [4], tubular adenoma with intra mucosal cancer [1], Tubular adenoma [1]. Conclusion Polyps located at the appendicular orifice and ileo -caecal valve have traditionally been managed with right hemicolectomy and polyps at the dentate line with TAR/TEMS. Our data shows that an expert endoscopist can resect these polyps with good clearance and avoid surgery. This makes a case for referral of these polyps to an expert centre. Disclosure of interest None Declared.

Background Currently, various advanced endoscopic techniques are available with varying success rates. These technologies are manufacturer dependent, which has financial implications in the current era of austerity. Acetic acid is a commonly available dye that has been used in the detection of neoplasia within Barrett's esophagus. It has been shown to be effective in detecting neoplasia in high-risk subgroups, but its efficacy in a low-prevalence surveillance population remains unproven. Objective This study aimed to investigate the effectiveness of acetic acid chromoendoscopy in a Barrett's esophagus surveillance population. We aimed to compare the neoplasia yield of acetic acid chromoendoscopy (AAC) with the neoplasia yield from standardized random biopsy (SBP) protocol–guided biopsies in the routine surveillance of patients with Barrett's esophagus. Design Retrospective cohort study. Setting Tertiary referral hospital in the United Kingdom. Patients Patients 18 years of age and older with a diagnosis of Barrett's esophagus undergoing surveillance gastroscopy. Interventions AAC versus standardized random biopsy protocol (SBP) for Barrett's esophagus surveillance. Main Outcome Measurements Neoplasia detection in 2 groups. Results The overall neoplasia detection rates for all grades of neoplasia were 13 of 655 (2%) in the SBP-guided biopsy cohort and 41 of 327 (12.5%) in the AAC cohort ( P = .0001). On per-patient analysis, a 6.5-fold gain in neoplasia detection was seen in the AAC cohort compared with the SBP cohort (0.13 vs 0.02, P = .000). In the SBP cohort, a total of 13 of 655 (2%) neoplasias were detected, of which 3 of 655 patients (0.5%) had low-grade dysplasia, 7 of 655 (1%) had high-grade dysplasia, and 3 of 655 (0.5%) were found to have superficial cancer (T1a/T1b). In the AAC cohort, a total of 41 of 327 neoplasias (12.5%) were found, of which 9 of 327 patients (2.7%) had low-grade dysplasia, 18 of 327 (5.5%) had high-grade dysplasia, and 14 of 327 (4.2%) were found to have superficial cancer. The number of biopsies required to detect 1 neoplasia was 15 times lower in the AAC cohort (40 biopsies) than in the SBP cohort (604 biopsies). On per-biopsy analysis, a 14.7-fold increase in neoplasia detection was seen in the AAC cohort per biopsy compared with the SBP cohort (0.025 vs 0.0017; P = .000). Limitations Not a randomized, controlled study. Conclusions Our study demonstrates that acetic acid detects more neoplasias than conventional protocol-guided mapping biopsies and requires 15 times fewer biopsies per neoplasia detected.

Introduction Endoscopic resection of right-sided colonic polyps carries a higher risk of complications including bleeding and perforation. This risk is heightened in the resection of polyps that are tethered, flat or on background of colitis (complex polyps). In the West, complex polyps in the right colon are frequently managed by endoscopic mucosal resection (EMR) or surgery although recurrence rates can be as high as 20%. Endoscopic submucosal dissection (ESD) is an effective technique in the resection of complex polyps. However, ESD is technically challenging with a long learning curve and carries a significant perforation rate (6% in Eastern series and 17% in Western series) leading to a poor uptake of this technique in the West.[i]We aim to examine the safety and efficacy of a novel technique of knife assisted snare resection (KAR) in resecting complex polyps in the right colon. Methods Data of all KARs undertaken by a single endoscopist in our institution from 2009 to 2015 were prospectively compiled in a pre-designed database and interrogated by independent researchers blinded to the technique. Polyps in the right colon (distal transverse to caecum) were included in the analysis. Polyp characteristics and procedure details were prospectively recorded. Endoscopic follow-up was performed to identify recurrence. Results A total of 52 patients with complex polyps 10–80 mm in size were resected by KAR. The mean follow up time was 35 months. 42% of the polyps were >40 mm in size, and 51% were scarred from previous attempts. The majority of the polyps resected (91%) exhibited flat morphology (Paris Classification IIa, IIa+IIb, IIa+IIc). Table 1 shows the patient baseline and lesion characteristics. There were 2 cases of delayed bleeding (4%) neither of which required surgery. The endoscopic cure rate was 96% after single procedure, improving to 98% with further attempts. Conclusion This is the first reported Western series of KAR of complex polyps in the right colon. Our data demonstrates that this novel technique is safe and effective for resection of complex polyps in the right colon. The recurrence rates are superior to EMR and complication rates are lower than ESD. As the learning curve for KAR is shorter than that for ESD, we believe that this technique is ideal for the Western setting. Reference 1 Saito Y, Uraoka T, Yamaguchi Y, et al. A prospective, multicenter study of 1111 colorectal endoscopic submucosal dissections. Gastrointest Endosc. 2010;72:1217–1225 Disclosure of Interest None Declared

Introduction Rectal polyps extending to the dentate line (RPDL) pose a technical challenge to endoscopic resection due to the narrow lumen, rich venous/haemorrhoidal plexus and proximity to the skin. Conventional snare EMR is challenging due to the restrcited space and lack of precision with the snare. This has led to the use of surgical techniques like TEMS and TAR for resection of RPDLs. K nife A ssisted snare R esection (KAR) allows for precise mucosal incision at the dentate line and the dissection of the polyp from the anorectal junction. We aim to assess the feasibility, safety and efficacy of KAR for RPDLs. Methods This is a prospective observational study of patients who underwent KAR with a mean follow up of 32 months (range 1–83 months). All procedures were done on a day case basis and were carried out under sedation by two endoscopists using high definition gastroscopes with a distal transparent cap. The polyp margin on the anal side was injected with lifting solution consisting of gelofusin, indigo carmine, 1% lignocaine and adrenaline. Haemostasis was maintained using a combination of the endoscopic knife and coag-grasper (Olympus Medical). A mucosal incision was extended around the margins of the polyp, followed by submucosal dissection to facilitate snare deployment to achieve complete polyp resection. Post-procedural antibiotics were not routinely given. Results A total of forty patients (20 female, median age 69 years) underwent KAR for RPDLs over the study period. The polyp characteristics and histology are described in Table 1. The curative resection after a single KAR was achieved in 33 (82.5%) patients. 7 of the 40 patients required further KARs, leading to a total curative resection rate to 97%. The risk factors for multiple resections are polyps measuring >60 mm and encompassing >50% of the circumference (p Conclusion This is the largest reported series of KAR for RPDLs. Our data demonstrates that for Western endoscopists, KAR is a very safe and effective technique in the treatment of RPDLs. As KAR is a viable alternative to full ESD, TEMS and TAR, it will play an increasingly significant role in the management of RPDLs. Disclosure of Interest None Declared

Introduction Up to 25% polyps are missed during colonoscopy. The Endocuff Vision® is a cap with soft flexible arms that attaches to the colonoscope tip and improves views during withdrawal. We have performed the first randomised controlled trial to identify the role of Endocuff Vision® in improving polyp detection. We aim to investigate the impact of Endocuff Vision® assisted colonoscopy on polyp detection, as compared to standard colonoscopy, in the UK Bowel Cancer Screening Programme (BCSP). Methods Single centre, parallel group, randomised controlled trial. Ethics ref: 14/SC/0207. Adopted on UKCRN portfolio (ID: 16985). Patients attending for BCSP colonoscopy were stratified based on attendance for index screening colonoscopy or for polyp surveillance. Within each stratum participants were randomised to either Standard or Endocuff assisted colonoscopy. All procedures were performed by accredited BSCP endoscopists, who have carried out > 5000 colonoscopies and have caecal intubation rates of >90%. Results 534 patients recruited from Sep 2014 to Sep 2015. 3 excluded due to new diagnosis of polyposis syndrome. 531 were included and randomised to the 2 study arms. No significant difference was seen between the 2 groups for the primary endpoint of number of polyps per patient. Secondary endpoints: No significant difference was observed between the 2 groups for adenoma detection rate (ADR) or number of adenomas per patient (Table 1). No significant adverse events were encountered during the study in either arm. The cecal intubation time was not prolonged and patients did not experience any additional discomfort due to the Endocuff Vision. Conclusion In the UK, bowel cancer screening is performed by highly experienced endoscopists. Our results suggest that in expert hands, ADR exceeds 60% even without Endocuff. In such settings, Endocuff Vision did not improve polyp detection rates (PDR) or ADR. However, it did not cause any adverse events, prolong procedure duration or cause additional discomfort. These data demonstrate the safety and feasibility of Endocuff. However, no additional gain was demonstrated in expert hands. Disclosure of Interest None Declared

Introduction Current standard of care for recurrent/residual polyps after previous endoscopic resection is surgery. This study analyses the outcomes of salvage endoscopic resection of polyps with severe scarring following a previously failed endoscopic resection. Method Prospective cohort study of patients referred to a Tertiary-centre for resection of scarred polyps with failed previous endoscopic resection attempts. Resection techniques: ESD knife and Snare combination (Knife Assisted Resection, KAR) or Snare and APC assisted resection (SAR). Results We identified 64 consecutive patients referred to us following a previously failed endoscopic resection attempt. All these patients had severely scarred polyps which were being considered for surgery at the referring centre. The mean polyp size 46 mm (20–150 mm). 83% were left-sided and 17% right–sided. 67% of resections were performed by KAR with mean polyp size 50 mm. 33% of resections were by SAR with mean polyp size 38 mm. Referral to surgery : 2/64 for technically difficult so no attempt made, 5/64 for cancer. Endoscopic follow up and cure : mean follow up of 3 years (range:1–8 years), 97% overall cure rate which was the same for left and right sided lesions as well as KAR and SAR. The only complication was bleeding seen in 3 patients (4.6%). Cost saving: Had all 64 patients been sent for surgery the total cost would have been £343,224. The total cost of the endoscopic approach, including the cost of patients requiring surgery, was £149,820 representing an average cost saving of £3021.94 per patient. Conclusion Severely scarred polyps due to failed previous endoscopic mucosal resection attempts can be successfully treated by experts. The techniques of KAR and SAR are equally effective when used for appropriate polyps. The complication rate is low. Further recurrence after first salvage resection can be treated successfully. Surgery can be avoided in most patients and an endoscopic approach is very cost effective. We would therefore, advocate an aggressive endoscopic resection strategy over surgery when dealing with severely scarred polyps. Disclosure of interest None Declared.

Introduction Low rectal polyps are challenging to resect. We aim to compare safety, feasibility and outcomes of endoscopic resection of low rectal polyps (within 5 cm of dentate line) versus mid to high rectal polyps. Method Cohort study. All patients who had endoscopic resection of rectal polyps >20 mm from 2009 to July 2014 were included. All procedures performed by a single experienced endoscopist. Benign LST-G lesions were resected by conventional EMR technique but polyps close to dentate line, those with scarring, and flat LST-NG lesions were resected either by full ESD or Knife assisted resection technique. Results 181 polyps resected in 179 patients. Avg. patient age 71 years. Mean polyp size 50 mm (20–170 mm). Mean follow up 3 years. Referrals were due to large polyp size, proximity to dentate line or haemorrhoidal bed, scarring or >50% circumference involvement. Polyp characteristics: 61/181(33.7%) >50 mm size, 34/181(18.8%) scarred, 109/181(60.2%) in high rectum and 72/181(39.8%) in low rectum. 110/181(60.8%) resected by ESD and 71/181(39.2%) by EMR. 60/181(33.2%) resected en bloc. Histology showed 8(4.4%) cancers and 27(15%) HGD. There was no significant difference between high and low rectal lesions. Follow up was available for 158. Endoscopic cure rate: 147/158(93%). Of these 124/147(84%) required 1 attempt, 17/147(11.5%) required 2 and 6/147(4.5%) required more than 2 attempts for complete cure. Recurrence/residual polyp after first attempt seen in 30/158 (19%) of patients. Univariate analysis showed that recurrence was significantly linked to size >50 mm, piecemeal resection, low rectal lesions and scarring (Table 1). The complication rate was 14/181(7.7%) which were all managed conservatively. There was 1(0.5%) significant intraprocedural bleed. There were 7(3.9%) delayed bleeds (2 needing transfusion), 1(0.5%) post polypectomy syndrome and 5(2.7%) cases of exposed muscle fibres clipped during the procedure with no further sequelae. There were no factors significantly predictive of complications. Conclusion Rectal polyps referred for resection are generally very large (mean 50 mm). It is safe and feasible to resect very low rectal polyps around the dentate line. We found no difference in complication rates between low and high rectal polyps. Given large sizes and rectal location, the low cancer rate reflects our careful lesion selection. Recurrence is higher in low rectal polyps and those with large size and scarring. However, repeat attempts can achieve complete clearance. Disclosure of interest None Declared.

Introduction Zenker’s diverticulum is a sac-like outpouching of the mucosa and submucosa through an area of muscular weakness between the thyropharyngeus and cricopharyngeus muscles. Traditional treatments have been surgical with open or intraluminal approaches to cricopharyngeal myotomy where the overall complication rate is 9.6%. An alternative approach is to use a flexible endoscope to perform a diverticulotomy. We present a video series to illustrate the principles of flexible endoscopic diverticulotomy. Method We reviewed prospectively collected data of patients with Zenker’s diverticulum referred to our department for endotherapy between January 2014 and January 2015. All patients had Zenker’s diverticulum confirmed on barium swallow. Every procedure was carried out under general anaesthesia by a single endoscopist (PB). A guide wire is inserted into the stomach under direct vision, over which a double-lipped overtube (ZD overtube, ZDO-22–30; Cook Endoscopy, Winston-Salem, North Carolina) is threaded. Under direct vision, the overtube is advanced until the long flap is positioned in the oesophageal lumen and the short flap is in the diverticulum. The septum is clearly visualised and stabilised between the two flaps. The septal mucosa is cut in the middle using a needle knife or diathermy scissors. The mucosal incision is extended until the cricopharyngeal muscle fibres are completely incised. Following this, the cut is extended to approximately 1 cm from the base. Prophylactic endoclips are placed to prevent perforation or bleeding. Patients resume a liquid diet 12 h post procedure. Results A total of 5 patients underwent flexible endoscopic diverticulotomy [female 3, median age 76 years (range 69–84 years)]. 2 patients had previous failed surgical interventions. The mean size of diverticulae was 48 mm (range 30–70 mm) and the mean duration of each procedure was 33 min (range 30–40 mins). 1 patient required an overnight stay as he lived outside our catchment area. There were no procedure related complications or mortality. All patients were able to drink within 12 h and start on a soft diet within 48 h post procedure. Prior to the diverticulotomy, 80% of patients experienced dysphagia with every meal and 60% suffered with regurgitation several times a week. All patients were asymptomatic at follow up at 3. Where 12-month data is available, all patients (3/5) remain asymptomatic. Conclusion In expert hands, flexible endoscopic diverticulotomy is a novel, and safe treatment for Zenker’s diverticulum. It obviates the need for invasive surgery and a majority of patients can be treated on a day-case basis. Initial results are encouraging with no reported complications and excellent short-term success rates. Disclosure of interest None Declared.

Introduction Endoscopic papillectomy is an alternative to radical surgery (10% mortality risk) in the management of ampullary adenomas. Very few centres in the UK have the expertise or experience of performing this procedure and there is certainly no published literature from the UK. We aim to report outcomes after endoscopic papillectomy in a single tertiary endoscopy unit in the UK. Method The prospectively collected data of all patients who underwent endoscopic papillectomy between 2005 and 2015 in Queen Alexandra Hospital, Portsmouth were reviewed. All procedures were carried out by PB (papillectomy) and PG (ERCP) using a standard duodenoscope. The pancreatic and biliary ducts were cannulated. A dilute methylene blue dye was injected into the pancreatic duct prior to papillectomy. Submucosal injection was performed in all cases prior to snare resection of the ampullary neoplasia. 5 Fr pigtail pancreatic stent insertion was attempted in all cases after resection of the neoplasia. Results A total of thirty-five patients were referred for papillectomy but only twenty-two patients (13 female, median age 72 years) underwent a total of 24 papillectomies. En-bloc resection was achieved in 17 patients (77%) with lesion sizes ranging from 8–25 mm (Median 16 mm). Pancreatic stent placement was successful in 82% of all papillectomies. Three patients experienced complications (12.5%); 2 bleeding and 1 acute pancreatitis. There was no procedure related deaths and no one required emergency surgery. There were no local recurrences in 77% of patients. Two patients required 2 attempts to achieve complete clearance of their adenomas. Histology of the resected lesions revealed low grade dysplasia (54.6%), high grade dysplasia (27.2%), cancer (9%), gangliocytic paraganglioma (4.6%), and neuroendocrine tumour (4.6%). Of the two patients who were found to have invasive cancer, the first patient went on to have a pancreaticoduodenectomy and subsequently died of post-operative complications and the second patient was palliated. The total curative resection rate was 86%. Conclusion This is the largest reported UK series of endoscopic papillectomy. Our data demonstrates that this method is a feasible, safe and efficacious means of treating ampullary neoplasia in expert hands. It obviates the need for pancreaticoduodenectomy with its inherent morbidity and mortality. Complications can be serious and expertise is required to deal with them. Disclosure of interest None Declared. References Suzuki K, Kantou U, Murakami Y. Two cases with ampullary cancer who underwent endoscopic excision. Prog Dig Endosc. 1983;23:236–239 De Palma GD. Endoscopic papillectomy: indications, techniques, and results. World J Gastroenterol. 2014;20(6):1537–1543

Introduction Endoscopic resection (ER) is an established effective treatment for Barrett’s neoplasia. ER can lead to recurrence due to residual neoplasia left behind, so it is suggested that all patients should undergo radiofrequency ablation (RFA) after ER. Acetic acid chromoendoscopy has been shown to be an effective method of localising and delineating dysplastic areas of Barrett’s oesophagus and we aim to review the outcome of Acetic Acid guided focal ER without RFA in our patients. Method All ER procedures between January 2005 and November 2014 were recorded in a prospective database which was analysed. Acetic acid guided focal ER was the treatment strategy with the aim of removing all neoplasia visible with acetic acid chromoendoscopy. RFA was not used in this group. Results 112 patients were treated for dysplastic Barrett’s oesophagus or early Barrett’s cancer by ER. The mean age at first procedure was 68 years and 82% of the patients were male. Mean initial Barrett’s length was 5.1 cm. 35 of 112 patients had advanced histological features on the initial ER specimen and were referred for radical cure. The remaining 77 cases showed; intramucosal cancer (IMC) in 46, high grade dysplasia (HGD) in 28 and low grade dysplasia in 3. All 77 cases have follow-up data with a mean duration of 5.4 years. 67 of 77 cases (87%) have sustained eradication of HGIN/IMC after focal ER. 10 patients (13%) developed further neoplasia during follow up. 5/10 patients (6.5%) developed invasive cancer in the residual Barrett’s, all were diagnosed endoscopically and successfully managed with radical curative treatment. Focal ER was successful in a mean of 1.3 procedures per patient (range 1–3). Complication rate was 4% (4 bleeds, 2 strictures). No additional RFA was performed in this patient group. Table 1compares our outcomes with UK HALO registry outcomes where all patients receive RFA. Conclusion Acetic acid guided ER is an effective and safe treatment for dysplastic Barrett’s oesophagus. Progression to cancer after acetic acid guided ER is equivalent to the reported rate of progression after EMR+RFA. 1 Equal rates of sustained eradication of HGIN/IMC are achieved. An acetic acid+ER strategy is potentially much cheaper than an ER+RFA strategy. This data calls for a better stratification of patients who require RFA after ER. Disclosure of interest None Declared. Reference Haidry, et al . Gastroenterology 2013; 145 :87–95

Introduction Use of ESD in the Western setting is limited to a few centres with limited numbers of cases, due to concerns regarding complication rates and no established training pathway. The risks of ESD in the oesophagus are perceived to be high and the consequences disastrous. For this reason, endoscopic mucosal resection (EMR) is the most common technique used to resect early Barrett’s cancer. The drawback of EMR is piecemeal resection and poor interpretation of histology. Method We report our experience of oesophageal ESD in 51 cases and compare our data for EMR (140 cases) over the same period. Results 51 ESD resections for Barrett’s neoplasia were performed between 2006 and 2014. 140 EMR’s were performed in the same period. Mean age 71 years for ESD group and 75 for EMR group. All procedures were undertaken by a single expert endoscopist (PB). Table 1shows patient characteristics and lesion characteristics. The endoscopic cure rate in the ESD group was 83% and the EMR group was 82%. It took a mean of 1.2 procedures in the ESD group and 1.4 procedures in the EMR group. In the ESD group there was a recurrence rate of 3%, in the EMR group 16%. Additional radiofrequency ablation was required in 17% of patients in the ESD group and 34% of patients in the EMR group. There was one perforation in the ESD group which was successfully managed conservatively with endoclips, not requiring surgery. There were 4 cases of bleeding and 3 cases of stricturing managed endoscopically in the EMR group. Conclusion ESD for Barrett’s neoplasia is feasible, safe and effective in Western hands. Our lesion selection data shows that ESD is being used mainly for nodular lesions and cancerous lesions as compared to EMR for flat and non-cancerous lesions. Neoplasia recurrence is higher in EMR vs ESD. This calls for a randomised controlled trial comparing EMR vs ESD for the resection of nodular lesions in Barrett’s neoplasia. Disclosure of interest None Declared.

Introduction Buried Barrett’s’ or Subsquamous Intestinal Metaplasia (SSIM) refers to glands which are ‘buried’ underneath the squamous epithelium. Buried Barrett’s can pose significant diagnostic and surveillance challenges. Buried Barrett’s has mainly been reported in the post ablation context (APC, RFA, PDT). We aim to evaluate its prevalence in patients who are ablation naive, and understand the reasons behind it. Method This is a prospective cohort study. We investigated our Barrett’s database for patients who were referred for endoscopic treatment (EMR) of Barrett’s neoplasia between June 2006 to June 2014. We assessed histology reports before and after endoscopic therapy (EMR), specifically looking for evidence of buried Barrett’s. Biopsy: Biopsies were first obtained from any suspicious looking area. Following this, biopsies were then obtained from the neosquamous area. Finally, random biopsies were obtained. These were sent in separate cassettes. Histopathology was reported by two independent GI pathologists and was prospectively recorded on a central pathology database. Buried Barrett’s was defined as any metaplastic or glandular tissue beneath the squamous epithelium. Pathology specimens were reported by 2 independent, accredited GI pathologists. Results Our study shows that in the pre-EMR cohort, there was an overall prevalence of 12.2% of buried Barrett’s and a 9.1% prevalence of buried Barrett’s with high grade neoplasia (HGD or IMC). Our results in the post EMR cohort shows an overall prevalence of 16.8% of buried Barrett’s with 6.1% prevalence of buried high grade neoplasia (HGD or IMC). This has significant implications for post EMR endoscopic assessment and surveillance. Conclusion Buried Barrett’s and Barrett’s cancer are seen in endotherapy naive patients. This is likely to be related to intensive biopsies. EMR, despite being a non ablation technique, still results in buried Barrett’s and Barrett’s cancer. The overall prevalence of buried Barrett’s is higher than previously reported. We need to be aware of this while assessing Barrett’s patients. Buried Barrett’s glands after ablation (APC/RFA/PDT) are well reported. This is the first study to report on the prevalence of Barrett’s in endotherapy naive patients and in the post EMR cohort. Disclosure of interest None Declared.

Introduction Despite advances in endoscope technology there is still a significant miss rate of neoplastic lesions during gastroscopy. Mucosal views are frequently impaired by residual bubbles and mucus. Method We conducted an RCT in 126 patients attending for routine gastroscopy. Subjects were randomised in a 1:1:1 ratio to receive a pre-procedure drink of water, simeticone and n-acetylcysteine (Group A), water alone (Group B) or no preparation (Group C). Study endoscopists were blinded to group allocation. 4 digital images were taken at pre-defined locations during the procedure – lower oesophagus, upper body, antrum and fundus. Images were rated for mucosal visibility (MV) using a 4 point scale (1 = best, 4 = worst) by 4 blinded experienced endoscopists. Primary outcome measure was mean MV score. Secondary outcome measures were procedure duration and volume of flush required to achieve adequate mucosal views. Results Groups were well matched for age, gender or indication for endoscopy. Mean MV score for group A was significantly better than for group B and group C (p Subgroup analysis of MV scores at each location demonstrated significantly better mucosal visibility in group A compared to group B and group C at all locations (p Conclusion A pre-procedure drink containing simeticone and n-acetlycysteine significantly improves mucosal visibility during routine gastroscopy and reduces the need for flushes during the procedure. This may improve detection of early neoplasia and other pathology during gastroscopy. Subanalysis of separate locations demonstrates significant benefit in the lower oesophagus, demonstrating potential benefit in Barrett’s surveillance procedures. Disclosure of interest None Declared.

Introduction ESD enables large lesions to be resected en bloc. This reduces recurrence, but ESD is technically challenging with high complication rates and hence not widely practiced in the west. We have used a novel Knife Assisted Resection (KAR) technique. We aim to evaluate the outcome of KAR in the treatment of large and refractory colonic polyps and identify polyp features that can predict complications and recurrence after KAR. Methods Cohort study of patients referred to our centre for resection of refractory polyps. All patients who had KAR of colonic polyps >20 mm in size from 2006 to Feb 2013 were included. All procedures were performed by a single experienced endoscopist. The technique starts with submucosal (SM) injection followed by mucosal incision using a dual knife (Olympus KD-650L). This is followed by variable degrees of SM dissection and completion of circumferential mucosal incision. Finally a snare assisted resection is performed either en bloc or piecemeal, depending on the polyp size and extent of SM dissection. Results 127 polyps in 127 patients of mean age 71 years. Mean polyp size 46 mm (20–170 mm). 27% were >50 mm. 27% were scarred from past attempted resection. 26% were in the right colon. En bloc resection: 58/127(46%). Size (p = 0.001) predictor of en bloc resection (88 vs. 12%). The complication rate was 11/127(8.6%) with 5(3.9%) bleeds, 4(3.1%) diathermy damage to muscle fibres and 1(0.78%) perforation. Complications were not linked to polyp size, scarring or resection site. A single patient with perforation required surgery. All other complications were managed endoscopically. The recurrence rate was 14/106(13%). This was significantly higher for polyps >50mm (p = 0.009) and in scarred polyps (p = 0.024) . On sub-analysis of unscarred polyps, polyps ≤50 mm with no scarring had a very low recurrence rate of 3.2% as compared to 25% in polyps >50 mm (p = 0.005) . Factors associated with recurrence Conclusion This is the largest reported western series demonstrating the feasibility, safety and efficacy of KAR for large and refractory polyps, with or without scarring, at all colonic sites. Our data demonstrates that complications of KAR are not related to size but the recurrence rate is. Size >50 mm and scarring seem to be predictors of recurrence. We propose flat polyps 20–50 mm in size as the ideal indication for KAR in the western setting. Disclosure of Interest None Declared.

Introduction The learning curve for ESD in the west is very long, so a hybrid technique has been proposed. The impact of Hybrid ESD (H-ESD) technique on clinical outcome is unclear. We aim to compare the outcome benefits of Multi-piece EMR and H-ESD in the resection of challenging colonic polyps. Methods A Prospective cohort study of endoscopic resection of difficult colonic polyps. Patients were tertiary referrals from experienced endoscopists. EMR was defined as submucosal injection followed by piecemeal snare resection. H-ESD involved submucosal injection before mucosal incision with an ESD knife followed by snare resection of the lesion. Endoscopic follow up was performed. Multiple linear regression analysis was performed using SPSS. Results 347 flat/sessile polyps > 20 mm were resected between 2007–12. Mean follow-up was 1004 days. H-ESD Cohort N = 110/347(32%). Mean size was 45mm(range 10–170). 25/110(23%) were salvage procedures for scarred lesions due to failed EMR attempts by other endoscopists. Endoscopic clearance was achieved in 95.5% of procedures. Need for surgery (n = 4): 1 for perforation and 3 for unexpected cancer. 98.6% showed no evidence of recurrence at endoscopic follow up. EMR cohort N = 237/347(68%). Mean size was 42mm(range 20–150). 11/237(4.6%) were salvage procedures for polyps with scarring. Endoscopic clearance was achieved in 93% of cases. Need for surgery (n = 21): 1 patient for incomplete resection & 20 for suspicion of cancer in EMR specimen. At endoscopic follow up 98% of cases had achieved complete clearance. Risk of recurrence was associated with lesion size > 50 mm & scarring due to previous EMR attempts. This was unaffected by technique (EMR or H-ESD). Perforation/microperforation was more likely in the H-ESD Cohort, but the overall complication rates were similar for H-ESD and EMR cohort. Conclusion Both techniques achieved an excellent overall cure rate for large & challenging polyps. This is the first large series comparing the two techniques and demonstrates that polyp cure rate was equally good with both techniques. H-ESD technique was used more commonly for polyps with significant scarring & was associated with slightly higher perforation rates. Our data does not demonstrate any significant outcome benefit of H-ESD technique over the conventional EMR technique. Disclosure of Interest None Declared

Introduction Buried Barrett’s’ or Subsquamous intestinal metaplasia (SSIM) refers to glands which are ‘buried’ underneath the squamous epithelium. High dose acid suppressive therapy and lack of acid exposure can result in squamous re-epithelialisation over the Barrett’s mucosa. Buried Barrett’s can pose significant diagnostic and surveillence challenges. Data on the prevalance of Buried Barrett’s in endoscopic therapy naive patients is limited. Like wise there is limted data on the prevalance of Buried Barrett’s in patients following EMR. We aim to study and compare the prevalence of Buried Barrett’s in these two groups of patients. Methods Inclusion Criteria: Patients with Barrett’s referred for endoscopic treatment between June 06 and June 12 Patients with Barrett’s dysplasia following EMR procedure. Biopsy: Biopsies were first obtained from any suspicious looking area. Following this, biopsies were then obtained from the neosquamous area. Finally, random biopsies were obtained. These were sent in separate cassettes. Histopathology was reported by two independent GI pathologists and was prospectively recorded on a central pathology database. Buried Barrett’s was defined as any metaplastic or glandular tissue beneath the squamous epithelium. Pathology specimens were reported by 2 independent, accredited GI pathologists. Results Conclusion Our study shows that in the pre-EMR cohort, there was an overall prevalence of 15.7% of buried Barrett’s and a 14.5% prevalence of buried Barrett’s with high grade neoplasia (HGD or IMC). Our results in the post EMR cohort shows an overall prevalence of 33.7% of buried Barrett’s with 9.6% prevalence of buried high grade neoplasia (HGD or IMC) suggesting that a third of patients undergoing EMR for Barrett’s dysplasia harbour buried Barrett’s and a third of these patients harbour high grade neoplasia. This has significant implications for post EMR endoscopic assessment and surveillance. The results from our study shows that there is a need to develop and maintain proficiency in sampling techniques in patients with Barrett’s oesophagus. It also shows that the biopsies particularly from those with dysplasia should be carefully reviewed by gastrointestinal pathologists who devote specific attention to identifying buried Barrett’s and buried dysplasia. Disclosure of Interest None Declared

Introduction Cost effectiveness of Barrett’s surveillance has recently being questioned due to the low neoplasia detection rate. Acetic acid chromoscopy (AAC) has been shown to improve neoplasia detection in Barrett’s oesophagus but not in surveillance population. The aim of this study is to compare the effectiveness of AAC with Cleveland clinic protocol (2 cm quadrantic) guided biopsies at detecting high risk neoplasia during Barrett’s surveillance. Methods Prospective Cohort study comparing two different Barrett’s surveillance strategies. All patients who underwent Barrett’s surveillance between 2008–12 were recorded on a Barrett’s database. All neoplasias were independently reviewed by two GI Pathologists. Barrett’s surveillance patients were randomly allocated to acetic acid chromoscopy lists (cohort B) or protocol guided biopsy (Cohort A) lists. AAC involved targeted biopsy of area of concern & 3 additional biopsies from lower, middle & top end of Barrett’s. Protocol guided were taken as quadrantic biopsies every 2 cm & any visible abnormality. Fisher’s exact test was used for statistical analysis. Results N = 982 Barrett’s surveillance gastroscopy between 2008–12. Median age was 66 years & Median Barrett’s length was 4.5 cm (range: 1–20). Male: Female = 3.3:1 . Protocol guided Cohort A N = 655/982(66.7%). 7/655 (1%) patients were found to have high grade dysplasia (HGD) & 3/655(0.4%) had T-1 cancers with an overall high risk neoplasia detection rate of 10/655(1.5%). Acetic acid Cohort B N = 327/982(33.2%). 18/327(5.5%) patients were found to have HGD & 14/327(4.2%) had T-1 cancers with an overall high risk neoplasia detection rate of 32/327(9.7%). This shows a statistically significant 6.5 fold (p = 0.0001) increased detection of high risk neoplasia with acetic acid guided biopsies as compared to protocol guided biopsies in Barrett’s surveillance. Conclusion This is the first report from a large exclusively Barrett’s surveillance population. Our data demonstrates that acetic acid chromoscopy significantly (6.5 fold) improves the detection of high risk neoplasia in Barrett’s surveillance as compared to the current standard of 2 cm quadrantic biopsies. AAC also results in significantly less number of biopsies taken so overall it will be very cost-effective. This questions the validity of the current standard of non targeted protocol guided biopsies during Barrett’s surveillance. Disclosure of Interest None Declared