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Operative difficulty grading scale for laparoscopic cholecystectomy at a tertiary care hospital in Eastern Nepal

Background: Predictions of difficult cholecystectomy preoperative make the surgeon prepared, thereby making a more careful dissection, back up from senior surgeons, and a low threshold for early conversion. Objectives: To utilise an operative grading scale to predict open conversion, duration of surgery, total length of stay, complications and to validate Nassar score. Method: This was a prospective cross-sectional study done from 2020 July 9 to 2021 January 30 after ethical clearance among all patients of BPKIHS planned for laparoscopic cholecystectomy for symptomatic gallstone disease. Nassar scale was used for risk evaluation of difficult cholecystectomy. The intraoperative outcome parameters were bleeding, bile spillage, stone spillage, presence of bowel or biliary injury, operative time and conversion to open surgery. Postoperative outcomes noted were total length of stay, 30-day complications, reintervention, and mortality. The data were entered in Microsoft Excel sheet 2010 and analysis was done in SPSS v.26. Results: Seventy-four patients were analysed. Comparison of Nassar scoring system with outcomes revealed a significant association of rising Nassar grade with bile spillage, stone spillage, bleeding, post-surgical drain placement, conversion to open, duration of surgery, and total length of stay. Operative time was significantly more in male, cholecystitis, and interval cholecystectomy. Conversion to open was significantly associated with Nassar grade 4, acute cholecystitis, and interval cholecystectomy. There was no mortality, 30-day reintervention, and complication. Conclusion: Nassar operating scale is simple scale that can be used by all level of surgeons to predict difficult laparoscopic cholecystectomy. Rising grades have significant correlation with difficulty and complications.

Nassar grading system is simplified tool including gall bladder appearance, cystic pedicle, and adhesion and categories into four grades. 5 This study was conducted with the aim of utilising an operative grading scale to predict open conversion, duration of surgery, total length of stay, and complications as well as to validate the Nassar score.

METHODOLOGY
This was a prospective cross-sectional study done in the department of surgery in B. P. Koirala Institute of Health Science (BPKIHS), Dharan, Sunsari, Nepal from 9 th July 2020 to 30 th January 2021. All patients planned for laparoscopic cholecystectomy for symptomatic gallstone disease were included after obtaining duly signed informed consent. For evaluation of the risk of difficult cholecystectomy, the Nassar scale was used. 6 The Nassar Grading Scale includes gall bladder appearance, cystic pedicle, and associated adhesions. Based upon these criteria, difficulty levels were graded in the four grades (Table 1). Grade five was Mirizzi type two or higher, cholecysto-cutaneous, cholecysto-duodenal or cholecysto-colic fistula which was included in type four.
Laparoscopic cholecystectomy was done using the standard four-port technique. Intraoperative findings with special attention to gall bladder appearance, cystic pedicle, and associated adhesions were noted . The   decision of conversion to open surgery was made if  excessive bleeding occurred, difficult to identify cystic  duct and cystic artery due to frozen Calot's triangle, time  to identify cystic duct and artery more than 60 minutes,  associated bile duct and bowel injury were  Bleeding was defined as vascular injury, slippage of clips/ ligatures of the cystic artery, and liver bed bleeding.
Operative time was the duration of surgery from opening the first umbilical port to the closure of the port with a skin stapler. Drains were kept if significant biliary and/or vascular injury or bleeding (>100 mL), empyema, mucocoele, and acute cholecystitis. The discharge criteria were able to tolerate an oral diet, mobilise safely, hemodynamically stable without significant pain, nausea, and/or vomiting.
Patients were discharged after 24 hours if vital stable and patient taken orally on the first post-operative day. If the drain was kept, the patient was discharged only after the drain output was less than 50 min and the serosanguinous content. If associated bowel injury or bile duct injury was present, it was managed accordingly with the help of a senior consultant surgeon. All patients were asked to follow up with Surgery Outpatient Department physically after one week and four weeks.
Since histopathology report was also given after four weeks, it was easy to do follow-up of the patients as well as reviewing the histopathology report. Any complications, 30-day reintervention, morbidity, and mortality were noted.
In this study, sample size was estimated considering 95% confidence interval and 80% power to estimate sample size. In this regard, the authors used Nassar grading scale to identify the complication by grading wise. The Welch's one-way ANOVA was used to evaluate the relationship of the Nassar scale with the continuous outcomes of duration of surgery. Receiver operating characteristic (ROC) curve analysis was done using cut off value of duration of surgery >90 minutes and total length of stay more than two days.
Patients were categorised as Nassar grade one in 51 (68.9%) patients, grade two in 9 (12.2%) patients, grade three in 9 (12.2%) patients, and grade four in 5 (6.8%) patients (Table 1). There were two (3.2%) cases of Nassar grade four, and 5 (8.1%) cases of Nassar grade three in biliary colic patients but there were three (60%) cases of Nassar grade one in biliary pancreatitis (Table 3). Bile spillage, stone spillage, and bleeding were present in 20 (27%) patients, 11 (14.9%) patients, and 21 ( 28.4%) patients respectively (Table 2). Post-surgical drain placement and conversion to open were present in 11 (14.9%) patients and one (1.4%) patient respectively. There was no biliary leakage present in the drain in any of the patients. The drain was removed once the drain output was less than 50 ml and serosanguinous in content. The laparoscopic procedure was converted to open in one (1.4%) patient. The reasons for conversion were frozen Calot's triangle in which it was difficult to proceed laparoscopically. All 74 (100%) patients, had good recovery. There was no mortality.
The comparison of various grades of Nassar scoring system with the perioperative outcomes revealed a significant association of rising Nassar grade with bile spillage (p-value = 0.012), stone spillage (p-value = 0.003), bleeding (p-value <0.001), post-surgical drain placement (p-value <0.001), conversion to open (p-value = 0.003) and duration of surgery (p-value = 0.001) ( Table  4). There was a significant association of rising Nassar grade with total length of stay (p-value = 0.001) ( Table  4). The operative time was significantly more in male patients (p-value = 0.001), cholecystitis patients (p-value <0.001), and interval cholecystectomy admitted after six weeks (p-value = 0.024) ( Table 5). Conversion to open was significantly associated with Nassar grade four (p-value = 0.003), acute cholecystitis (p-value = 0.008), and interval cholecystectomy admitted after six weeks (p-value = 0.01) ( Table 6).
In ROC curve analysis, the association of Nassar grade with surgical variables and patient outcome were calculated. Operative time of more than 90 minutes and a post-operative hospital stay of more than two days were taken as cut off values. The analysis showed a strong association of rising Nassar grade with operative time (AUROC = 0.877), post-surgical drain placement (AUROC = 0.895), conversion to open (AUROC = 0.973) and postoperative hospital stay more than two days (AUROC = 0.959) ( Table 7). ROC curve areas are mentioned in

DISCUSSION
This study is a prospective validation of Nassar grade. The primary outcome of this study was "conversion to open" which correlates with the rise in Nassar grades. There was one case in which conversion to open was done. None of the cases were undergone reintervention.
The definition of difficult laparoscopic cholecystectomy is not well established because the difficulty depends not only on patient factors but also on surgeon's expertise. 1 Significant prolongation of surgery acts as a predictor for difficult laparoscopic cholecystectomy. 6,7 There are various studies that define preoperative factors as a predictor for difficult laparoscopic cholecystectomy. [8][9][10] Ghadhban labelled laparoscopic cholecystectomy difficult or easy based on history, age, prior admission for cholecystitis, body mass index, abdominal scar, palpable gall bladder, radiologically gall bladder wall thickness, pericholecystic collection, and impacted stone. 11 Sugrue et al. developed a new scoring system for difficult laparoscopic cholecystectomy based on intraoperative findings such as gall bladder appearance, distension/ contraction, access, severe sepsis/complication, and time to identify cystic duct and artery more than 90 minutes. 8 Similarly, Sudhir and Raj labelled difficult laparoscopic cholecystectomy based on preoperative and intraoperative factors. 6

Figure 7: Total length of Stay (cut off >2 day)
Nassar grading is a well-designed scale based upon a large-scale multi-centric study for the evaluation of difficult laparoscopic cholecystectomy. It has four points based upon gall bladder appearance, cystic pedicle, and associated adhesions. The disadvantage of the study was that it only included intraoperative parameters to define difficult laparoscopic cholecystectomy does not include preoperative parameters. Present study had a conversion rate of 1.4%. The cause of conversion was the inability to identify the cystic duct and arteries due to frozen Calot's triangle. Although the study population was low, other studies also have conversion rates of 2.6% 9 to 12%. 10 The causes of conversion in the other studies were the inability to identify the anatomy of Calot's triangle as a result of inflammation in the gall bladder, dense adhesion of the gall bladder to the duodenum or CBD, and contracted gall bladder with shortening of cystic duct. 9,10 The latest Tokyo consensus underlines that conversion to open is neither failure nor complication and is actually for patient safety and same should be explained before surgery to patients.
Although in current case, majority of the bulk of patients were of biliary colic but among them 11.3% had a difficult laparoscopic cholecystectomy (Nassar grade three and four). In these conditions, the grading system may prove to be useful especially for junior surgeons. Other studies also have shown that 3.2% to 16% of patients with no preoperative predictors of difficult cholecystectomy had difficult laparoscopic cholecystectomy. 7,11 In this study, the operative time of >90 minutes were significantly associated with higher Nassar grade. Lal et al. stated that any laparoscopic cholecystectomy requiring more than 90 minutes was regarded as difficult. 12 Ghadhban labelled laparoscopic cholecystectomy difficult if the duration of surgery more than 60 minutes. 11 It was difficult to perform laparoscopic cholecystectomy in patients admitted on delayed admission because those patients admitted on a delay basis was previously admitted for acute cholecystitis and acute biliary pancreatitis. In this study, duration of surgery >90 minutes, total length of stay more than two days, bile spillage, stone spillage, and bleeding were significantly associated with Nassar scale except conversion to open (Table 4). Nassar scale can detect all predictors except conversion to open. So Nassar can validate to find out the intraoperative and post-operative outcomes.
Although these events did not lead to any post-operative complications or reinterventions in follow-ups, the results of this study may help junior surgeons to anticipate the difficulty in the early period, make a proper operative plan, and take early help.
The limitation of the study was its small sample size, single centre study, and only including perioperative factors to define difficult laparoscopic cholecystectomy. However, this study was a prospective study. The applicability of this study helps junior residents to define difficult laparoscopic cholecystectomy on the basis of Nassar scale and plan accordingly.

CONCLUSION
The Nassar operating scale is a simple scale and can be used by all level of surgeons to predict difficult laparoscopic cholecystectomy. The rising grade has significant correlation with conversion to open and increased duration of surgery. Although this is a study with limited samples, the applicability, consistency, and repeatability of the grading method were established. This shows its usefulness in as a method for reporting illness and intraoperative severity that may be used to change outcomes. A larger study may help for further validation of the Nassar grading scale.