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Surg Endosc. 2019 Jan;33(1):110-121. doi: 10.1007/s00464-018-6281-2. Epub 2018 Jun 28.

Utilisation of an operative difficulty grading scale for laparoscopic cholecystectomy.

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Department of Upper Gastrointestinal Surgery, University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK.
Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK.
Institute of Translational Medicine, University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK.
Trent Oesophago-Gastric Unit, Nottingham University Hospitals NHS Trust, Nottingham, UK.
West Midlands Research Collaborative, Academic Department of Surgery, Birmingham University, Birmingham, UK.
Department of Surgery, Warwick Hospital, Lakin Rd, Warwick, UK.
Department of Surgery, University Hospital Monklands, Lanarkshire, Scotland, UK.
Department of Surgery, University Hospital Monklands, Lanarkshire, Scotland, UK.



A reliable system for grading operative difficulty of laparoscopic cholecystectomy would standardise description of findings and reporting of outcomes. The aim of this study was to validate a difficulty grading system (Nassar scale), testing its applicability and consistency in two large prospective datasets.


Patient and disease-related variables and 30-day outcomes were identified in two prospective cholecystectomy databases: the multi-centre prospective cohort of 8820 patients from the recent CholeS Study and the single-surgeon series containing 4089 patients. Operative data and patient outcomes were correlated with Nassar operative difficultly scale, using Kendall's tau for dichotomous variables, or Jonckheere-Terpstra tests for continuous variables. A ROC curve analysis was performed, to quantify the predictive accuracy of the scale for each outcome, with continuous outcomes dichotomised, prior to analysis.


A higher operative difficulty grade was consistently associated with worse outcomes for the patients in both the reference and CholeS cohorts. The median length of stay increased from 0 to 4 days, and the 30-day complication rate from 7.6 to 24.4% as the difficulty grade increased from 1 to 4/5 (both p < 0.001). In the CholeS cohort, a higher difficulty grade was found to be most strongly associated with conversion to open and 30-day mortality (AUROC = 0.903, 0.822, respectively). On multivariable analysis, the Nassar operative difficultly scale was found to be a significant independent predictor of operative duration, conversion to open surgery, 30-day complications and 30-day reintervention (all p < 0.001).


We have shown that an operative difficulty scale can standardise the description of operative findings by multiple grades of surgeons to facilitate audit, training assessment and research. It provides a tool for reporting operative findings, disease severity and technical difficulty and can be utilised in future research to reliably compare outcomes according to case mix and intra-operative difficulty.


Cholecystectomy; Difficulty grading; Laparoscopic; Operative difficulty; Surgery

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