Establishment and Application of a Grading Management Model for Laparoscopic Cholecystectomy

Introduction

Laparoscopic cholecystectomy (LC) has emerged as the preferred surgical approach for a range of benign gallbladder conditions, including acute and chronic cholecystitis, gallstones, gallbladder polyps, and gallbladder adenomyomatosis [1]. Nevertheless, LC has its limitations due to the constraints of laparoscopic instruments. Cases involving factors like severe adhesions in the Calot triangle, anatomical anomalies, significant gallbladder edema, Mirizzi syndrome, or insufficient surgeon experience can necessitate a conversion to open surgery [2,3]. Such conversions can give rise to a cascade of serious surgical complications, including biliary injuries, substantial bleeding, and damage to adjacent organs. These complications not only result in the wastage of valuable medical resources and escalated medical costs but also carry significant medicolegal implications. Extensive research has been conducted domestically and internationally to identify risk factors associated with LC [4–6]. These studies have highlighted factors such as male sex, advanced age, prior upper abdominal surgery, diabetes, elevated body temperature, increased total bilirubin levels, thickened gallbladder wall, dilated common bile duct, shrunken gallbladder, acute cholecystitis, and surgeon experience [7]. However, the availability of predictive scoring systems for high-risk LC patients, including those requiring conversion to open surgery and those susceptible to complications, remains limited [8,9]. Only a handful of studies have endeavored to develop mathematical models based on historical data, to predict the necessity of converting to open surgery [10,11]. These attempts have yielded varying outcomes with limited clinical applicability [12]. Furthermore, comprehensive data validation remains a challenge. Currently, there is a notable absence of an efficient and practical hierarchical management model tailored for LC procedures, both domestically and internationally.

This study seeks to fill this void by establishing a scoring system that can predict high-risk LC cases, encompassing both the need for conversion to open surgery and the risk of complications. Also, for the first time, combined with the surgical experience of surgeons, hierarchical management was conducted to reduce the risk of LC surgery. This system will be rigorously validated to provide a comprehensive assessment of surgical risk associated with LC cases. Additionally, this research aims to explore a specialized hierarchical management model for LC procedures, categorizing cases into different tiers based on the surgeon’s level of experience. This stratification approach aims to improve the success rate of LC surgeries and reduce complications. Preoperatively, this model can assist surgeons with varying levels of laparoscopic experience in selecting appropriate cases, thereby reducing the need for conversion to open surgery and associated complications. Furthermore, it can enhance doctor-patient communication by informing patients and their families about the complexity of LC surgery, the potential for conversion to open surgery, and the risk of complications. This proactive communication can help prevent postoperative medicolegal disputes. Intraoperatively, cases with higher risk scores can be promptly converted to open surgery, mitigating the potential complications arising from inadequate laparoscopic procedures. For hospitals equipped to accommodate it, day surgery for selected cases can also be considered as an option. Compared with the 2018 Tokyo Guidelines and the Nassar 2020 prediction model, this scoring system is simpler and more practical, integrating surgical experience scores for the first time [13,14].

Material and Methods

GENERAL INFORMATION:

We performed a retrospective analysis of clinical data from 9414 patients who underwent LC at 2 hospitals in Shanghai between June 2013 and June 2018. The sample was selected using a convenience sampling method. These patients were categorized into 2 groups: the LC group (9176 patients) and the group experiencing conversion to open surgery and complications (238 patients). The LC group included patients who underwent successful LC procedures, while the latter group included patients who underwent conversion to open surgery (168 patients; conversion rate: 1.78%) and patients who experienced complications (125 patients; incidence rate: 1.33%). Among the 168 patients that required conversion to open surgery, 55 patients (32.73%) had concurrent complications. These complications encompassed intra-abdominal bleeding (20 cases), residual gallstones in the bile duct (32 cases), bile duct injuries (30 cases), bile leakage (9 cases), severe subcutaneous emphysema (2 cases), gastrointestinal tract injuries (9 cases), abdominal infections (19 cases), abdominal wall incisional hernias (2 cases), and venous thrombosis (2 cases).

The above data were analyzed by single-factor analysis using the chi-square test to determine the factors affecting conversion to open surgery and complications. Subsequently, logistic multivariate regression analysis was performed on the identified risk factors, using a stepwise elimination approach for further screening. Coefficients from the likelihood function established for high-risk LC were assigned to the respective risk factors. After calculating scores for each LC case, differences in the actual rates of conversion to open surgery and complications were compared among various score groups. Sensitivity and specificity for predicting high-risk LC at different scores were calculated, and a receiver operating characteristic (ROC) curve was plotted. The area under the ROC curve (AUC) was computed to evaluate the system’s performance. A specific score was calculated as the threshold for high-risk LC, with the aim of achieving optimal sensitivity and specificity. Detailed statistics can be seen in Tables 1–4.

The prospective study was conducted from January 2019 to December 2021, involving a total of 835 patients with benign gallbladder conditions admitted to our institution. Patients were assessed based on the criteria outlined in Table 3, including body temperature ≥38.5°C, frequency of episodes ≥3, maximum gallbladder wall thickness ≥ 5 mm, impacted gallbladder neck stone, and common bile duct diameter ≥8 mm. Since open surgery is directly performed when the score exceeds 3 points, according to the scale, a critical value of 2 was selected as the basis for grouping, to validate the effectiveness of the scale. The patients were divided into an observation group (with a score >2) and control group (with a score ≤2) by using propensity score matching. Subsequently, using the method of variance analysis, we compared the rates of conversion to open surgery and postoperative complications, including bleeding, biliary injury, residual common bile duct stones, bile leakage, intra-abdominal infection, and gastrointestinal tract injury, between the 2 groups. For detailed statistics, please refer to Table 5.

The ethical approval was given by Renhe Hospital, Shanghai University, with judgement’s reference number KJ2018-17. Informed consent was obtained from all patients. The study was registered at the Chinese Clinical Trial Registry, with registration number ChiCTR2400080799.

The inclusion criterion was patients with diagnosis of benign gallbladder diseases scheduled for LC surgery, who were categorized into the observation group (score >2) and the control group (score ≤2).

The exclusion criteria were patients with severe cardiopulmonary disease or uncontrolled hypertension or severe diabetes, patients with liver cancer or other gastrointestinal tumors, and patients undergoing other operations at the same time.

The discharge criteria were as follows: patients exhibited unhindered mobility, normal body temperature, a normal white blood cell count, comfort after eating, unobstructed flatulence and bowel movement, and well-healed surgical incisions.

The post-discharge follow-up was as follows: within 24 to 48 h of discharge, attending physicians contacted patients via telephone to assess their condition and provide further guidance. Patients returned for a follow-up examination by the attending physician 1 to 2 weeks after surgery, to evaluate their prognosis and other conditions.

METHODS:

Patients were placed under general anesthesia and underwent either the 3-port or 4-port conventional LC approach. The Trendelenburg position was assumed, with the right side elevated and the head positioned lower than the feet, while maintaining CO2 pneumoperitoneum pressure at 9 to 12 mm Hg. Dissection of the gallbladder was performed using an electrosurgical knife or an ultrasonic dissector, ensuring adequate exposure of the cystic duct and cystic artery. The cystic artery was secured with Hemlock clips, followed by occlusion and transection of the cystic duct. Meticulous checks for bleeding and bile leakage were conducted. Subsequently, the gallbladder was excised, and drainage tubes were placed at the Winslow foramen in some cases, emerging from the sheath puncture site at the intersection of the right lower rib margin and the anterior axillary line. In cases in which laparoscopy proved insufficient due to various factors, conversion to open cholecystectomy was performed intraoperatively.

OBSERVATIONAL MEASURES:

Patient characteristics, including sex, age, body mass index (BMI), history of diabetes, prior upper abdominal surgery, body temperature, frequency and duration of acute cholecystitis episodes, total bilirubin levels, gallbladder cross-sectional area, maximum gallbladder wall thickness, impaction of gallbladder neck stones, common bile duct diameter, and surgeon experience, were quantified and subjected to statistical analysis.

STATISTICAL ANALYSIS:

Statistical analysis was conducted using SPSS Statistics 27.0 software. A significance level of P<0.05 was considered statistically significant. Retrospective analysis using chi-square tests was done to identify factors influencing the conversion to open surgery and complications in LC, converting continuous variables such as age and BMI into categorical variables for statistical analysis. Thereafter, logistic regression analysis was performed using the likelihood ratio test, based on the maximum partial likelihood estimates to ascertain these risk factors. Values were assigned to risk factors based on the respective pre-coefficients in the likelihood function established for high-risk LC events, including conversion to open surgery and complications. Sensitivity and specificity for predicting high-risk LC cases were calculated for various scores, and an ROC curve was constructed to evaluate the system’s performance. A score was determined as the threshold for high risk, optimizing both the sensitivity and specificity. Prospective studies use cohort studies.

Results

Comparison of the single-factor analysis between the 2 groups is shown in Table 1. In our retrospective case series of 9414 LC procedures, we encountered 168 cases that required conversion to open surgery, resulting in a conversion rate of 1.78%, slightly below the average. There was no statistical difference in sex ratio(P=0.554), age(P=0.076), BMI (P=1.000), history of diabetes (P=0.110), previous history of upper abdominal surgery (P=0.169), and the maximum cross-sectional area of the gallbladder being ≥5×10 cm or ≤3×4 cm (P=0.630) between the 2 groups. Both groups had statistically significant differences (P<0.05) in temperature, frequency of cholecystitis attacks, duration of acute cholecystitis attacks, total bilirubin, maximum thickness of gallbladder wall, cholecystolithic obstruction at the neck of the gallbladder, diameter of common bile duct, and surgeon experience.

Among the factors (body temperature, number of episodes, gallbladder wall thickness, impacted gallbladder neck stone, common bile duct diameter, surgeon’s experience) demonstrating noteworthy differences (P<0.05) between the LC group and the group with conversion to open surgery and complications, a stepwise logistic regression analysis was performed using the conditional parameter estimate likelihood ratio test. The final model included 6 factors (excluding the total bilirubin levels (P>0.05)). Model validation was conducted using the Omnibus test, yielding a chi-squared statistic value of χ2=677.137, with P<0.001, in addition to individual factor statistics (Table 2).

Based on the outcomes of the model mentioned above, the formula for assessing high risk in LC surgery was as follows: P=ey/(1+ey), where y=1.09 × (temperature ≥38.5°C) + 1.00×(number of episodes ≥3) + 1.77 × (maximum gallbladder wall thickness ≥5 mm) + 1.62×(gallbladder neck stone impaction) + 1.91×(common bile duct diameter ≥8 mm) + 1.26×(surgeon experience: 51–200 cases) + 2.34×(surgeon experience: ≤50 cases) - 6.80. Each variable was assigned a value of 1 if the corresponding condition was met, and 0 if not met. Based on clinical practice experience and to facilitate statistical calculation, the coefficients were fine-tuned and optimized, as shown in Table 3. The ROC curve for the above-mentioned model is depicted in Figure 1, with an AUC value of the ROC curve as 0.893 and a 95% confidence interval of 0.871–0.914. The Hosmer-Lemeshow test showed P=0.429; therefore, the model fitting effect was good. At the optimal threshold point (where the ROC curve was closest to the upper-left corner), the sensitivity and specificity were 0.795 and 0.849, respectively. The total score on the aforementioned scale corresponding to the optimal threshold was 3. Therefore, in practical application, if a patient’s total score based on the above scale evaluation exceeded 3, it indicated a high risk for LC surgery. In such cases, it is advisable for the surgeon, whether performing open surgery or LC, to proceed with caution. Timely conversion to open surgery, if necessary, is recommended by experienced physicians.

Through the segregation of objective factors and surgeon-related factors, we developed a hierarchical management scoring system for LC surgery, which is outlined in Table 4.

Following the implementation of the hierarchical management scoring system for LC surgery, our hospital treated 835 patients diagnosed with benign gallbladder diseases from January 2019 to December 2021. After thorough evaluation, these patients were divided into 2 categories: the observation group (scores >2) and the control group (scores ≤2). In the control group, 685 patients underwent LC surgery, resulting in 2 patients needing conversion to open surgery and 6 patients experiencing complications. Conversely, in the observation group, 15 patients underwent open cholecystectomy, while 135 patients underwent LC surgery. Among these, 3 patients required conversion to open surgery, and 5 patients faced complications. Notably, the control group exhibited significantly lower rates of conversion to open surgery and postoperative complications than did the observation group, with a statistically significant difference (P<0.05; Table 5). The results suggest that this LC surgical hierarchical grading and management scoring system is effective.

Discussion

LC has gained prominence as the preferred surgical approach for treating benign gallbladder diseases. However, the anatomical diversity of structures such as the cystic duct, cystic artery, and common bile duct, along with the complex and varied pathophysiological changes associated with gallbladder inflammation, continue to make LC surgery susceptible to conversion to open surgery and associated complications. In addition to patient-related factors, the surgeon’s experience and expertise can influence the surgical outcome. Opting for timely conversion when necessary is a prudent decision, effectively preventing additional harm and lowering the incidence of complications. While a conversion from LC to open surgery does not necessarily signify surgical failure and can reduce postoperative complications, it concurrently extends the duration of surgery and hospitalization, increases patient discomfort, and results in higher medical costs. Consequently, it is crucial to minimize both the conversion rate and complications associated with LC.

Existing reports suggest that the rate of conversion from LC to open surgery falls within the range of approximately 1.03% to 3.7% [15,16]. The specific reasons for conversion observed in this study encompassed several factors: (1) Substantial adhesions between the greater omentum, adjacent organs, and the gallbladder wall led to increased bleeding during laparoscopic dissection and compromised the visual field; (2) impacted gallstones in the gallbladder neck disrupted the anatomical arrangement of the gallbladder triangle, obscuring the relationship between its components; (3) scar tissue adhesions within the gallbladder triangle resulted in unclear anatomical boundaries, leading to bile duct injuries; (4) pronounced edema in the gallbladder triangle increased the fragility of the gallbladder artery, causing rupture and bleeding; (5) poorly defined demarcation between the gallbladder neck and cystic duct raised suspicion of Mirizzi syndrome or confirmed its presence; (6) incidental discovery of gallbladder carcinoma occurred; (7) intraoperative identification of common bile duct stones occurred; (8) severe inflammation of the gallbladder was combined with insufficient surgical experience, lack of confidence, and inadvertent injuries; and (9) factors such as advanced age and compromised general condition, associated with poor cardiopulmonary function and noticeable CO2 retention during surgery, led to extended surgical durations.

Our retrospective clinical data, analyzed through logistic regression, revealed that certain factors, including a body temperature of ≥38.5°C, the occurrence of acute gallbladder attacks ≥3 times, gallbladder wall thickness ≥5 mm, impaction of gallstones in the gallbladder neck, common bile duct diameter ≥8 mm, and surgeon experience of ≤200 cases, are significant risk factors for both the conversion from LC to open surgery and the development of complications. These findings are consistent with that of most existing literature [9,17–19].

Body temperature serves as a crucial indicator reflecting the patient’s inflammatory status. Inflammatory reactions that infiltrate the gallbladder and surrounding tissues are a significant contributor to elevated body temperature. Additionally, the presence of other infectious factors, immune responses, or metabolic disorders can contribute to an increased body temperature. In such cases, performing LC surgery can exacerbate the patient’s inflammatory response, thus elevating the risk of complications such as intraoperative bleeding and gallbladder rupture, consequently increasing the likelihood of conversion to open surgery [20]. This observation aligns with the findings of our study.

Prolonged disease duration and recurrent episodes of ≥3 acute gallbladder attacks can lead to chronic inflammation and the worsening of gallbladder stones, potentially even progressing to gallbladder malignancy. Furthermore, these conditions often result in the formation of dense adhesions around the gallbladder and its triangle area. Such extensive adhesions present significant challenges during laparoscopic dissection, and attempting laparoscopic procedures under these circumstances can easily result in liver or intestinal ruptures, as well as bile duct injuries. This provides a plausible explanation for the heightened risk of conversion to open surgery and complications in cases in which there have been multiple acute gallbladder attacks, occurring 3 or more times.

The intricate anatomy of the gallbladder region, particularly the Calot triangle, is sometimes not easily discernible through physical examination, laboratory tests, or imaging. Nevertheless, local anatomy exhibits a positive correlation with the degree of inflammation. Moreover, as inflammation intensifies, the gallbladder wall thickens, and the surrounding anatomy becomes less distinct. This complexity significantly influences the likelihood of conversion from laparoscopic to open surgery [21]. In cases of acute cholecystitis, certain patients experience significant gallbladder distension, with portions of the gallbladder wall exceeding 5 mm in thickness. This thickness not only indicates the degree of adhesion between the gallbladder and adjacent structures but also suggests increased adhesion severity to the greater omentum and intestinal loops, thereby complicating anatomical dissection and amplifying surgical complexity. Consequently, this leads to a higher likelihood of conversion and complications. Additionally, increased wall thickness can reflect fibrosis within the gallbladder wall and may accompany gallbladder contraction or atrophy, rendering the tissue more fragile during LC. This increases the risk of bleeding and subsequent conversion to open surgery [8], in line with our study’s findings.

The presence of gallstones impacted in the neck of the gallbladder exacerbates the inflammatory response in the Calot triangle region, further complicating the anatomical landscape. During laparoscopic surgery, the surgeon’s direct tactile perception of tissues for dissection and separation becomes compromised. This impedes the precise determination of the direction and extent of dissection, elevating surgical risks and the probability of conversion to open surgery [22]. When the diameter of the common bile duct measures ≥8 mm, it often indicates wall edema, biliary infection, the presence of common bile duct lesions, or stones, some of which can require intraoperative exploration. Laparoscopic stone retrieval can prove challenging in these cases, increasing the risk of conversion to open surgery and the occurrence of bile leakage [13].

The surgeon’s expertise in laparoscopic techniques, surgical proficiency, and extensive experience are indispensable for achieving optimal outcomes in LC. Given the substantial learning curve inherent in laparoscopic surgery, reaching 200 surgical cases represents a pivotal milestone in a surgeon’s skill development. Surgeons with limited experience and lower case volumes can demonstrate constrained capabilities in executing surgical techniques, coordinating movements, and addressing intraoperative challenges [23]. Insufficient experience in managing unforeseen intraoperative circumstances can lead to errors in tissue identification under the laparoscope and an inadequate response to unexpected situations. For instance, when encountering intraoperative bleeding, inexperienced surgeons may resort to hasty clamping, resulting in inadvertent collateral damage and thereby increasing the risks of conversion to open surgery and complications. For patients with high risk, less experienced surgeons should seek assistance promptly from a senior surgeon with significant laparoscopic experience, who can either assist or lead the surgery.

The occurrence of conversion to open surgery and complications during LC cannot be entirely eliminated; rather, clinical practice should focus on minimizing these occurrences [9]. In our institution, following the implementation of a single-category surgical risk stratification for LC, a total of 820 LC surgeries were conducted. Both the conversion rate and the incidence of postoperative complications were notably lower in the low-risk group than in the high-risk group, and this difference was statistically significant (P<0.05). These findings affirm the efficacy of our scoring system and single-category surgical risk stratification in guiding clinical decision-making. It is crucial to acknowledge that this scoring system does entail a certain rate of false-positive predictions, which could lead to the conversion of some patients that could have successfully undergone LC to open surgery. While this might entail foregoing the unique benefits of LC, we firmly believe that mitigating patient distress arising from conversion or severe complications justifies the system’s application. Therefore, transparent communication and a comprehensive consideration of the pros and cons with patients and their families become paramount. In situations in which patients in the high-risk group strongly desire LC, we opt for surgery led by highly experienced surgeons with extensive laparoscopic skills, all the while consistently informing patients about the potential risks of conversion and complications, to reduce the likelihood of medical disputes.

Conclusions

In conclusion, this evaluation system is capable of significantly decreasing the incidence of complications. Rigorous preoperative assessments for LC, assessing factors that can contribute to conversion or complications, are of paramount importance. For patients at high risk, considering open surgery or involving highly experienced LC surgeons to lead the procedure is advisable. During LC, vigilant attention to conversion indications should be maintained, and any anomalies should trigger prompt conversion, to prevent severe patient injury. It must be admitted that this study also has limitations, such as selection bias in retrospective studies, small sample size in prospective studies, and insufficient long-term follow-up time. Further validation of the LC risk assessment system and surgical stratification management scale through high-quality, large-sample, multi-center, randomized controlled trials is warranted, along with integration of other rating systems.