Évaluation des compétences en laparoscopie : comparaison de la fiabilité des outils d’évaluation globale et des outils d’évaluation de la confiance

Background: Competence by design (CBD) residency programs increasingly depend on tools that provide reliable assessments, require minimal rater training, and measure progression through the CBD milestones. To assess intraoperative skills, global rating scales and entrustability ratings are commonly used but may require extensive training.  The Competency Continuum (CC) is a CBD framework that may be used as an assessment tool to assess laparoscopic skills. The study aimed to compare the CC to two other assessment tools: the Global Operative Assessment of Laparoscopic Skills (GOALS) and the Zwisch scale. Methods: Four expert surgeons rated thirty laparoscopic cholecystectomy videos. Two raters used the GOALS scale while the remaining two raters used both the Zwisch scale and CC. Each rater received scale-specific training. Descriptive statistics, inter-rater reliabilities (IRR), and Pearson’s correlations were calculated for each scale. Results: Significant positive correlations between GOALS and Zwisch (r = 0.75, p < 0.001), CC and GOALS (r = 0.79, p < 0.001), and CC and Zwisch (r = 0.90, p < 0.001) were found. The CC had an inter-rater reliability of 0.74 whereas the GOALS and Zwisch scales had inter-rater reliabilities of 0.44 and 0.43, respectively. Compared to GOALS and Zwisch scales, the CC had the highest inter-rater reliability and required minimal rater training to achieve reliable scores. Conclusion: The CC may be a reliable tool to assess intraoperative laparoscopic skills and provide trainees with formative feedback relevant to the CBD milestones. Further research should collect further validity evidence for the use of the CC as an independent assessment tool.Contexte : Les programmes de résidence structurés autour de la compétence par conception (CPC) dépendent de plus en plus d’outils qui fournissent des évaluations fiables, nécessitent une formation minimale des évaluateurs et mesurent la progression dans les étapes de la CPC. Pour évaluer les compétences peropératoires, les échelles d’évaluation globale et de confiance sont couramment utilisées mais peuvent nécessiter une formation approfondie. Le Continuum des compétences (CC) est un cadre de la CPC qui peut être utilisé comme outil d’évaluation des compétences laparoscopiques. L’étude visait à comparer le CC à deux autres outils d’évaluation : l’évaluation globale opératoire des compétences laparoscopiques (GOALS) et l’échelle de Zwisch. Méthodes : Quatre chirurgiens experts ont évalué trente vidéos de cholécystectomie laparoscopique. Deux évaluateurs ont utilisé l’échelle GOALS tandis que les deux autres ont utilisé l’échelle Zwisch et le CC. Chacun d’eux avait reçu une formation spécifique à l’échelle utilisée. Des statistiques descriptives, la fiabilité inter-évaluateurs (FIÉ) et des corrélations de Pearson ont été calculées pour chaque échelle. Résultats : Des corrélations positives significatives ont été trouvées entre les échelles GOALS et Zwisch (r=0.75, p<0.001), CC et GOALS (r=0.79, p<0.001), et CC et Zwisch (r=0.90, p<0.001). Le CC avait une fiabilité inter-évaluateurs de 0,74 tandis que les échelles GOALS et Zwisch avaient des fiabilités inter-évaluateurs de 0,44 et 0,43, respectivement. Par rapport aux échelles GOALS et Zwisch, le CC avait la fiabilité inter-évaluateurs la plus élevée et ne nécessitait qu’une formation minimale des évaluateurs pour obtenir des scores fiables. Conclusion : Le CC constituerait un outil fiable pour évaluer les compétences laparoscopiques peropératoires et pour fournir aux stagiaires une rétroaction formatrice pertinente pour les étapes de la CPC. Des recherches supplémentaires devraient être entreprises pour recueillir plus de preuves de validité pour l’utilisation du CC comme outil d’évaluation indépendant

Une occasion d’introduire une réforme : l'impact environnemental des déplacements faits pour se rendre à une entrevue de stage en chirurgie générale

Background: In light of the global climate emergency, it is worth reconsidering the current practice of medical students traveling to interview for residency positions. We sought to estimate carbon dioxide (CO2) emissions associated with travel for general surgery residency interviews in Canada, and the potential avoided emissions if interviews were restructured. Methods: An 8-item survey was constructed to collect data on cities visited, travel modalities, and costs incurred. Applicants to the University of Ottawa General Surgery Program during the 2019/20 Canadian Resident Matching Service (CaRMS) cycle were invited to complete the survey.  Potential reductions in CO2 emissions were modeled using a regionalized interview process with either one or two cities. Results: Of a total of 56 applicants, 39 (70%) completed the survey. Applicants on average visited 10 cities with a mean total cost of $4,866 (95% CI=3,995-5,737) per applicant. Mean CO2 emissions were 1.82 (95% CI=1.50-2.14) tonnes per applicant, and the total CO2 emissions by applicants was estimated to be 101.9 (95% CI=84.0 – 119.8) tonnes. In models wherein interviews are regionalized to one or two cities, emissions would be 57.9 tonnes (43.2% reduction) and 84.2 tonnes (17.4% reduction), respectively. Overall, 74.4% of respondents were concerned about the environmental impact of travel and 46% would prefer to interview by videoconference. Conclusion: Travel for general surgery residency interviews in Canada is associated with a considerable environmental impact. These findings are likely generalizable to other residency programs. Given the global climate crisis, the CaRMS application process must consider alternative structures.Contexte: Compte tenu de la situation d’urgence climatique mondiale, il convient de reconsidérer l’usage actuel selon lequel les étudiants en médecine se déplacent pour se présenter aux entrevues en vue d’obtenir un poste de résidence. Nous avons tenté d’estimer les émissions de dioxyde de carbone (CO2) causées par les déplacements pour les entretiens de résidence en chirurgie générale au Canada, et les émissions potentielles évitées si les entretiens étaient organisés autrement. Méthodes : Un sondage comportant huit questions a été élaboré pour recueillir les données sur les villes visitées, les modalités de voyage et les coûts encourus. Les candidats au programme de chirurgie générale de l’Université d’Ottawa au cours du cycle 2019/20 du Service canadien de jumelage des résidents (CaRMS) ont été invités à y répondre. Les réductions potentielles des émissions de CO2 ont été modélisées à l’aide d’un processus d’entrevue régionalisé avec une ou deux villes. Résultats : Sur un total de 56 candidats, 39 (70 %) ont répondu au sondage. Les candidats ont visité en moyenne 10 villes, pour un coût total moyen de 4 866 dollars (IC 95 % = 3 995-5 737) par candidat. Les émissions moyennes de CO2 étaient de 1,82 (IC 95 % = 1,50-2,14) tonne par candidat, et le total des émissions de CO2 pour l’ensemble des candidats était estimé à 101,9 (IC 95 % = 84,0 - 119,8) tonnes. D’après les modèles où les entrevues sont régionalisées avec une ou deux villes, les émissions seraient respectivement de 57,9 tonnes (43,2 % de réduction) et 84,2 tonnes (17,4 % de réduction). Dans l’ensemble, 74,4 % des personnes interrogées se disent préoccupées par l’impact environnemental des déplacements et 46 % préféreraient que l’entretien se fasse par vidéoconférence. Conclusion : Les déplacements pour les entrevues de résidence en chirurgie générale au Canada ont un impact environnemental considérable. Ces conclusions sont probablement généralisables à d’autres programmes de résidence. Compte tenu de la crise climatique mondiale, il conviendrait d’envisager d’autres modalités d’organisation des entrevuespour le processus de candidatures du CaRMS

Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London

Surgical site infection after gastrointestinal surgery in high-income, middle-income, and low-income countries: a prospective, international, multicentre cohort study

Background: Surgical site infection (SSI) is one of the most common infections associated with health care, but its importance as a global health priority is not fully understood. We quantified the burden of SSI after gastrointestinal surgery in countries in all parts of the world. Methods: This international, prospective, multicentre cohort study included consecutive patients undergoing elective or emergency gastrointestinal resection within 2-week time periods at any health-care facility in any country. Countries with participating centres were stratified into high-income, middle-income, and low-income groups according to the UN's Human Development Index (HDI). Data variables from the GlobalSurg 1 study and other studies that have been found to affect the likelihood of SSI were entered into risk adjustment models. The primary outcome measure was the 30-day SSI incidence (defined by US Centers for Disease Control and Prevention criteria for superficial and deep incisional SSI). Relationships with explanatory variables were examined using Bayesian multilevel logistic regression models. This trial is registered with ClinicalTrials.gov, number NCT02662231. Findings: Between Jan 4, 2016, and July 31, 2016, 13 265 records were submitted for analysis. 12 539 patients from 343 hospitals in 66 countries were included. 7339 (58·5%) patient were from high-HDI countries (193 hospitals in 30 countries), 3918 (31·2%) patients were from middle-HDI countries (82 hospitals in 18 countries), and 1282 (10·2%) patients were from low-HDI countries (68 hospitals in 18 countries). In total, 1538 (12·3%) patients had SSI within 30 days of surgery. The incidence of SSI varied between countries with high (691 [9·4%] of 7339 patients), middle (549 [14·0%] of 3918 patients), and low (298 [23·2%] of 1282) HDI (p < 0·001). The highest SSI incidence in each HDI group was after dirty surgery (102 [17·8%] of 574 patients in high-HDI countries; 74 [31·4%] of 236 patients in middle-HDI countries; 72 [39·8%] of 181 patients in low-HDI countries). Following risk factor adjustment, patients in low-HDI countries were at greatest risk of SSI (adjusted odds ratio 1·60, 95% credible interval 1·05–2·37; p=0·030). 132 (21·6%) of 610 patients with an SSI and a microbiology culture result had an infection that was resistant to the prophylactic antibiotic used. Resistant infections were detected in 49 (16·6%) of 295 patients in high-HDI countries, in 37 (19·8%) of 187 patients in middle-HDI countries, and in 46 (35·9%) of 128 patients in low-HDI countries (p < 0·001). Interpretation: Countries with a low HDI carry a disproportionately greater burden of SSI than countries with a middle or high HDI and might have higher rates of antibiotic resistance. In view of WHO recommendations on SSI prevention that highlight the absence of high-quality interventional research, urgent, pragmatic, randomised trials based in LMICs are needed to assess measures aiming to reduce this preventable complication

Surgical exploration and discovery program: inaugural involvement of otolaryngology – head and neck surgery

Abstract Background There is significant variability in undergraduate Otolaryngology – Head and Neck Surgery (OTOHNS) curricula across Canadian medical schools. As part of an extracurricular program delivered jointly with other surgical specialties, the Surgical Exploration and Discovery (SEAD) program presents an opportunity for medical students to experience OTOHNS. The purpose of this study is to review the participation and outcome of OTOHNS in the SEAD program. Methods The SEAD program is a two-week, 80-hour, structured curriculum that exposes first-year medical students to nine surgical specialties across three domains: (1) operating room observerships, (2) career discussions with surgeons, and (3) simulation workshops. During observerships students watched or assisted in surgical cases over a 4-hour period. The one-hour career discussion provided a specialty overview and time for students’ questions. The simulation included four stations, each run by a surgeon or resident; students rotated in small groups to each station: epistaxis, peritonsillar abscess, tracheostomy, and ear examination. Participants completed questionnaires before and after the program to evaluate changes in career interests; self-assessment of knowledge and skills was also completed following each simulation. Baseline and final evaluations were compared using the Wilcoxon Signed-Rank test. Results SEAD participants showed significant improvement in knowledge and confidence in surgical skills specific to OTOHNS. The greatest knowledge gain was in ear examination, and greatest gain in confidence was in draining peritonsillar abscesses. The OTOHNS session received a mean rating of 4.8 on a 5-point scale and was the most popular surgical specialty participating in the program. Eight of the 18 participants were interested in OTOHNS as a career at baseline; over the course of the program, two students gained interest and two lost interest in OTOHNS as a potential career path, demonstrating the potential for helping students refine their career choice. Conclusions Participants were able to develop OTOHNS knowledge and surgical skills as well as refine their perspective on OTOHNS as a potential career option. These findings demonstrate the potential benefits of OTOHNS departments/divisions implementing observerships, simulations, and career information sessions in pre-clerkship medical education, either in the context of SEAD or as an independent initiative

Pseudomonas aeruginosa in swimming pools

Swimming pools, can pose a public health risk to users due to their bacterial contamination especially if they were drug resistant. This study aimed to assess the bacteriological quality and the occurrence and antimicrobial resistance of Pseudomonas aeruginosa in swimming pools. Approximately two thirds (66.7%) of the examined pool water samples in this study failed to meet the Egyptian standards of bacteriological indicators P. aeruginosa was found in 26 (21.7%) samples. Indoor pools showed higher isolation rates than outdoor pools (33.3 versus 16.7%, respectively). Isolation of P. aeruginosa was positively correlated with pH, HPC, TC, and Escherichia coli, while it was negatively correlated with chlorine. Nine (34.6%) P. aeruginosa isolates were multidrug resistant. The findings of this study indicate that P. aeruginosa strains in swimming pools can be multidrug resistant which creates a hazard especially for individuals at high risk for infections

Assessment of laparoscopic skills: Comparing the reliability of global rating and entrustability tools

Background: Competence by design (CBD) residency programs increasingly depend on tools that provide reliable assessments, require minimal rater training, and measure progression through the CBD milestones. To assess intraoperative skills, global rating scales and entrustability ratings are commonly used but may require extensive training.  The Competency Continuum (CC) is a CBD framework that may be used as an assessment tool to assess laparoscopic skills. The study aimed to compare the CC to two other assessment tools: the Global Operative Assessment of Laparoscopic Skills (GOALS) and the Zwisch scale.Methods: Four expert surgeons rated thirty laparoscopic cholecystectomy videos. Two raters used the GOALS scale while the remaining two raters used both the Zwisch scale and CC. Each rater received scale-specific training. Descriptive statistics, inter-rater reliabilities (IRR), and Pearson’s correlations were calculated for each scale.Results: Significant positive correlations between GOALS and Zwisch (r = 0.75, p < 0.001), CC and GOALS (r = 0.79, p < 0.001), and CC and Zwisch (r = 0.90, p < 0.001) were found. The CC had an inter-rater reliability of 0.74 whereas the GOALS and Zwisch scales had inter-rater reliabilities of 0.44 and 0.43, respectively. Compared to GOALS and Zwisch scales, the CC had the highest inter-rater reliability and required minimal rater training to achieve reliable scores.Conclusion: The CC may be a reliable tool to assess intraoperative laparoscopic skills and provide trainees with formative feedback relevant to the CBD milestones. Further research should collect further validity evidence for the use of the CC as an independent assessment tool.Contexte : Les programmes de résidence structurés autour de la compétence par conception (CPC) dépendent de plus en plus d’outils qui fournissent des évaluations fiables, nécessitent une formation minimale des évaluateurs et mesurent la progression dans les étapes de la CPC. Pour évaluer les compétences peropératoires, les échelles d’évaluation globale et de confiance sont couramment utilisées mais peuvent nécessiter une formation approfondie. Le Continuum des compétences (CC) est un cadre de la CPC qui peut être utilisé comme outil d’évaluation des compétences laparoscopiques. L’étude visait à comparer le CC à deux autres outils d’évaluation : l’évaluation globale opératoire des compétences laparoscopiques (GOALS) et l’échelle de Zwisch.Méthodes : Quatre chirurgiens experts ont évalué trente vidéos de cholécystectomie laparoscopique. Deux évaluateurs ont utilisé l’échelle GOALS tandis que les deux autres ont utilisé l’échelle Zwisch et le CC. Chacun d’eux avait reçu une formation spécifique à l’échelle utilisée. Des statistiques descriptives, la fiabilité inter-évaluateurs (FIÉ) et des corrélations de Pearson ont été calculées pour chaque échelle.Résultats : Des corrélations positives significatives ont été trouvées entre les échelles GOALS et Zwisch (r=0.75, p<0.001), CC et GOALS (r=0.79, p<0.001), et CC et Zwisch (r=0.90, p<0.001). Le CC avait une fiabilité inter-évaluateurs de 0,74 tandis que les échelles GOALS et Zwisch avaient des fiabilités inter-évaluateurs de 0,44 et 0,43, respectivement. Par rapport aux échelles GOALS et Zwisch, le CC avait la fiabilité inter-évaluateurs la plus élevée et ne nécessitait qu’une formation minimale des évaluateurs pour obtenir des scores fiables.Conclusion : Le CC constituerait un outil fiable pour évaluer les compétences laparoscopiques peropératoires et pour fournir aux stagiaires une rétroaction formatrice pertinente pour les étapes de la CPC. Des recherches supplémentaires devraient être entreprises pour recueillir plus de preuves de validité pour l’utilisation du CC comme outil d’évaluation indépendant

A chance for reform: The environmental impact of travel for general surgery residency interviews

Background: In light of the global climate emergency, it is worth reconsidering the current practice of medical students traveling to interview for residency positions. We sought to estimate carbon dioxide (CO2) emissions associated with travel for general surgery residency interviews in Canada, and the potential avoided emissions if interviews were restructured.Methods: An 8-item survey was constructed to collect data on cities visited, travel modalities, and costs incurred. Applicants to the University of Ottawa General Surgery Program during the 2019/20 Canadian Resident Matching Service (CaRMS) cycle were invited to complete the survey.  Potential reductions in CO2 emissions were modeled using a regionalized interview process with either one or two cities.Results: Of a total of 56 applicants, 39 (70%) completed the survey. Applicants on average visited 10 cities with a mean total cost of $4,866 (95% CI=3,995-5,737) per applicant. Mean CO2 emissions were 1.82 (95% CI=1.50-2.14) tonnes per applicant, and the total CO2 emissions by applicants was estimated to be 101.9 (95% CI=84.0 – 119.8) tonnes. In models wherein interviews are regionalized to one or two cities, emissions would be 57.9 tonnes (43.2% reduction) and 84.2 tonnes (17.4% reduction), respectively. Overall, 74.4% of respondents were concerned about the environmental impact of travel and 46% would prefer to interview by videoconference.Conclusion: Travel for general surgery residency interviews in Canada is associated with a considerable environmental impact. These findings are likely generalizable to other residency programs. Given the global climate crisis, the CaRMS application process must consider alternative structures.Contexte : Compte tenu de la situation d’urgence climatique mondiale, il convient de reconsidérer l’usage actuel selon lequel les étudiants en médecine se déplacent pour se présenter aux entrevues en vue d’obtenir un poste de résidence. Nous avons tenté d’estimer les émissions de dioxyde de carbone (CO2) causées par les déplacements pour les entretiens de résidence en chirurgie générale au Canada, et les émissions potentielles évitées si les entretiens étaient organisés autrement.Méthodes : Un sondage comportant huit questions a été élaboré pour recueillir les données sur les villes visitées, les modalités de voyage et les coûts encourus. Les candidats au programme de chirurgie générale de l’Université d’Ottawa au cours du cycle 2019/20 du Service canadien de jumelage des résidents (CaRMS) ont été invités à y répondre. Les réductions potentielles des émissions de CO2 ont été modélisées à l’aide d’un processus d’entrevue régionalisé avec une ou deux villes.Résultats : Sur un total de 56 candidats, 39 (70 %) ont répondu au sondage. Les candidats ont visité en moyenne 10 villes, pour un coût total moyen de 4 866 dollars (IC 95 % = 3 995-5 737) par candidat. Les émissions moyennes de CO2 étaient de 1,82 (IC 95 % = 1,50-2,14) tonne par candidat, et le total des émissions de CO2 pour l’ensemble des candidats était estimé à 101,9 (IC 95 % = 84,0 - 119,8) tonnes. D’après les modèles où les entrevues sont régionalisées avec une ou deux villes, les émissions seraient respectivement de 57,9 tonnes (43,2 % de réduction) et 84,2 tonnes (17,4 % de réduction). Dans l’ensemble, 74,4 % des personnes interrogées se disent préoccupées par l’impact environnemental des déplacements et 46 % préféreraient que l’entretien se fasse par vidéoconférence.Conclusion : Les déplacements pour les entrevues de résidence en chirurgie générale au Canada ont un impact environnemental considérable. Ces conclusions sont probablement généralisables à d’autres programmes de résidence. Compte tenu de la crise climatique mondiale, il conviendrait d’envisager d’autres modalités d’organisation des entrevues pour le processus de candidatures du CaRMS

Use of bilateral internal thoracic artery during coronary artery bypass graft surgery in Canada: The bilateral internal thoracic artery survey.

The internal thoracic artery is the gold standard conduit in coronary artery bypass grafting. Although the right and left internal thoracic arteries are excellent conduits, the use of the bilateral internal thoracic artery is not widespread. A recent report of the Society of Thoracic Surgery revealed that only a small percentage of patients receive a bilateral internal thoracic artery in North America. The aim of this study was to determine the current use of the bilateral internal thoracic artery during coronary artery bypass grafting among cardiac surgeons in Canada and identify the main concerns that limit the use of these conduits. We developed an online survey with 17 questions about the use of the bilateral internal thoracic artery in different clinical scenarios. An invitation to participate was sent to all the adult cardiac surgeons currently in practice in Canada. A total of 101 surgeons (69%) of 147 currently in practice across 27 different hospitals completed the survey. Forty percent of surgeons use the bilateral internal thoracic artery only sometimes (6%-25% of cases), 37% of surgeons use the bilateral internal thoracic artery very infrequently (50%). The most common concerns in the use of the bilateral internal thoracic artery are the risk of sternal wound infection and the unknown superiority of the right internal thoracic artery over other conduits. The majority of Canadian cardiac surgeons consider few clinical features, such as insulin-dependent diabetes mellitus or morbid obesity, as contraindications to the use of bilateral internal thoracic artery. However, the reported use of the bilateral internal thoracic artery is low. A wider diffusion of this technique is warranted to improve the results of coronary surgery