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.

Discussion

There is recognised variability in polypectomy techniques.12–18 It is assumed that the choice of technique used for the removal of a particular polyp is determined by the polyp’s characteristics, that is, size, morphology, site and access (eg, endoscopic mucosal resection for a flat, 2 cm, right-sided polyp). These polyp-dependent variables influence the difficulty of a polypectomy procedure. However, polypectomy is also dependent on factors other than polyp characteristics, such as the endoscopist’s technical ability, scope stability, patient characteristics and the wider endoscopy team. Recent work has explored the assessment of polypectomy skills in more detail.19 The purpose of this study was to define and devise an easily reproducible scoring system that quantifies polyp characteristics and therefore links them to polypectomy levels of difficulty, which may inform training and competency assessment.

The Munich Polypectomy Study4 analysed 4000 snare polypectomies across 13 institutions and performed multivariate regression analysis to determine risk factors for polyp-related complications. The study results demonstrated that polyp size and right-sided location were associated with a higher complication rate. The authors concluded that polyps larger than 1 cm in the right colon or 2 cm in the left colon carried an increased risk of complications. Applying these cut-offs to this study, using our scoring system, right-sided lesions greater than 1 cm in size or left-sided lesions greater than 2 cm in size would score a minimum of 8 points. According to the Munich study, anything above this cut-off would qualify as high risk. Similarly, any polyp that scores above 8 points in this study would be deemed a relatively difficult (difficulty level III) polyp. It is expected that the majority of BCS colonoscopists should be able to manage level III polyps competently because of the high frequency of finding these lesions. If they did not have this level of competency then they would either be removing lesions they should not attempt, or too frequently referring on to another operator resulting in additional procedures.

The assigning of scores to polyps, and creation of levels, may help endoscopists decide when not to attempt to remove a particularly challenging polyp. The aim of this work is not to discourage endoscopists operating at a particular level to attempt more complex polypectomy, but to highlight the increased risks of such lesions. This may help to streamline endoscopic referral services and reduce complications.

The scoring system and polyp levels were validated by two specialist endoscopists. This could possibly have skewed the scoring towards an expert level of ability. As an example, both experts assigned a 3 cm sessile, left-sided polyp with easy access (giving a score of 11), to level III. However, it is acknowledged that not all colonoscopists would be able to manage a lesion of this size and morphology competently. Whether or not a particular endoscopist opts to perform polypectomy on this type of lesion may depend on other individual or situation-specific factors, such as experience, technical ability, the competence of the supporting team and the availability of equipment. The scoring system may then serve as a guide alongside the above-mentioned factors. It is acknowledged that it is not applicable under all circumstances for all endoscopists, but may help define standards for each level. Furthermore, large-scale, prospective validation by a wider range of endoscopists is required to strengthen the reliability of this scoring system.

There was a high degree of interrater agreement among the two expert endoscopists with regard to polyp scores as well as overall polyp levels. This demonstrates that the experts generally agreed on the expected level of competency required for each polypectomy difficulty ‘level’. The experts agreed on the classification of level I and II polyps; however, for the more difficult lesions, there was disagreement in two cases, which were rated as level III by expert 1 and level IV by expert 2. This variation in assigning levels may be explained by differences in the experts’ individual experience or approach to polypectomy. However, it highlights the fact that individual judgement should be used in conjunction with the polyp level on a case to case basis. The assignment of polypectomy levels may have an application for endoscopists operating at different levels of training, for example, all endoscopists performing flexible sigmoidoscopy should be able to remove level I polyps safely, whereas a BCS endoscopist may be expected to remove a level III polyp competently, exercising judgement as to whether a level IV polyp might need referral to a tertiary centre. This would require a detailed discussion among the endoscopic community.

The high interrater agreement for the scores assigned to each polyp illustrates that the scoring system is feasible and reproducible, and may help target training and assessment of polypectomy skills at different levels. However, we acknowledge that the two UK-based endoscopy experts in this study remain a highly selected group, which may have skewed their perception of what constitutes a difficult polypectomy. Further validation of this tool with a wider range of national and international endoscopists would enhance its applicability.

This study is the first to report a simple scoring system to determine the difficulty level of a polyp. It defines and quantifies easily measurable characteristics that determine the difficulty of a particular polypectomy. This, in turn, may help to stratify polypectomy ‘service levels’ and allocate resources to reflect the four levels of difficulty. Advanced, complex, or large sessile lesions generally require subspecialty endoscopic management to achieve complete and safe excision. They may require advanced endoscopic skills, specialised equipment, extra procedural time and a more experienced supporting team. They should thus be managed by specialists with the relevant expertise in the right environment. The choice between a surgical or endoscopic approach may depend on local expertise but the development of a network of specialist endoscopic teams may enable a wider choice for patients. A large Australian study20 has shown that when difficult or advanced lesions are managed by a tertiary endoscopic service, substantial cost savings can be realised with limited morbidity and no mortality when compared with surgery. Validation of the scoring system and polyp levels on a wider scale, and comparison with outcome data, may increase awareness in the endoscopic community and ultimately help improve polypectomy outcomes.

Key messages

·         What is already known on this topic

·         There are recognised differences in the difficulty level of polypectomy, based on polyp characteristics.

·         What this study adds

·         This is the first study which attempts to quantify the difficulty of polypectomy, using polyp characteristics.

·         Impact on clinical practice

·         The SMSA scoring system has wide utility for endoscopists and may help to stratify difficulty levels of polypectomy.

Source: BMJ