Siwan Thomas-Gibson

St. Mark's Hospital, Harrow, England, United Kingdom

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Publications (66)290.77 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Although colonoscopy is considered the optimal procedure for bowel cancer screening, it remains an imperfect tool for cancer prevention, due to missed adenomas and early cancers. Optimal imaging modalities, innovative scopes and accessories (cap-assisted colonoscopy) have attempted to decrease the adenoma miss rate. Adenoma detection rates (ADR) have been shown to be a key performance indicator METHODS: Endocuff-vision is a simple accessory mounted at the end of the scope with a proximal row of 6mm length soft plastic, finger-like projections. During scope insertion, these projections invert towards the shaft of the tube and during withdrawal they evert to hold back the colonic folds augmenting the forward endoscopic views. ADRs were recorded and evaluated for screening colonoscopy procedures before and after introduction of Endocuff-vision.
    Gut 06/2014; 63(Suppl 1):A152-A153. · 10.73 Impact Factor
  • Gastroenterology 01/2014; 146(5):S-118. · 12.82 Impact Factor
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    ABSTRACT: To validate the delivery and efficacy of the national laparoscopic colorectal surgery "training the trainer" (Lapco TT) curriculum. The National Training Programme in Laparoscopic Colorectal Surgery designed the Lapco TT curriculum to improve, standardize, and benchmark the quality of training. Evidence for such courses rarely extends beyond subjective feedback. The Lapco TT curriculum tailors key teaching skills for laparoscopic colorectal surgery: training structure, skills deconstruction, trainer intervention, and performance enhancing feedback. Ten Lapco TT courses were delivered to 65 national Lapco trainers since 2010. The course was validated at Kirkpatrick's 4 levels of evaluation: (i) pre- and post-course interviews reflecting initial reaction; (ii) training quality assessment on simulated scenarios using the Structured Training Trainer Assessment Report (STTAR) tool; (iii) follow-up interviews at 4 to 6 months; and (iv) delegate performance ratings, by their trainees, using the mini-STTAR and the delegates' trainees learning curves before and after the course. There were significant improvements in training in the post-course simulated scenario, especially in the "set" (P < 0.001). Delegates described improved framework and structure in their native training environment, which aided difficult training situations. Findings mirrored in performance ratings by their trainees: overall (4.37 vs 4.46, P = 0.040), agreed learning points (3.65 vs 4.00, P = 0.042), encouraged self-reflection (3.67 vs 3.94, P = 0.046), and encouraged team awareness (3.53 vs 4.05, P = 0.045). The learning curve of delegates' trainees improved after the course. The Lapco TT curriculum improved training performance in the short- and long-term, provided a structured training framework, and enhanced the learning curve of delegates' trainees.
    Annals of surgery 12/2013; · 7.90 Impact Factor
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    ABSTRACT: Serrated polyposis is a condition of the colon characterised by multiple serrated polyps. This review aims to provide a practical guide to the day-to-day management of serrated polyposis including diagnosis, endoscopic identification of serrated polyps, surveillance, the role of endoscopic and surgical management and screening of family members. The literature was searched using Pubmed and Medline databases for the terms "serrated polyp, serrated polyposis, hyperplastic polyposis". English language abstracts were read and the full article was retrieved if relevant to the review. Expert opinion from the authors was also sort. Advances in our knowledge of the molecular pathways involved in serrated polyposis and an improved clinical picture of the disease from retrospective studies have led to better understanding of its pathogenesis and natural history. However there are still areas not answered by the literature, and hence empirical management or expert opinion has to be followed. Improvements in our understanding of serrated polyposis together with improvements in endoscopic equipment and technique have enabled the endoscopist to be at the forefront of managing this condition from diagnosis to endoscopic surveillance and control of the polyps. This article is protected by copyright. All rights reserved.
    Colorectal Disease 11/2013; · 2.08 Impact Factor
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    ABSTRACT: Measuring quality is a current need of medical services either to assess their cost-effectiveness or to identify discrepancies requiring refinement. With the advent of bowel cancer screening and increasing patient awareness of bowel symptoms, there has been an unprecedented increase in demand for colonoscopy. Consequently, there is an expanding open-discussion on missed rates of cancer or precancerous polyps during diagnostic/screening colonoscopy and on the rate of adverse events related to therapeutic colonoscopy. Delivering a quality colonoscopy service is therefore a healthcare priority. Colonoscopy is a multi-step process and therefore assessment of all aspects of the procedure must be addressed. Quality in colonoscopy refers to a combination of many patient-centered technical and non-technical skills and knowledge aiming to patient's safety and satisfaction through a continuous effort for improvement. The benefits of this endless process are hiding behind small details which can eventually make the difference in colonoscopy. Identifying specific quality metrics help to define and shape an optimal service and forms a secure basis of improvement. Τhis paper does not aim to give technical details on how to perform colonoscopy but to summarize what to measure and when, in accordance with the current identified quality indicators and standards for colonoscopy.
    World journal of gastrointestinal endoscopy. 10/2013; 5(10):468-75.
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    ABSTRACT: Introduction Endoscopists are now expected to perform polypectomy routinely. Colonic polypectomy varies in difficulty, depending on polyp morphology, size, location and access. The measurement of the degree of difficulty of polypectomy, based on polyp characteristics, has not previously been described. Objective To define the level of difficulty of polypectomy. Methods Consensus by nine endoscopists regarding parameters that determine the complexity of a polyp was achieved through the Delphi method. The endoscopists then assigned a polyp complexity level to each possible combination of parameters. A scoring system to measure the difficulty level of a polyp was developed and validated by two different expert endoscopists. Results Through two Delphi rounds, four factors for determining the complexity of a polypectomy were identified: size (S), morphology (M), site (S) and access (A). A scoring system was established, based on size (1–9 points), morphology (1–3 points), site (1–2 points) and access (1–3 points). Four polyp levels (with increasing level of complexity) were identified based on the range of scores obtained: level I (4–5), level II (6–9), level III (10–12) and level IV (>12). There was a high degree of interrater reliability for the polyp scores (interclass correlation coefficient of 0.93) and levels (κ=0.888). Conclusions The scoring system is feasible and reliable. Defining polyp complexity levels may be useful for planning training, competency assessment and certification in colonoscopic polypectomy. This may allow for more efficient service delivery and referral pathways.
    Frontline Gastroenterology. 06/2013; 4:244-248.
  • K. Patel, S. Thomas-Gibson, O. D. Faiz, M. D. Rutter
    Gut 01/2013; 62(Suppl 1):A149. · 10.73 Impact Factor
  • Gut 01/2013; 62(Suppl 1):A1. · 10.73 Impact Factor
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    ABSTRACT: BACKGROUND: Colonoscopy reduces colorectal cancer mortality and morbidity principally by the detection and removal of colon polyps. It is important to retrieve resected polyps to be able to ascertain their histologic characteristics. OBJECTIVE: The aim of the study was to evaluate the cause of polyp retrieval failure. DESIGN: Bowel cancer screening colonoscopy data were collected prospectively. SETTING: The Bowel Cancer Screening Program in the National Health Service. PATIENTS: Screening participants were referred to our screening center after a positive fecal occult blood test result. INTERVENTION: A total of 4383 polyps were endoscopically removed from 1495 patients from October 2006 to February 2011. MAIN OUTCOME MEASUREMENTS: The number, size, shape, and location of polyps; polyp removal method; quality of bowel preparation; total examination time; and insertion and withdrawal times in collected data were examined retrospectively. RESULTS: The polyp retrieval rate was 93.9%, and the failure rate was 6.1%, thus 267 polyps were not retrieved. In univariate analysis, factors affecting polyp retrieval failure were small polyp size, sessile polyps, and cold snare polypectomy (P < .001). Polyp retrieval was less successful in the proximal colon (P = .002). In multivariate analysis, polyp size and method of removal were independent risk factors for polyp retrieval failure (P < .001). LIMITATIONS: Retrospective study. CONCLUSION: Small polyp size and cold snare removal were found to be significantly associated with polyp retrieval failure. It was difficult to retrieve small, sessile, and proximal colon polyps. Optical diagnosis could be an efficacious option as a surrogate for histologic diagnosis for these lesions in the near future.
    Gastrointestinal endoscopy 12/2012; · 6.71 Impact Factor
  • Kinesh Patel, Sarah Marshall, Siwan Thomas-Gibson
    Clinical medicine (London, England) 12/2012; 12(6):580-2. · 1.32 Impact Factor
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    ABSTRACT: The development of a structured virtual reality (VR) training curriculum for colonoscopy using high-fidelity simulation. Colonoscopy requires detailed knowledge and technical skill. Changes to working practices in recent times have reduced the availability of traditional training opportunities. Much might, therefore, be achieved by applying novel technologies such as VR simulation to colonoscopy. Scientifically developed device-specific curricula aim to maximize the yield of laboratory-based training by focusing on validated modules and linking progression to the attainment of benchmarked proficiency criteria. Fifty participants comprised of 30 novices (<10 colonoscopies), 10 intermediates (100 to 500 colonoscopies), and 10 experienced (>500 colonoscopies) colonoscopists were recruited to participate. Surrogates of proficiency, such as number of procedures undertaken, determined prospective allocation to 1 of 3 groups (novice, intermediate, and experienced). Construct validity and learning value (comparison between groups and within groups respectively) for each task and metric on the chosen simulator model determined suitability for inclusion in the curriculum. Eight tasks in possession of construct validity and significant learning curves were included in the curriculum: 3 abstract tasks, 4 part-procedural tasks, and 1 procedural task. The whole-procedure task was valid for 11 metrics including the following: "time taken to complete the task" (1238, 343, and 293 s; P < 0.001) and "insertion length with embedded tip" (23.8, 3.6, and 4.9 cm; P = 0.005). Learning curves consistently plateaued at or beyond the ninth attempt. Valid metrics were used to define benchmarks, derived from the performance of the experienced cohort, for each included task. A comprehensive, stratified, benchmarked, whole-procedure curriculum has been developed for a modern high-fidelity VR colonoscopy simulator.
    Annals of surgery 06/2012; 256(1):188-92. · 7.90 Impact Factor
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    ABSTRACT: There is a gap in the formal assessment of technical skills in polypectomy that is now considered an integral part of colonoscopy. Polypectomy has been shown to reduce the incidence of colorectal cancer but does have associated complications. Polypectomy competency assessment should arguably be a part of the certification process for all endoscopists. A polypectomy competency assessment tool (Direct Observation of Polypectomy Skills [DOPyS]) has been developed and its reliability examined. This study examined the ability of the DOPyS to reliably distinguish between endoscopists with different levels of experience, ie, its construct validity. To determine the construct validity of the DOPyS. Videos of 32 polypectomies (endoscopic view only) were collected from 2 expert (> 1000 colonoscopies) endoscopists (17 polyps) and 6 intermediate-level (100-500 colonoscopies) endoscopists (15 polyps). The videos were edited to include only the entire polypectomy procedure, arranged in random order, and assessed blindly by 4 experienced endoscopists, only 2 of whom were familiar with polypectomy assessment by using the DOPyS before scoring. The differences in overall competency scores (range 1-4; competency, scores ≥ 3) for the expert and intermediate groups were compared by using the Fisher exact test. Single center. The analysis suggested that both trained assessors familiar with the DOPyS could reliably distinguish between the expert and intermediate endoscopists (P = .049 and P < .001), with the expert group scoring higher than the intermediate one. For the assessors with no previous experience of the DOPyS, no such difference could be seen (P = .71 and P = .15). Small sample and polyp size. The results of the analysis suggested that the DOPyS could reliably differentiate between polypectomies performed by endoscopists of different levels of experience, but only if the assessors were trained in the use of the assessment tool. Training is therefore required to use this tool reliably.
    Gastrointestinal endoscopy 12/2011; 75(3):568-75. · 6.71 Impact Factor
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    ABSTRACT: Despite its ubiquitous use over the past 4 decades, there is no structured, formal method with which to assess polypectomy. To develop and validate a new method with which to assess competency in polypectomy. Polypectomy underwent task deconstruction, and a structured checklist and global assessment scale were developed (direct observation of polypectomy skills [DOPyS]). Sixty bowel cancer screening polypectomy videos were randomly chosen for analysis and were scored independently by 7 expert assessors by using DOPyS. Each parameter and the global rating were scored from 1 to 4 (scores ≥3 = competency). The scores were analyzed by using generalizability theory (G theory). Multicenter. Fifty-nine of the 60 videos were assessable and scored. The majority of the assessors agreed across the pass/fail divide for the global assessment scale in 58 of 59 (98%) polyps. For G-theory analysis, 47 of the 60 videos were analyzed. G-theory analysis suggested that DOPyS is a reliable assessment tool, provided that it is used by 2 assessors to score 5 polypectomy videos all performed by 1 endoscopist. DOPyS scores obtained in this format would reflect the endoscopist's competence. Small sample and polyp size. This study is the first attempt to develop and validate a tool designed specifically for the assessment of technical skills in performing polypectomy. G-theory analysis suggests that DOPyS could reliably reflect an endoscopist's competence in performing polypectomy provided a requisite number of assessors and cases were used.
    Gastrointestinal endoscopy 06/2011; 73(6):1232-9.e2. · 6.71 Impact Factor
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    ABSTRACT: Introduction Long standing ulcerative colitis (UC) is associated with an increased risk of colorectal cancer (CRC), with a cumulative incidence of about 15% at 30 years. The finding of a colonic stricture in a patient with colitis raises the possibility of neoplasia. Unlike in Crohn's disease, benign strictures in UC are rare and historically have been managed surgically with colectomy, partly due to difficulty of excluding cancer within the stricture. Radical surgery carries a risk of major morbidity including permanent stoma formation and segmental colectomy is currently not considered appropriate due to oncologic risk. The authors aimed to assess the outcome of the patients with benign strictures in UC who were managed non-operatively. Methods Patients who had a colonoscopy between January 2003 and December 2008 at our institution and were found to have a stricture without proven malignancy within a segment of colitis were retrospectively identified from the endoscopic database. Those patients who had a follow-up of more than 24 months were included. Colonoscopy and histopathology reports and clinical notes were reviewed. Results In the study period, 15 patients (6 female, median age 49 years) underwent colonoscopy for UC and were found to have a benign stricture. The median follow-up was 36 months. 14 of 18 strictures were left sided; mean duration of the stricture was 2.9 years (SD 2.1 years) and mean length of the stricture was 3.3 cm (SD 2.8 cm). Only two patients were symptomatic and both underwent endoscopic balloon dilatation. Two others underwent dilatation to allow passage of the colonoscope into the proximal colon. One patient ultimately developed CRC, but not within the strictured area of the colon. Two patients underwent surgery, one for CRC outside the stricture and one for what was revealed to be extrinsic compression secondary to endometriosis. One patient developed minor bleeding following endoscopic dilatation, which was managed conservatively. Conclusion Although uncommon, benign strictures are a recognised complication of long standing UC. Careful and detailed consideration including histological and radiological assessment is needed to rule out dysplasia and malignancy. In this series, the majority of patients did not require intervention as the strictures were asymptomatic and ongoing endoscopic surveillance of the remainder of the colon was possible. Endoscopic balloon dilatation was safe and prevented the need for major surgery in four patients while allowing continued endoscopic surveillance. Reconsideration of the place of conservative management and segmental colectomy in benign UC strictures through larger studies may be appropriate.
    Annual General Meeting of the British Society of Gastroenterology Birmingham United Kingdom; 03/2011
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    ABSTRACT: In vivo optical diagnosis of small colorectal polyps has potential clinical and cost advantages, but requires accuracy and high interobserver agreement for clinically acceptability. We aimed to assess interobserver variability and diagnostic performance of endoscopic imaging modalities in characterizing small colonic polyps. High quality still images of 80 polyps < 1 cm were recorded using white-light endoscopy (WLE), autofluorescence imaging (AFI) and narrow-band imaging with and without magnification (NBI and NBImag). All images were assessed for quality, prediction of polyp histology, and vascular pattern intensity (with NBI) by nine experienced colonoscopists (four experts in advanced imaging) from five UK centers. Interobserver agreement (kappa statistic), sensitivity, specificity, and accuracy were calculated compared with histopathological findings. Interobserver agreement for predicting polyp histology using NBImag was significantly better for experts (κ = 0.63, substantial) compared with nonexperts (κ = 0.30, fair; P < 0.001), and was moderate for all colonoscopists with WLE, AFI and NBI. Interobserver agreement for vascular pattern intensity using NBI was 0.69 (substantial) for experts and 0.57 (good) for nonexperts. NBImag had higher sensitivity than WLE (experts, 0.93 vs. 0.68, P < 0.001; nonexperts, 0.90 vs. 0.52, P < 0.001) and higher overall accuracy (experts, 0.76 vs. 0.64, P = 0.003; nonexperts 0.61 vs. 0.40, P < 0.001). AFI had worse accuracy than WLE for both expert colonoscopists (0.53 vs. 0.64, P = 0.02) and nonexperts (0.32 vs. 0.40, P = 0.04). Of the imaging modalities tested, NBImag appeared to have the best overall accuracy and interobserver agreement, although not adequate for in vivo diagnosis. NBI and AFI did not have better sensitivity, specificity, or accuracy compared with WLE.
    Endoscopy 02/2011; 43(2):94-9. · 5.74 Impact Factor
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    ABSTRACT: St Mark's Bowel Cancer Screening Centre commenced screening in October 2006 as a contributor to the national programme. The first 35 months' experience is reported. Individuals with a positive faecal occult blood test (FOBT) were offered colonoscopy or alternatives if they had significant comorbidity. All screening data were collected prospectively. Of the 98 815 FOBT kits issued, 42 523 were returned (43% uptake; 20.79% men). In total, 1339/1488 (90%) FOBT-positive participants attended the nurse clinic (57% men). Of these, 1057 had an index colonoscopy, 115 had a computed tomography colonoscopy (CTC) and eight had a flexible sigmoidoscopy. Five hundred and seventeen (44%) procedures were 'normal' (no polyps/cancers). Eighty (6%) individuals had colorectal cancer. The polyp detection rate in index procedures, including colonoscopy, CTC and flexible sigmoidoscopy, was 50%. The adenoma detection rate of all colonoscopies was 62.8%. The median polyp size was 5 (1-80) mm. In total, 1200 colonoscopies were performed by five accredited colonoscopists (96% completion rate). There were 13 (1%) adverse events with < 1 in 500 patients undergoing polypectomy requiring a transfusion. There was one 30-day postsurgical mortality, one perforation and no colonoscopy-related mortality. Almost all 39/40 (97%) patients in the BCS programme felt that the findings were adequately explained compared with 21/32 (64%) elective patients (P < 0.001) within the same unit. At this bowel cancer screening single centre, colonoscopy completion rates were high (unadjusted caecal intubation rate of 96%) and complication rates were low. In contrast to other published data, the uptake and cancer-detection rates were lower.
    Colorectal Disease 01/2011; 14(2):166-73. · 2.08 Impact Factor
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    ABSTRACT: Experts are accurate in differentiating small adenomas from hyperplastic polyps at colonoscopy by using narrow-band imaging (NBI). To prospectively evaluate the effectiveness of an NBI training module on individuals with varying colonoscopy experience. Prospective educational evaluation study. Academic endoscopy unit. Twenty-one participants of varying colonoscopy experience (novices, trainees, and experienced gastroenterologists) and 5 experts in NBI. Participants completed a computer-based test module consisting of 30 NBI polyp images. No feedback was given. They then completed a computer-based training module on the use of NBI in the differentiation of adenomas and hyperplastic polyps. The test module was then completed a second time. Construct validity (the difference in baseline accuracy on the test module between different groups of participants) and content validity (difference in accuracy achieved on the test module before and after training) of the training module. There was a significant difference in the baseline accuracy (P < .001) between experts (0.95; 95% confidence interval [CI], 0.92-0.97), experienced colonoscopists (0.68; 95% CI, 0.68-0.74), trainees (0.75; 95% CI, 0.67-0.82), and novices (0.62; 95% CI, 0.46-0.77). Accuracy increased significantly (P < .001) for all 3 groups after training (novices 0.84; 95% CI, 0.78-0.88, trainees 0.90; 95% CI, 0.84-0.93, and experienced colonoscopists 0.84; 95% CI, 0.76-0.89). After training, the agreement was moderate at least (κ = 0.56 for novices, κ = 0.70 for trainees, and κ = 0.54 for experienced colonoscopists). This study did not assess the accuracy of optical diagnosis in routine clinical practice. A short, computer-based training module can improve the diagnostic accuracy and interobserver agreement for the use of NBI to differentiate adenomas from hyperplastic polyps and could be used for the initial training in optical diagnosis.
    Gastrointestinal endoscopy 01/2011; 73(1):128-33. · 6.71 Impact Factor
  • Gastrointestinal Endoscopy - GASTROINTEST ENDOSCOP. 01/2011; 73(4).
  • A Ignjatovic, J Landy, S Thomas-Gibson, A Hart, B Saunders
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    ABSTRACT: IntroductionUntil recently a finding of low grade dysplasia within a segment of colitis was an indication for colectomy. However, recent literature suggests that well-circumscribed lesions could be managed by endoscopic resection and continued surveillance. The authors aim to evaluate the medium term outcomes of patients with colitis who have had an endoscopic resection of dysplasia within the segment of colitis.Methods Patients who had a surveillance colonoscopy for colitis between 2003 and 2008 and had an endoscopic resection of a dysplastic lesion were retrospectively identified from the endoscopic database. Those who had a follow-up >24 months were included. Colonoscopy and histopathology reports and clinical notes were reviewed.Results19 patients (16 male; median age 69, IQR 60.5–73) meeting the criteria were included. 17 had pancolitis and 2 distal colitis, with median disease duration of 27 years (IQR 18.5–33.5). Median lesion size was 8 mm (IQR 6.5–20) and 17/18 lesions were sessile (Is=11, IIa=7). Two were removed with ESD and the 17/19 with EMR technique. Histology revealed LGD in 16 lesions, HGD in 3. 6 lesions were histologically favoured to be DALMs rather than ALMs. Median follow-up was 33 months (IQR 27–43). No cancers were detected in that time and overall 4/19 patients had recurrence at the site of previous resection with median time to recurrence of 6 months (IQR 3–10.75). All recurrences were treated by endoscopic resection. One patient was found to have HGD 16 months later and underwent restorative pan-proctocolectomy in which no cancer was found.Conclusion Endoscopically resectable well-circumscribed dysplastic lesions within the segment of colitis may be adequately treated by endoscopic resection and close endoscopic surveillance. Longer term follow-up and larger numbers of patients are necessary to confirm this.
    Gut 01/2011; 60(1). · 10.73 Impact Factor
  • Gastrointestinal Endoscopy - GASTROINTEST ENDOSCOP. 01/2011; 73(4).

Publication Stats

483 Citations
290.77 Total Impact Points

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  • 2002–2014
    • St. Mark's Hospital
      Harrow, England, United Kingdom
  • 2008–2013
    • Imperial College London
      • Section of Biosurgery and Surgical Technology
      Londinium, England, United Kingdom
    • St. Mark's Hospital
      Salt Lake City, Utah, United States