Laparoscopic cholecystectomy (LC) has replaced open cholecystectomy as the standard operation for symptomatic gallstone disease since the first procedure was performed by Mühe in 1985 [1] and popularised by subsequent pioneers [2]. Within a decade it was adopted worldwide because of smaller incisions, less postoperative pain, shorter hospital stay and early return to normal activity [3]. Gallstone disease is common, affecting an estimated 10–15% of adults in Western populations [4,5]; population-based data from the Gangetic belt of north India show a substantial burden that is higher among women and increases with age [6]. As a result, LC is now among the most frequently performed abdominal operations in tertiary care hospitals [7]. Although most LCs are uneventful, a significant minority are technically demanding because of dense adhesions, a thick-walled, fibrotic or contracted gallbladder, an impacted stone in Hartmann’s pouch, or an obscured Calot’s triangle. Such difficulty prolongs operative time, increases the likelihood of conversion to open surgery—reported between roughly 2% and 15% in various series [8–10]—and predisposes to bile duct injury, which remains the most feared complication of the operation [11]. Safe practice depends on obtaining the critical view of safety [12], and when this cannot be achieved the surgeon must resort to bail-out strategies such as subtotal cholecystectomy or conversion [13]. Predicting difficulty before surgery has several practical advantages: patients can be counselled realistically and consent can be tailored, the case can be allotted to an experienced surgeon, theatre time and equipment can be planned, and trainees can be selected appropriately. Many studies have identified preoperative risk factors for difficulty or conversion, including advanced age, male sex, obesity, previous abdominal surgery, previous acute cholecystitis, palpable gallbladder, leucocytosis, thickened gallbladder wall and impacted stone [14–20]. Several scoring systems have been proposed, including those developed in India [21–24] and in Europe [25,26]. Earlier Indian experience also highlighted the predictors of conversion and of difficult dissection [27–31]. However, the performance of these tools varies between populations. Differences in body habitus, disease pattern, referral practices and the tendency of patients in tertiary centres to present late with recurrent attacks may limit transferability. Standardised intraoperative grading scales [32,33] now provide an objective yardstick of difficulty that can serve as the reference outcome in preoperative prediction studies. We therefore undertook this study to assess the preoperative clinical, laboratory and ultrasonographic factors associated with difficult LC in a tertiary care hospital and to derive a simple scoring system. Aim and objectives To determine the proportion of difficult laparoscopic cholecystectomies in a tertiary care hospital. To evaluate the association of preoperative clinical, laboratory and ultrasonographic parameters with difficult LC. To identify independent predictors and to develop and assess a preoperative scoring system. To compare operative and postoperative outcomes between difficult and easy LC.

Study design and setting This was a hospital-based prospective observational study conducted in the Department of General Surgery of a tertiary care teaching hospital in India from January 2024 to December 2024. The study is reported in accordance with the STROBE statement [34]. Approval was obtained from the Institutional Ethics Committee and written informed consent was obtained from every participant. Sample size Assuming that about 25% of laparoscopic cholecystectomies are difficult, with a 95% confidence level and an absolute precision of 6%, the required sample size was calculated as n = Z²pq/d² = (1.96)² × 0.25 × 0.75 / (0.06)² ≈ 200. Consecutive eligible patients were enrolled until this number was reached. Selection criteria Inclusion criteria: adults aged 18 years or above with symptomatic cholelithiasis or chronic calculous cholecystitis, scheduled for elective LC, who gave consent. Exclusion criteria: (i) suspected or proven choledocholithiasis or previous ERCP; (ii) acute gallstone pancreatitis; (iii) acute cholecystitis diagnosed by the Tokyo Guidelines 2018 criteria [35] and operated on as an emergency (patients with a previous, resolved episode were included); (iv) suspected gallbladder malignancy; (v) pregnancy; (vi) ASA grade IV or above; and (vii) refusal of consent. During the study period 232 patients were assessed, 32 were excluded (choledocholithiasis/ERCP 11, refusal 7, acute pancreatitis 5, suspected malignancy 4, ASA IV 4, pregnancy 1) and 200 were enrolled. Preoperative assessment All patients underwent a standardised evaluation: demographic details, history (duration of symptoms, number of attacks, previous hospital admission for acute cholecystitis, previous abdominal surgery), comorbidities, anthropometry and abdominal examination (palpable gallbladder, Murphy’s sign, abdominal scars). Body mass index (BMI) was classified using WHO Asia-Pacific cut-offs, with ≥27.5 kg/m² taken as high risk [36]. Laboratory investigations included total leucocyte count (TLC) and liver function tests. Ultrasonography of the abdomen was done by a radiologist with more than five years of experience who was unaware of the study hypothesis. Operational definitions of the variables are given in Table 1. Table 1: Operational definitions of preoperative variables studied Variable Variable Definition / cut-off used Age Categorised as ≤40, 41–60 and >60 years Body mass index ≥27.5 kg/m² (WHO Asia-Pacific high-risk category) Previous upper abdominal surgery Any previous laparotomy or laparoscopy above the umbilicus, with a scar Previous acute cholecystitis ≥1 hospital admission for an acute attack of cholecystitis or biliary colic with fever/tenderness Long-standing symptoms Duration of symptoms >2 years Palpable gallbladder Gallbladder lump felt in the right hypochondrium Murphy’s sign Positive inspiratory arrest on palpation of the right subcostal area Leucocytosis TLC >11,000/mm³ Deranged liver function Any of: bilirubin >1.2 mg/dL, AST/ALT >40 IU/L, ALP >120 IU/L Thick-walled gallbladder Ultrasonographic wall thickness ≥4 mm Contracted gallbladder Shrunken gallbladder with little or no lumen and stone-filled Pericholecystic fluid Fluid collection around the gallbladder on ultrasonography Impacted stone Stone impacted in the neck/Hartmann’s pouch on ultrasonography Dilated common bile duct Diameter >6 mm on ultrasonography Operative technique All procedures were performed under general anaesthesia by the standard four-port technique with pneumoperitoneum maintained at 12–14 mmHg. Dissection of Calot’s triangle aimed at achieving the critical view of safety before clipping and dividing the cystic duct and artery. Operations were performed by consultant surgeons or by senior residents under direct supervision. Conversion was undertaken when the anatomy could not be defined safely, in case of uncontrolled bleeding or suspected bile duct injury, at the discretion of the operating surgeon. Intraoperative findings were recorded by an observer who was not aware of the preoperative predictor data. Definition of difficult laparoscopic cholecystectomy A laparoscopic cholecystectomy was labelled difficult if any one of the following was present: (a) operative time >90 minutes (skin incision to closure); (b) conversion to open surgery; (c) bail-out subtotal cholecystectomy; or (d) an intraoperative gallbladder grade of 3 or more on the Sugrue scale [32,33], which grades findings from 1 (normal-looking gallbladder with no adhesions) to 5 (gangrenous or perforated gallbladder, or difficulty such that the gallbladder cannot be visualised or retrieved safely). All other cases were classified as easy. Postoperative outcomes Postoperative complications were recorded up to 30 days and graded with the Clavien–Dindo classification [37]. Hospital stay was counted from the day of surgery until discharge. Statistical analysis Data were entered in Microsoft Excel and analysed with SPSS version 26 (IBM Corp., Armonk, NY). Continuous variables are expressed as mean ± standard deviation and compared with the independent-samples t-test; categorical variables are expressed as numbers and percentages and compared with the chi-square or Fisher exact test as appropriate. Odds ratios (OR) with 95% confidence intervals (CI) were calculated. Variables with p <0.05 on univariate analysis were entered into a multivariable logistic regression model (backward conditional method). Model fit was assessed with the Hosmer–Lemeshow test and Nagelkerke R². Each retained predictor was assigned points by dividing its regression coefficient by 0.6 and rounding to the nearest whole number. The discriminative ability of the score was assessed by ROC analysis, and sensitivity, specificity and predictive values were calculated at each cut-off. A p value <0.05 was considered statistically significant.

Study population Of the 200 patients, 56 (28.0%) had a difficult LC and 144 (72.0%) had an easy LC. The mean age of the whole cohort was 46.7 ± 13.2 years and 132 (66.0%) were women. Patients in the difficult group were older, more often male and had a higher BMI (Table 2). The proportion of patients above 60 years was more than three times higher in the difficult group (32.1% vs 9.7%). Diabetes mellitus and hypertension were not significantly associated with difficulty. Table 2: Baseline demographic and clinical characteristics of the study population (N = 200) Characteristic Difficult LC (n = 56) Easy LC (n = 144) Total (N = 200) p value Age (years), mean ± SD 51.9 ± 12.4 44.7 ± 13.0 46.7 ± 13.2 <0.001 Age group (years) ≤40 9 (16.1) 54 (37.5) 63 (31.5) <0.001 41–60 29 (51.8) 76 (52.8) 105 (52.5) >60 18 (32.1) 14 (9.7) 32 (16.0) Sex Male 28 (50.0) 40 (27.8) 68 (34.0) 0.003 Female 28 (50.0) 104 (72.2) 132 (66.0) Anthropometry and comorbidity BMI (kg/m²), mean ± SD 27.9 ± 3.6 25.4 ± 3.4 26.1 ± 3.6 <0.001 BMI ≥27.5 kg/m² 30 (53.6) 36 (25.0) 66 (33.0) <0.001 Diabetes mellitus 17 (30.4) 28 (19.4) 45 (22.5) 0.097 Hypertension 20 (35.7) 40 (27.8) 60 (30.0) 0.271 Data are n (%) unless stated otherwise. SD, standard deviation; BMI, body mass index. Clinical history and examination A history of previous upper abdominal surgery, previous admission with acute cholecystitis and symptoms lasting more than two years were significantly more common in the difficult group. On examination, a palpable gallbladder was found in 14.3% of difficult cases against 2.1% of easy cases (OR 7.83), and a positive Murphy’s sign was also more frequent (Table 3). Table 3: Association of history and clinical examination findings with difficult LC Variable Difficult LC (n = 56) Easy LC (n = 144) Unadjusted OR (95% CI) p value Previous upper abdominal surgery 12 (21.4) 8 (5.6) 4.64 (1.78–12.07) <0.001 Previous acute cholecystitis (admission) 20 (35.7) 18 (12.5) 3.89 (1.86–8.12) <0.001 Duration of symptoms >2 years 24 (42.9) 36 (25.0) 2.25 (1.17–4.31) 0.013 Palpable gallbladder 8 (14.3) 3 (2.1) 7.83 (2.00–30.73) 0.002 Positive Murphy’s sign 22 (39.3) 21 (14.6) 3.79 (1.87–7.70) <0.001 Data are n (%). OR, odds ratio; CI, confidence interval. p value by chi-square test, or Fisher exact test when any expected count was <5. Laboratory and ultrasonographic findings Mean TLC was significantly higher in the difficult group and leucocytosis was present in 37.5% of difficult against 10.4% of easy cases. Deranged liver function was also more frequent. Ultrasonography showed the strongest associations: gallbladder wall thickness was greater in the difficult group (4.2 ± 1.6 mm vs 2.6 ± 1.0 mm, p <0.001), and a wall thickness of ≥4 mm carried an unadjusted odds ratio of 11.51. Contracted gallbladder, pericholecystic fluid and an impacted stone were significantly associated with difficulty, whereas a dilated common bile duct was not (Table 4; Figure 1). Table 4: Laboratory and ultrasonographic findings in difficult and easy LC Variable Difficult LC (n = 56) Easy LC (n = 144) Unadjusted OR (95% CI) p value TLC (/mm³), mean ± SD 10420 ± 3150 8160 ± 2480 — <0.001 TLC >11,000/mm³ 21 (37.5) 15 (10.4) 5.16 (2.41–11.04) <0.001 Deranged liver function 18 (32.1) 22 (15.3) 2.63 (1.28–5.40) 0.007 Gallbladder wall thickness (mm), mean ± SD 4.2 ± 1.6 2.6 ± 1.0 — <0.001 Wall thickness ≥4 mm 31 (55.4) 14 (9.7) 11.51 (5.37–24.68) <0.001 Contracted gallbladder 10 (17.9) 4 (2.8) 7.61 (2.28–25.43) <0.001 Pericholecystic fluid 9 (16.1) 3 (2.1) 9.00 (2.34–34.64) <0.001 Impacted stone in neck/Hartmann’s pouch 19 (33.9) 12 (8.3) 5.65 (2.51–12.69) <0.001 Dilated common bile duct (>6 mm) 8 (14.3) 9 (6.3) 2.50 (0.91–6.85) 0.089 Data are n (%) unless stated otherwise. TLC, total leucocyte count; p value for continuous variables by independent-samples t-test. Intraoperative findings and outcomes The mean operative time was 112.4 ± 24.6 minutes in the difficult group and 52.3 ± 14.8 minutes in the easy group (p <0.001). Among the 56 difficult cases, the defining criteria were operative time >90 minutes (49 cases), Sugrue grade ≥3 (47), conversion to open surgery (9) and bail-out subtotal cholecystectomy (7); more than one criterion could be present in the same patient. Conversion occurred in 9 patients (4.5% of all patients, 16.1% of difficult cases); the reasons were dense adhesions with a frozen Calot’s triangle (6), uncontrolled bleeding (2) and Mirizzi syndrome (1). Seven patients required subtotal cholecystectomy (four laparoscopic, three after conversion). There was no bile duct injury and no mortality. Details are given in Table 5. Table 5: Intraoperative findings in difficult and easy LC Parameter Difficult LC (n = 56) Easy LC (n = 144) p value Operative time (min), mean ± SD 112.4 ± 24.6 52.3 ± 14.8 <0.001 Sugrue intraoperative grade Grade 1 0 (0.0) 84 (58.3) <0.001 Grade 2 9 (16.1) 60 (41.7) Grade 3 28 (50.0) 0 (0.0) Grade 4 14 (25.0) 0 (0.0) Grade 5 5 (8.9) 0 (0.0) Other intraoperative findings Conversion to open surgery 9 (16.1) 0 (0.0) <0.001 Bail-out subtotal cholecystectomy 7 (12.5) 0 (0.0) <0.001 Bile/stone spillage 17 (30.4) 11 (7.6) <0.001 Drain placement 38 (67.9) 18 (12.5) <0.001 Data are n (%) unless stated otherwise. Sugrue grades: 1, normal-looking gallbladder; 5, most severe findings. Multivariable analysis Thirteen variables with p <0.05 on univariate analysis were entered into the logistic regression model. After backward elimination, nine variables remained as independent predictors of difficult LC (Table 6). Gallbladder wall thickness ≥4 mm was the strongest predictor (adjusted OR 8.1), followed by palpable gallbladder (5.9), leucocytosis (3.6) and previous upper abdominal surgery (3.4). Positive Murphy’s sign, long-standing symptoms, deranged liver function, contracted gallbladder (adjusted OR 3.1, 95% CI 0.7–14.2) and pericholecystic fluid (adjusted OR 4.2, 95% CI 0.7–25.3) lost significance and were removed. The model showed good calibration (Hosmer–Lemeshow p = 0.62) and explained about 52% of the variance (Nagelkerke R² = 0.52). Table 6: Multivariable logistic regression – independent predictors of difficult LC Predictor Adjusted OR (95% CI) p value Age >60 years 2.9 (1.2–7.1) 0.019 Male sex 2.4 (1.1–5.3) 0.030 BMI ≥27.5 kg/m² 2.7 (1.2–6.0) 0.016 Previous upper abdominal surgery 3.4 (1.1–10.5) 0.033 Previous acute cholecystitis 2.8 (1.1–7.1) 0.031 Palpable gallbladder 5.9 (1.2–29.0) 0.029 TLC >11,000/mm³ 3.6 (1.4–9.4) 0.008 Gallbladder wall thickness ≥4 mm 8.1 (3.2–20.6) <0.001 Impacted stone 3.3 (1.2–9.0) 0.020 Hosmer–Lemeshow p = 0.62; Nagelkerke R² = 0.52. OR, odds ratio; CI, confidence interval. Preoperative scoring system Points were assigned to the nine independent predictors from their regression coefficients, giving a score that ranges from 0 to 19 (Table 7). The mean score was 10.4 ± 3.3 in the difficult group and 4.7 ± 2.9 in the easy group (p <0.001). The area under the ROC curve was 0.88 (95% CI 0.83–0.93) (Figure 2). Performance at different cut-offs is shown in Table 8. A cut-off of ≥8 gave the best balance (Youden index 0.63), with a sensitivity of 78.6%, specificity of 84.0%, positive predictive value of 65.7% and negative predictive value of 91.0%. Table 7: Proposed preoperative scoring system for predicting difficult LC Predictor Points Gallbladder wall thickness ≥4 mm 3 Palpable gallbladder 3 Age >60 years 2 BMI ≥27.5 kg/m² 2 Previous upper abdominal surgery 2 Previous acute cholecystitis 2 TLC >11,000/mm³ 2 Impacted stone 2 Male sex 1 Maximum possible score 19 Table 8: Diagnostic performance of the score at different cut-offs Cut-off Sensitivity (%) Specificity (%) PPV (%) NPV (%) ≥6 92.9 61.1 48.1 95.7 ≥7 87.5 72.9 55.7 93.8 ≥8 78.6 84.0 65.7 91.0 ≥9 67.9 90.3 73.1 87.8 ≥10 55.4 95.1 81.6 84.6 PPV, positive predictive value; NPV, negative predictive value. Best cut-off: ≥8. When patients were divided into three risk categories, the probability of a difficult LC rose steeply with the score: 4.3% in the low-risk group (score ≤5), 19.5% in the intermediate group (6–7) and 65.7% in the high-risk group (≥8). Eight of the nine conversions occurred in the high-risk group and none in the low-risk group (Table 9). Table 9: Risk stratification by preoperative score Risk category (score) Patients (n) Difficult LC, n (%) Conversion, n (%) Low (0–5) 92 4 (4.3) 0 (0.0) Intermediate (6–7) 41 8 (19.5) 1 (2.4) High (≥8) 67 44 (65.7) 8 (11.9) Total 200 56 (28.0) 9 (4.5) Postoperative outcomes Postoperative complications occurred in 11 of 56 patients (19.6%) in the difficult group and 4 of 144 (2.8%) in the easy group (OR 8.56, p <0.001). All were Clavien–Dindo grade I–II except three bile leaks, which were managed with percutaneous drainage and endoscopic stenting (grade IIIa) and resolved. Mean hospital stay was 4.6 ± 2.1 days in the difficult group and 1.9 ± 0.8 days in the easy group (p <0.001) (Table 10). Table 10: Postoperative complications and hospital stay Outcome Difficult LC (n = 56) Easy LC (n = 144) Superficial surgical-site infection 5 2 Bile leak 3 0 Subhepatic collection 2 0 Prolonged ileus 1 0 Port-site haematoma 0 1 Urinary retention 0 1 Total complications, n (%) 11 (19.6) 4 (2.8) Hospital stay (days), mean ± SD 4.6 ± 2.1 1.9 ± 0.8 No bile duct injury, readmission or mortality occurred in the series.

Even with well-established technique, a considerable proportion of laparoscopic cholecystectomies present unexpected difficulty. In this prospective study from a tertiary care hospital, 28.0% of cases met our composite definition of difficult LC, and nine independent preoperative predictors—older age, male sex, higher BMI, previous upper abdominal surgery, previous acute cholecystitis, palpable gallbladder, leucocytosis, a thick-walled gallbladder and an impacted stone—were identified. A scoring system built from these variables discriminated difficult from easy cases with good accuracy (AUC 0.88). The proportion of difficult cases is of the same order as that reported in Indian series that used operative time and intraoperative findings to define difficulty [21,22,28], and our conversion rate of 4.5% lies within the range reported in large international series [8–10]. Patients over 60 years had nearly threefold higher adjusted odds of difficulty. Older patients tend to have long-standing disease with repeated subclinical inflammation, leading to fibrosis, dense adhesions and a contracted gallbladder, and they present later because of comorbidity. Age has been identified as a predictor of difficulty or conversion in several studies [14,16,18,21,23,27] and in a meta-analysis [20], and was a component of the Indian scoring systems of Randhawa and Pujahari [21] and Gupta et al. [23]. Male sex had an adjusted OR of 2.4. Men are reported to have more intense inflammation and fibrosis around the gallbladder and a less favourable operative field, and male sex was a risk factor in earlier Indian [21,23,30] and international [8,18,19] reports. The male predominance in our difficult group (50.0% vs 27.8%) is in keeping with this experience, though women formed two-thirds of the whole cohort, as expected in gallstone disease [6]. A BMI ≥27.5 kg/m² (the Asian high-risk cut-off [36]) increased the odds of difficulty 2.7-fold. Excess visceral and intra-abdominal fat in the hepatoduodenal ligament and the gallbladder fossa obscures anatomy, makes retraction harder and reduces working space. Obesity has been linked with longer operation and a greater need for conversion in Indian and other series [22,24,28,30], and the importance of using Asian-specific BMI categories rather than conventional ones is noteworthy for Indian patients [36]. Previous upper abdominal surgery produces adhesions between the omentum, duodenum, colon and gallbladder, hampering access and dissection. This was an independent predictor in our study (adjusted OR 3.4), in agreement with several authors [15,28,29]. Similarly, a previous admission with acute cholecystitis predicted difficulty (adjusted OR 2.8): an attack leaves oedema, adhesions and a fibrotic Calot’s triangle, as reported by Gupta et al. [23] and Vivek et al. [24], and by international investigators [17,19]. A palpable gallbladder indicates a distended organ—mucocele or empyema—or an inflammatory mass wrapped by omentum. It carried the second highest adjusted OR (5.9) in our model, although the wide confidence interval reflects the small number of such patients. Palpable gallbladder and similar clinical findings have also been used in Indian scoring systems [21,24,31], and clinicoradiological assessment has been advocated by Nidoni et al. [30]. Leucocytosis (adjusted OR 3.6) probably reflects ongoing or recent inflammation, which makes tissue planes oedematous and friable; this has been shown in other series [22,24,31]. By contrast, tenderness and deranged liver function did not remain independent predictors after adjustment, suggesting that their effect is mediated by the inflammatory markers already in the model. Ultrasonography contributed the strongest predictor. A gallbladder wall thickness of ≥4 mm was associated with an adjusted OR of 8.1, and was present in 55.4% of difficult cases. A thick wall signals chronic or acute-on-chronic inflammation and correlates with adherence to the liver bed, difficult grasping and a high likelihood of subtotal cholecystectomy. This finding agrees with the observations of Nachnani and Supe [22], Randhawa and Pujahari [21], Singh and Ohri [28] and Nidoni et al. [30], and with the European scores of Bourgouin et al. [25] and Sutcliffe et al. [26] and the meta-analysis of Rothman et al. [20]. An impacted stone in Hartmann’s pouch (adjusted OR 3.3) causes mucosal ulceration, oedema and distortion of the cystic duct, and made dissection of Calot’s triangle harder; related observations have been made in Indian studies [24,29]. Contracted gallbladder and pericholecystic fluid were significant on univariate analysis but not after adjustment, probably because of their low frequency and their overlap with wall thickening; larger studies may clarify their independent role. Diabetes mellitus, hypertension and a dilated common bile duct were not significantly associated with difficulty in our cohort. The role of diabetes has been inconsistent in the literature [17,19,20], and in an elective setting with well-controlled glycaemia its effect may be minimal. The nine-variable, 19-point score is simple, because every item can be obtained from history, examination, a total count and a routine ultrasound scan. A cut-off of ≥8 classified patients with a sensitivity of 78.6%, specificity of 84.0% and a negative predictive value of 91.0%; at a lower cut-off of ≥6, the sensitivity rose to 92.9% and the NPV to 95.7%, which could be useful for screening patients who should be allotted to less experienced surgeons. Importantly, the high-risk group (score ≥8) accounted for 8 of the 9 conversions, and none of the low-risk patients needed conversion. Our discriminative ability (AUC 0.88) is similar to or better than that reported for earlier scoring systems from India [21,23,24] and abroad [25,26], although direct comparison is limited by the different definitions of difficulty and the different variables included. We deliberately included only variables that are available before surgery in any Indian district or tertiary setting, without relying on imaging beyond ultrasonography. Outcomes and clinical implications Difficult LC was associated with a twofold or greater increase in operative time, much more frequent drain placement, a higher complication rate (19.6% vs 2.8%) and a more than doubled hospital stay. Although no bile duct injury occurred, three bile leaks were confined to the difficult group. Bile duct injury is known to be related to inflammation and distorted anatomy [11], so identification of high-risk patients before operation is an important safety measure. In patients with a high score we suggest that surgery be performed or directly supervised by an experienced surgeon, that the patient be counselled about the higher chance of conversion or subtotal cholecystectomy, that the critical view of safety be pursued strictly [12], and that bail-out options be considered early [13]. Pre-planning also helps tertiary centres in India to manage long waiting lists and training needs. Strengths and limitations Strengths of this study include its prospective design, standardised data collection, blinded ultrasonography and observer recording of intraoperative findings, and the use of an objective intraoperative grading scale [32,33] in the definition of difficulty. The limitations are: (i) single-centre design, which limits generalisability; (ii) the modest sample size and the relatively low events-per-variable ratio of the multivariable model, which may have produced wide confidence intervals (for example for palpable gallbladder) and may overestimate the performance of the score; (iii) the composite definition of difficulty, which includes operative time and is influenced by surgeon experience, which we did not analyse separately; (iv) exclusion of emergency acute cholecystitis, so the results apply only to elective surgery; and (v) the absence of external validation of the score. A multicentre validation cohort is needed before routine use.

Difficult laparoscopic cholecystectomy was seen in more than a quarter of patients in this tertiary care hospital series. Age above 60 years, male sex, BMI ≥27.5 kg/m², previous upper abdominal surgery, previous acute cholecystitis, a palpable gallbladder, leucocytosis, gallbladder wall thickness ≥4 mm and an impacted stone were independent preoperative predictors. A simple 19-point score based on these variables showed good discrimination (AUC 0.88), with a cut-off of ≥8 identifying patients at high risk of difficulty, conversion and complications. Use of such a score can improve preoperative counselling, case allocation and operative planning; multicentre external validation is recommended.

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