Abstract
Introduction
Laparoscopic cholecystectomy is one of the most common procedures in general surgery and is the gold standard of care for symptomatic cholecystolithiasis, as well as for cholecystitis. The aim of this study was to analyze the surgical approach and outcomes of cholecystectomy (CE) at a university hospital and compare the findings with published national data.
Methods
We conducted a retrospective study including all patients who underwent CE between January 2008 and December 2017 at our center. Logistic regression analysis was used to evaluate risk factors for conversion. Surgical management and complications were compared with published nationwide annual reports.
Results
Of the 1,537 CEs, 881 (57.4%) were elective procedures, and 656 (42.7%) were emergency procedures. A total of 1,261 (82.2%) patients underwent minimally invasive surgery, and conversion was necessary in 10.7% (n = 135) of patients. Multivariate regression analysis revealed that preoperative biliary intervention (p < 0.001), previous abdominal surgery (p = 0.002), and male sex (p = 0.011) were independent risk factors for conversion. Compared to the German Institute for Quality Assurance and Transparency in Healthcare (AQUA Institute), we found higher rates for primary open surgery (17.9% vs. 5.0–6.8%), conversion rates (10.7% vs. 4.1–4.7%), postoperative complications (7.8% vs. 2.0–2.1%), and reinterventions (4.3% vs. 2.0–2.6%). However, our patients had significantly higher Anesthesiologists (ASA) scores (ASA III: 38.6% vs. 22.6–22.8%; ASA IV: 6.3% vs. 1.9%), more frequent preoperative biliary interventions (17.6% vs. 7.6–8.6%), and acute cholecystitis (65.6% vs. 33.8–37.2%). Mortality (1.3% vs. 0.9–1.0%) and the mean length of hospital stay (6.4 days vs. 4.7–5.2 days) did not differ significantly.
Conclusion
Our data show that CE at a university hospital can be performed with comparable mortality rates and lengths of stay in patients with more comorbidities. Our results emphasize the need for patient-tailored management in high-risk patients.
Keywords: Elective cholecystectomy, Emergency cholecystectomy, Conversion rates, Postoperative complications
Introduction
Cholecystectomy (CE) is one of the most frequently performed procedures in general surgery and is the standard treatment of symptomatic gallstones, acute and chronic cholecystitis [1–3]. Laparoscopic cholecystectomy (LC) has become the gold-standard surgical approach, offering advantages such as reduced morbidity, faster recovery, and shorter hospital stays compared to open CE [4–6]. The updated S3 guidelines by the German Society for Gastroenterology and the German Society for General and Visceral Surgery emphasize the benefits of minimally invasive approaches, including their effectiveness in both acute and chronic cases of gallstone disease, just as in acute cholecystitis [6]. These guidelines advocate for early surgical intervention, particularly in acute cholecystitis, to prevent complications and improve outcomes. Studies confirm that early laparoscopic surgery reduces the risk of recurrent symptoms and complications, while also being more cost-effective and improving quality of life [7, 8]. With respect to the timing of surgery, early surgery is currently the preferred approach stated in the German guidelines just as the Tokyo guidelines, just as other studies highlight the positive effect of early LC on postoperative morbidity [9–11].
Approximately 15–20% of patients who underwent delayed CE experienced persistent or recurrent symptoms that required further interventions prior to scheduled surgery [12–14]. In cases in which LC may pose a risk or endanger the patient, it may be necessary to switch to an open approach. Studies have shown that in 2%–15% of LC, surgeons convert during the operation for various reasons [7, 8, 15]. In most cases, conversion occurs due to the presence of peritoneal adhesions or acute cholecystitis [3, 16, 17].
In Germany, nearly 1 in 5 people have gallbladder stones [12], which are usually asymptomatic. However, when symptoms occur, current guidelines recommend CE to avoid serious or sometimes life-threatening complications such as cholangitis and biliary pancreatitis [13, 18]. Given the prevalence of gallbladder stones, it is not surprising that CE is one of the most frequently performed procedures in general surgery, with an estimation of 170,000 cases per year in Germany [19], compared to the USA, where 503,000 were reported per year [20], and Taiwan, where approximately 700,000 operative procedures are reported annually [21].
The German Institute for Quality Assurance and Transparency in Healthcare (AQUA Institute) has implemented nationwide quality monitoring, focusing on indicators like surgical conversion rates and complication management, to comprehensively document and evaluate the quality of this procedure in Germany from 2009 onward. These benchmarks facilitate comparisons across institutions and promote evidence-based improvement initiatives in care delivery. Conversion from laparoscopic to open surgery, although rare, remains a concern due to its association with higher complication rates, prolonged recovery, and increased mortality [22, 23].
These nationwide data are publicly available and can potentially prompt a discussion about the quality of CE at different institutions, with a focus of analysis or documentation on individual quality parameters such as the need for intraoperative conversion from laparoscopic to conventional CE. This study aims to evaluate the surgical outcomes, morbidity, and mortality of CE at a single tertiary care center, comparing findings with national data and providing insights into managing high-risk patients effectively.
Methods
Study Design and Objectives
The primary objective of this study was to evaluate the quality and outcomes of CE performed at a university hospital over a 10-year period, focusing on key metrics such as conversion rates from laparoscopic to open surgery, postoperative complications, mortality rates, and length of hospital stay. These parameters were compared with national benchmarks from AQUA data to assess institutional performance relative to nationwide standards. The secondary objective aimed to identify and analyze risk factors associated with conversions, including preoperative bile duct interventions, American Society of Anesthesiologists (ASA) scores, patient demographics (e.g., age and sex), and comorbidities such as elevated body mass index (BMI), diabetes, and cardiovascular disease. Furthermore, the study explored the impact of institutional differences, particularly the treatment of a higher proportion of high-risk and emergency cases, on these outcomes, providing a comprehensive understanding of factors influencing CE management.
Study Center
Ulm University Hospital serves as a tertiary referral center for surrounding region of Bavaria and Baden-Wuerttemberg. It primarily manages patients who require advanced or specialized care. The department of General and Visceral Surgery included approximately 15 surgeons with expertise in minimally invasive and open surgical techniques, with CE being one of the most frequent operations, which is performed more than 200 times per year, including the primary and secondary cholecystectomies. The hospital handles both routine and high-complexity cases, both elective and emergency surgeries, and those with significant comorbidities. Ulm University Hospital works as a key training site for medical students, residents, and fellows, which impacts its patient demographics, as some procedures may be performed under supervision of the attending by less experienced surgeons during residency. The center is equipped with state-of-the-art facilities, including advanced laparoscopic systems, and functions as a referral hub for challenging cases across the region.
Study Population
Between 2008 and 2017, 2,445 CEs were performed, with the main analysis focusing on 1,537 primary CEs aligned with national data. Inclusion criteria encompassed patients of all age-groups (>18 years) with symptomatic cholelithiasis, acute or chronic cholecystitis, or gallstone-related complications such as pancreatitis or choledocholithiasis. Both emergency and elective procedures were considered to provide a comprehensive analysis of surgical outcomes. Exclusion criteria ensured a focused dataset by excluding patients undergoing secondary CE as part of other major surgeries and cases with incomplete medical records. Additionally, duplicate records and non-indicated procedures unrelated to gallbladder pathology were excluded.
Patient Characteristics and Recorded Items
All patients who underwent CE at our department between 2008 and 2017 were retrospectively identified from our database and screened for the International Classification of Procedures in Medicine (ICPM) code for CE (5–511). Patients who underwent simultaneous open (5–511.4) or laparoscopic (5–511.5) CE during another operation were excluded from the analyses.
The primary indications for CE in our study were consistent with those established in the literature for symptomatic gallbladder disease, which included symptomatic cholecystolithiasis, acute cholecystitis, chronic cholecystitis, gallstone-related complications, such as choledocholithiasis, gallstone pancreatitis, or biliary obstruction, requiring CE as definitive management after initial stabilization. Indications were determined based on clinical presentation, imaging findings (ultrasound or cross-sectional imaging), and preoperative assessments, ensuring alignment with evidence-based guidelines for gallbladder disease management [6].
CE comprises the following operative procedures: laparoscopic dissection of the gallbladder, clipping and division of the cystic duct and artery, and removal of the gallbladder from the liver bed. All clinical data were retrospectively collected from a prospective database. The collected data included demographics, ASA score, weight, height, BMI, previous abdominal surgery, indication for surgery, history of bile duct intervention, type of operation, comorbidities, anticoagulation status, intraoperative and postoperative clinical data, reason for conversion, postoperative morbidity and mortality, reintervention, duration from admission to surgery, and length of hospital stay.
The data were retrospectively processed by a research team comprising surgeons and clinical researchers. Patient information was retrieved from the hospital’s electronic medical records, including operative reports, discharge summaries, and preoperative assessments. The data were cleaned to exclude incomplete or duplicate records and structured into a standardized database for analysis.
External Data for Comparison
The German Institute for Quality Assurance and Transparency in Healthcare (AQUA Institute) publishes annual reports on nationwide evaluations of documentation-required procedures as part of an external inpatient quality assurance program (data available at www.aqua-institut.de). Among these procedures, cholecystectomies performed in Germany are recorded and analyzed, providing comprehensive insights into quality indicators and descriptive analyses that inform decisions and foster quality improvement in healthcare [14, 19, 24, 25]. For our study, we utilized the nationwide results of the AQUA Institute from 2010, 2011, 2013, and 2014, comparing them with our own results from the corresponding years.
Introduced approximately 20 years ago, the AQUA quality reports monitor case numbers, evaluate procedural quality, and identify institutional challenges by benchmarking hospital performance against national averages. These reports are financed primarily through Germany’s statutory health insurance system under the mandate of the Federal Joint Committee (G-BA), the highest decision-making body in the German healthcare system. Hospitals are required to submit standardized data on specific procedures, including CE, which the AQUA Institute processes and analyzes. The evaluations focus on outcomes such as complication rates, conversions, and mortality, ensuring a comprehensive assessment of hospital performance. These findings, published annually, provide transparency and support quality improvement initiatives across healthcare institutions while enabling informed decision-making and benchmarking at the national level.
Statistical Analysis
The statistical analysis was performed using IBM SPSS Statistics (version 29.0.2.0 [20] SPSS Inc., Chicago, IL, USA). Descriptive statistics were calculated using median, maximum, and minimum values for quantitative data, while absolute and relative frequencies were reported for qualitative data. The normal assumption was checked based on graphical histogram and QQ-plot analysis. Explorative chi-square tests or Welch’s t test were employed to determine statistical significance when comparing our patient cohort to the external numbers of the AQUA reports. For all analyses, statistical significance was defined to p < 0.05 in a fully exploratory manner. To examine potential risk factors for conversion from laparoscopic to open surgery, both univariate and multivariable logistic regression were used. The difference in procedure (emergency vs. elective) has been treated as an independent covariate in the logistic regression analysis. Odds ratios and 95% confidence intervals were reported for these analyses. Variables that were statistically significant or at least showed the tendency (p < 0.1) in the univariate analysis were included in multivariable model.
Results
During the study period, a total of 2,245 cholecystectomies were performed at our institution, including 1,537 primary cholecystectomies and 908 procedures performed concomitantly with other major operations displayed in Figure 1. The baseline characteristics of our cohort, including age, BMI, comorbidities, preoperative anticoagulation therapy, and length of stay, are displayed in Table 1.
Fig. 1.
Consort flowchart diagram.
Table 1.
Baseline data of all primary cholecystectomies including elective and emergency procedures
| N = 1,537, n (%)a | |
|---|---|
| Primary cholecystectomies | 1,537 (100.0) |
| Median age (r), years | 56 (19–96) |
| Median BMI (r), kg/m2 | 27.8 (14–63) |
| Obesity grade 1 | 309 (20.0) |
| Obesity grade 2 | 101 (6.6) |
| Obesity grade 3 | 65 (4.2) |
| Comorbidities | |
| Abdominal | 805/1,537 (52.4) |
| Diabetes | 1,029/1,537 (65.1) |
| Infectious | 206/1,537 (13.4) |
| Hematological | 33/1,537 (2.1) |
| Hepatic | 76/1,537 (4.9) |
| Cardiac | 117/1,537 (7.6) |
| Pulmonal | 292/1,537 (19.0) |
| Renal | 223/1,537 (14.5) |
| Vascular | 239/1,537 (15.5) |
| Previous abdominal surgery | 164/1,537 (10.7) |
| No comorbidities | 486/1,537 (31.6) |
| Anticoagulation therapy | 354/1,537 (23.0) |
| Length of stay | |
| Laparoscopic () | 4.1 (SD 4.2, range 0–38) |
| Conversion () | 9.9 (SD 10.8, range 3–79) |
| Primary open () | 14.0 (SD 15.16, range 3–57) |
ASA, American Society of Anesthesiologists; SD, standard deviation; r, range; (), mean.
aData are presented as n (%) unless indicated otherwise.
Conversion rates and reasons for conversion in elective CE, displayed in Table 2, and for emergency cholecystectomy, displayed in Table 3, show how many patients needed conversion from each ASA group, gender and how many had previous abdominal surgery, preoperative bile duct intervention, and preoperative anticoagulation. Among the primary cholecystectomies, 881 were elective procedures, and 656 were performed as emergencies. Of the total primary procedures, 1,261 were initiated laparoscopically, with 135 requiring conversions to open surgery. The remaining 276 primary cholecystectomies were performed as primary open surgeries (shown in Tables 2, 3).
Table 2.
Conversion rates and reasons for conversion in elective CE
| Primary CEs | N = 1,537, n (%)a |
|---|---|
| Elective | 881/1,537 (57.3) |
| Laparoscopic | 791/881 (89.8) |
| Conversion | 52/881 (5.9) |
| Primary open | 38/881 (4.3) |
| Conversion in elective CE | N = 52, n (%)a |
|---|---|
| ASA status | |
| ASA I | 5/52 (9.6) |
| ASA II | 22/52 (42.3) |
| ASA III | 24/52 (46.2) |
| ASA IV | 1/52 (1.9) |
| Gender | |
| Male | 33/52 (63.4) |
| Female | 19/52 (36.5) |
| Preoperative bile duct intervention | 19/52 (36.5) |
| Previous abdominal surgery | 27/52 (51.9) |
| Anticoagulation | 12/52 (23.1) |
| Reason for conversion | 52/881 (5.9) |
| Adhesions | 32/52 (61.5) |
| Perforation/inflammation | 8/52 (15.4) |
| Anatomy | 7/52 (13.5) |
| Adjacent organs | 2/52 (3.8) |
| Bleeding | 1/52 (1.9) |
| Liver abscess | 1/52 (1.9) |
| N/A | 1/52 (1.9) |
ASA, American Society of Anesthesiologists.
aData are presented as n (%), if not indicated otherwise.
Table 3.
Conversion rates and reasons for conversion in emergency CE
| Primary CEs | N = 1,537, n (%)a |
|---|---|
| Emergency | 656/1,537 (42.7) |
| Laparoscopic | 335/656 (51.1) |
| Conversion | 83/656 (12.7) |
| Primary open | 238/656 (36.3) |
| Conversion in emergency CE | N = 83, n (%)a |
|---|---|
| Conversion in emergency CE | 83/656 (12.6) |
| ASA status | |
| ASA I | 5/83 (6.0) |
| ASA II | 24/83 (28.9) |
| ASA III | 49/83 (59.0) |
| ASA IV | 5/83 (6.0) |
| Gender | |
| Male | 54/83 (65.0) |
| Female | 29/83 (34.9) |
| Preoperative bile duct intervention | 20/83 (24.1) |
| Previous abdominal surgery | 32/83 (38.6) |
| Anticoagulation | 27/83 (32.5) |
| Reason for conversion | 83/656 (12.7) |
| Perforation/inflammation | 31/83 (37.3) |
| Adhesion | 27/83 (32.5) |
| Anatomy | 17/83 (20.5) |
| Neighboring organs | 1/83 (1.2) |
| Obesity | 1/83 (1.2) |
| Bleeding | 3/83 (3.6) |
| Liver cirrhosis | 1/83 (1.2) |
| N/A | 2/83 (2.4) |
ASA, American Society of Anesthesiologists.
aData are presented as n (%) unless indicated otherwise.
Conversion from laparoscopic to open surgery occurred in both elective and emergency procedures, with adhesions and acute inflammation or perforation being the most frequently documented reasons. Patients in the primary open surgery group were older, on average, than those undergoing laparoscopic surgery, while patients in both the elective and emergency conversion groups had an ASA score of ≥III, compared to their respective minimally invasive groups (shown in Tables 2, 3).
Patients who underwent elective surgery were, on average, younger than those who underwent emergency surgery were (51.7 vs. 61.9 years, p = 0.0001). Patients who underwent primary open surgery were, on average, older in both groups (elective and emergency) than patients in the other groups were (65.2 years in the elective group and 70.1 years in the emergency group). The patients in the minimally invasive group were not only younger but also predominantly female (average age of 55.5 years). Patients in both conversion groups were also older than those who underwent primary laparoscopy (59.5 in the elective group and 64.2 in the emergency group) (shown in Table 4).
Table 4.
Results of binary logistic regression analysis for “conversion”
| Predictor | Univariate | Multivariableb | ||||
|---|---|---|---|---|---|---|
| ORa | 95% CI | p value | ORa | 95% CI | p value | |
| Sex | ||||||
| Male vs. female | 2.42 | 1.68–3.51 | <0.001 | 1.71 | 1.13–2.59 | 0.011 |
| Age | 1.02 | 1.01–1.03 | <0.001 | 1.00 | 0.99–1.02 | 0.849 |
| Preoperative bile duct intervention | 1.97 | 1.30–2.91 | 0.001 | 2.21 | 1.41–3.43 | <0.001 |
| ASA score | ||||||
| II | 2.48 | 1.28–5.27 | 0.011 | 1.48 | 0.72–3.28 | 0.306 |
| III | 3.82 | 2.03–7.98 | <0.001 | 1.64 | 0.76–3.81 | 0.223 |
| IV and V | 1.74 | 0.58–4.81 | 0.298 | 0.34 | 0.08–1.24 | 0.113 |
| Cholecystitis | 0.25 | 0.17–0.35 | <0.001 | 0.49 | 0.16–1.90 | 0.250 |
| Perforated cholecystitis | 3.29 | 2.10–5.05 | <0.001 | 2.12 | 0.66–8.50 | 0.241 |
| Gallbladder empyema | 2.66 | 0.87–6.69 | 0.055 | 2.14 | 0.45–10.50 | 0.334 |
| Ulcerative/phlegmonous/abscessing cholecystitis | 2.05 | 1.33–3.12 | 0.001 | 1.52 | 0.48–6.02 | 0.512 |
| Adenocarcinoma/cholangiocellular carcinoma/metastasis | 1.61 | 0.25–5.90 | 0.535 | | | |
| Gangrenous/necrotizing cholecystitis | 1.87 | 1.03–3.20 | 0.029 | 1.58 | 0.46–6.64 | 0.499 |
| Contracted gallbladder | 2.61 | 0.13–17.79 | 0.393 | | | |
| Cardiac comorbidity | 1.90 | 1.29–2.78 | 0.001 | 1.18 | 0.74–1.88 | 0.488 |
| Renal comorbidity | 1.75 | 1.11–2.73 | 0.014 | 1.18 | 0.70–1.94 | 0.532 |
| Hepatic comorbidity | 0.99 | 0.47–1.85 | 0.972 | | | |
| Pulmonary comorbidity | 1.43 | 0.89–2.23 | 0.126 | | | |
| Abdominal comorbidity | 0.82 | 0.8–1.17 | 0.280 | | | |
| Vascular comorbidity | 1.35 | 0.78–2.24 | 0.258 | | | |
| Infectious comorbidity | 0.71 | 0.11–2.40 | 0.645 | | | |
| Hematological comorbidity | 1.32 | 0.57–2.65 | 0.476 | | | |
| Diabetes mellitus | 1.74 | 1.09–2.70 | 0.016 | 1.18 | 0.71–1.93 | 0.507 |
| Anticoagulation therapy | 1.50 | 0.99–2.22 | 0.047 | 0.85 | 0.52–1.40 | 0.529 |
| Emergency operation | 2.35 | 1.64–3.41 | <0.001 | 1.12 | 0.69–1.80 | 0.645 |
| CD | ||||||
| 2 vs. 1 | 2.62 | 1.53–4.32 | <0.001 | 1.38 | 0.74–2.46 | 0.291 |
| 3a vs. 1 | 1.77 | 0.52–4.62 | 0.296 | 0.93 | 0.25–2.77 | 0.901 |
| 3b vs. 1 | 3.01 | 1.33–6.16 | 0.004 | 1.16 | 0.44–2.82 | 0.751 |
| 4a vs. 1 | 2.25 | 0.34–8.53 | 0.296 | 0.86 | 0.11–3.98 | 0.865 |
| 4b vs. 1 | 1.77 | 0.27–6.45 | 0.456 | 2.20 | 0.28–11.67 | 0.389 |
| 5 vs. 1 | 0.82 | 0.13–2.79 | 0.794 | 1.69 | 0.23–7.85 | 0.543 |
| Obesity | ||||||
| Grade 1 | 1.08 | 0.68–1.67 | 0.734 | | | |
| Grade 2 | 0.93 | 0.41–1.87 | 0.856 | |||
| Grade 3 | 1.74 | 0.78–3.48 | 0.140 | |||
| Length of hospital stay, days | 1.03 | 1.01–1.04 | <0.001 | 1.02 | 1.00–1.04 | 0.095 |
| Previous abdominal operations | 1.77 | 1.23–2.53 | 0.002 | 1.88 | 1.26–2.81 | 0.002 |
p values in bold indicate p < 0.05.
CD, Clavien-Dindo.
aOR >1 indicates an increased likelihood of conversion.
bMultivariable model included all variables from univariate models with p < 0.1.
Logistic regression analysis identified male sex, higher ASA scores, acute cholecystitis, emergency operation, preoperative bile duct intervention, previous abdominal surgery, and anticoagulation therapy as factors associated with conversion. Multivariate analysis confirmed preoperative bile duct intervention, prior abdominal surgery, and male sex as independent risk factors for conversion (shown in Table 4).
Compared with the national registry data, patients at our institution were treated significantly more often via primary opening and were also converted more frequently (shown in Table 5). Table 5 displays the data on complications compared with the available AQUA data. Interestingly, the incidence of general postoperative complications was significantly greater at our institution, than at the other institutions, according to the registry data (Table 5). The incidence of complications after conventional CE was quite similar compared to the national benchmark. The overall reintervention rate was below 5% and the reintervention rate after conventional CE was also significantly higher than the national average. However, the reintervention rate after LC was comparable (shown in Table 5).
Table 5.
Comparison of complications and mortality
| Institution | UKU | AUQA | AQUA | AQUA | AQUA | p value |
|---|---|---|---|---|---|---|
| year | 2008–2017 | 2010 | 2011 | 2013 | 2014 | |
| n | 1,537, n (%)a | 171,519, n (%)a | 173,296, n (%)a | 173,375, n (%)a | 176,097, n (%)a | |
| Primary cholecystectomies | 1,537 (100.0) | 171,519 (100.0) | 173,296 (100.0) | 173,375 (100.0) | 176,097 (100.0) | |
| Laparoscopic | 1,261 (82.0) | 151,483 (88.3) | 153,912 (88.8) | 156,742 (90.4) | 159,997 (90.9) | <0.001 |
| Conversion | 135 (10.7) | 8,035 (5.3) | 7,738 (5.0) | 7,220 (4.6) | 7,141 (4.4) | <0.001 |
| Primary open | 276 (17.9) | 11,731 (6.8) | 11,350 (6.5) | 8,786 (5.0) | 9,213 (5.3) | <0.001 |
| General postoperative complications | 120 (7.8) | 4,938 (2.9) | 5,212 (3.0) | 4,839 (2.8) | 4,841 (2.8) | <0.001 |
| General postoperative complications after conversion | 21 (15.6) | 3,194 (2.0) | 3,357 (2.1) | 3,394 (2.1) | 3,389 (2.0) | <0.001 |
| General postoperative complications after conventional CE | 52 (18.8) | 1,169 (14.5) | 1,790 (15.8) | 1,407 (15.3) | 1,419 (16.3) | 0.024 |
| Reintervention rate | 66 (4.3) | 3,351 (2.0) | 3,441 (2.0) | 4,176 (2.4) | 45,516 (2.6) | <0.001 |
| Reintervention after laparoscopic operation | 18 (1.6) | 893 (0.9) | 890 (0.9) | 1,168 (1.2) | 1,252 (1.3) | 0.001 |
| Reintervention after conventional CE | 48 (17.4) | 829 (7.1) | 860 (7.6) | 782 (8.5) | 846 (9.7) | <0.001 |
| Mortality | 20 (1.3) | 1,625 (0.9) | 1,701 (1.0) | 1,557 (0.9) | 1,592 (0.9) | 0.133 |
| Cholecystitis | 1,008 (65.6) | 58,320 (34.0) | 58,580 (33.8) | 63,690 (36.7) | 65,485 (37.2) | <0.001 |
All p values were calculated using chi-square test; p values refer to the comparison between data from the University Hospital Ulm (UKU) and the aggregated AQUA data from all available years combined.
aData are presented as n (%) unless indicated otherwise.
Sex, ASA score, preoperative bile duct intervention, pathological evaluation, mortality rates, and length of stay are displayed in Table 4 in comparison with the nationwide data. When comparing patient characteristics, it is clear that our patient cohort had more comorbidities. Only approximately half of our patients had an ASA I + II score, whereas 75% of the patients in the registry data had an ASA I + II score (Table 6).
Table 6.
Comparison of baseline and perioperative specific outcomes and length of stay
| | UKU | AQUA | AQUA | AQUA | AQUA | p value |
|---|---|---|---|---|---|---|
| 2008–2017, n (%)a | 2010, n (%)a | 2011, n (%)a | 2013, n (%)a | 2014, n (%)a | ||
| Primary cholecystectomies | 1,537 (100.0) | 171,519 (100.0) | 173,296 (100.0) | 173,375 (100.0) | 176,097 (100.0) | |
| Sex | ||||||
| Female | 849 (55.2) | 110,688 (64.5) | 111,173 (64.2) | 110,034 (63.4) | 111,070 (63.1) | <0.001 |
| Male | 688 (45.8) | 60,831 (35.5) | 62,123 (35.8) | 63,341 (36.5) | 65,027 (36.9) | <0.001 |
| ASAa score | ||||||
| I | 282 (18.3) | 37,038 (21.6) | 36,745 (21.2) | 36,306 (20.9) | 35,748 (20.3) | 0.007 |
| II | 551 (35.8) | 92,386 (53.9) | 93,434 (53.9) | 94,477 (54.5) | 97,018 (55.1) | <0.001 |
| III | 593 (38.6) | 38,587 (22.5) | 39,540 (22.8) | 39,156 (22.6) | 39,734 (22.6) | <0.001 |
| IV | 97 (6.3) | 3,285 (1.9) | 3,352 (1.9) | 3,232 (1.9) | 3,381 (1.9) | <0.001 |
| V | 3 (0.2) | | | | | |
| N/A | 11 (0.7) | | | | | |
| Preoperative bile duct intervention | 272 (17.6) | 14,080 (8.6) | 14,104 (8.5) | 14,227 (8.6) | 13,348 (7.6) | <0.001 |
| Length of stay, days | ||||||
| Overall mean (SD, range) | 6.4 (8.9, 0–146) | 5.2 (0–352) | 5.1 (0–216) | 4.7 (0–312) | 4.8 (0–235) | <0.001b |
All p values are calculated using chi-square test, unless b: Welch’s t test; p values refer to the comparison between data from the University Hospital Ulm (UKU) and the aggregated AQUA data from all available years combined.
ASA, American Society of Anesthesiologists; SD, standard deviation; N/A, not applicable.
aData are presented as n (%) unless indicated otherwise.
Table 7 summarizes the complications according to the Clavien-Dindo classification system based on the procedure performed. As anticipated, elective CE cases exhibited lower postoperative complications compared to emergency procedures. Postoperative morbidity within 90 days varied across patient groups, with elective surgeries showing fewer complications overall compared to emergencies. The distribution of morbidity rates by surgical approach – laparoscopic, converted, or primarily open – is detailed in Table 7, highlighting differences in outcomes across procedural types.
Table 7.
Comparison of complications according to the surgical approach used for CE
| | N = 1,537, n (%)a |
|---|---|
| CD | |
| 90-Day overall morbidity | 317/1,537 (20.6) |
| Elective 90-day overall morbidity | 89/881 (10.0) |
| Laparoscopic | 73/791 (9.2) |
| Conversion open | 16/52 (30.8) |
| CD II | 36/881 (4.1) |
| CD IIIa | 8/881 (0.9) |
| CD IIIb | 14/881 (1.6) |
| CD IV | 0/881 (0.0) |
| CD V | 1/881 (0.1) |
| Emergency 90-day overall morbidity | 238/656 (36.3) |
| Laparoscopic | 99/656 (15.1) |
| Open | 139/656 (21.2) |
| Conversion | 40/656 (6.1) |
| CD II | 84/656 (12.8) |
| CD IIIa | 24/656 (3.6) |
| CD IIIb | 32/656 (4.8) |
| CD IV | 16/656 (2.4) |
| CD V | 31/656 (4.7) |
| Overall mortality due to CE (both elective + emergency) | 20/1,537 (1.3) |
CD, Clavien-Dindo.
aData are presented as n (%) unless indicated otherwise.
Discussion
In our 10-year retrospective analysis of CE, adhesions were the leading cause of conversion in elective cases, followed by perforation with inflammation and unclear anatomy, respectively, which is also supported by other studies [26, 27]. This highlights that preoperative assessments may not always predict intraoperative challenges, particularly adhesions. In emergency CE, perforation with inflammation was the primary reason for conversion, followed closely by adhesions. The higher rate of perforation-related conversions in emergencies reflects the critical condition of these patients and the difficulties of the laparoscopic approach, especially in acute cholecystitis. Complex anatomy is a key factor in both elective and emergency conversions, emphasizing that even in nonemergency cases, anatomical variations can necessitate open surgery, which is also supported by other recent studies [28, 29]. Notably, primary open CE accounted for only 4.3% of elective cases but 36.3% of emergency cases, suggesting careful preoperative decision-making based on the risks of laparoscopy under certain conditions.
To determine risk factors for conversion, we performed multiple regression analysis. In the present study, younger age (<60 years) and female sex positively influenced the likelihood of successful completion of laparoscopic surgery, even in emergencies. Factors such as an ASA value of ≥III, a BMI value over 25 kg/m2, prior bile duct intervention, comorbidities such as diabetes, cardiac-, and renal comorbidities, previous abdominal surgery, histology, and therapy with anticoagulants favored the frequency of conversion. These results have also been identified as risk factors in several other studies [30–34]. In the multivariate analysis of our study, only preoperative bile duct intervention, history of abdominal surgery, and male sex remained independent factors favoring conversion. These variables were also identified as risk factors in other studies [23, 35, 36]. Taking these factors into account could help tailor CE treatment more individually in the future and thus sustainably reduce the conversion rate.
In both emergency and elective cases, the postoperative bleeding rate was higher in primary open and converted operations than in successful laparoscopic operations. These findings are supported by data from a recently published study [37]. Wound healing disorders also occur less frequently in minimally invasive operations. This is one of the many advantages of minimally invasive operations and has already been scientifically proven several times [38, 39]. Most patients with primary open CE, both in elective and emergency settings, had an ASA score of ≥III, as did a significant proportion of patients in the conversion group. This finding indicates a connection between higher ASA scores and the need for open surgery, which is also suggested to be a general risk factor by another study [40]. These results highlight a potential selection bias, reflecting the severity of the patient’s condition in determining the surgical approach.
Our data revealed that 17.9% of the procedures were open operations and that 81.1% were laparoscopic procedures, for a conversion rate of 10.7%. Postoperative complications and re-interventions were observed more frequently in our cohort. At first glance, these results appear unfavorable when compared to national benchmarks, where laparoscopic procedures are more common, conversion rates are lower, and the proportion of open surgeries and complications is smaller. National data also report lower average rates for general complications and re-interventions, highlighting a significant difference from the outcomes at our institution. According to the histopathological analysis, 65.6% of the patients in our group had acute cholecystitis, whereas only 33.8–37.2% of the patients in the registry had acute cholecystitis [16, 26, 27].
A detailed analysis of our data revealed that a bit more than half of the cases were elective procedures and just below half were emergency procedures. The conversion rate for elective procedures was lower than that for emergencies. The higher conversion rate in emergency procedures is most likely due to the more complex intraoperative conditions, such as acute inflammation or perforation [30, 33, 41–44]. Postoperative complications in the group of patients who underwent elective laparoscopic procedures were comparable with the data of other analyses [37]. In the current literature, the conversion rate for elective laparoscopic cholecystectomies ranges from 5 to 7%, which aligns with our results of 5.9% [31, 32, 41].
Analysis of registry data revealed that conversion and complication rates were lower than those observed in our cohort [14, 19, 24, 25]. However, a comparison of the comorbidity profile between the two groups using the ASA score revealed that our cohort had significantly more comorbidities. A higher proportion of patients at our institution had severe conditions, as reflected by advanced ASA scores, compared to the reported national averages. Another well-established indicator for predicting a more difficult operative procedure and a more complex clinical course associated with more complications is the rate of preoperative bile duct interventions [45]. The preoperative bile duct intervention rate was more than twice as high as the nationwide reported rate [14, 19, 24, 25]. Despite the higher rate of preoperative interventions and that the total number of patients with comorbidities was high, there was no difference between the two groups in terms of length of hospital stay, just as there was no difference in mortality rates.
Limitations
This study has several limitations that must be acknowledged to contextualize the findings and guide future improvements. First, as a retrospective analysis, the study relies on pre-existing data from electronic patient records, which may be incomplete or inconsistent, potentially introducing bias. The inclusion of only a single university hospital limits the generalizability of the results as university hospitals often manage more complex and high-risk cases compared to community hospitals. This likely contributed to higher complication and conversion rates relative to national averages.
Additionally, the benchmarking data from AQUA reports, while valuable, were not available for all years within the study period, and differences in data collection methods, definitions, and patient populations between AQUA and our institution may have affected comparability. Also, the inability to perform separate subgroup analyses for elective and emergency CE cases in direct comparison with AQUA Registry data due to the lack of detailed stratification in the national dataset. This constraint limits the precision of our benchmarking and underscores the need for more granular national data to allow for more accurate institutional comparisons. Following the transition from AQUA to IQTIG (Institute for Quality Assurance and Transparency in Healthcare), there have been no standalone nationwide AQUA reports, specifically on CE in recent years. Although AQUA introduced follow-up indicators from 2015 to 2017, subsequent years have not seen publicly available national evaluations dedicated specifically to CE. Thus, recent benchmarking relies predominantly on data directly sourced from individual clinic reports or IQTIG publications, highlighting the necessity for more granular and systematically collected national data to facilitate more accurate institutional comparisons.
Another limitation is the lack of detailed information on key confounding factors, such as surgeon experience, institutional protocols, and resource availability, all of which can significantly influence surgical outcomes. Granular data on these variables were not systematically recorded in our institutional database during the study period. Factors such as surgeon experience, which significantly influence outcomes like conversion rates and postoperative complications, were not consistently documented in a structured or quantifiable manner in our dataset, thus precluding meaningful statistical analysis. We acknowledge that this represents an important limitation as surgical expertise is a critical confounder in evaluating institutional performance and should be incorporated in future prospective analyses. Similarly, variations in institutional protocols and resource availability over the 10-year study period were not explicitly tracked in a way that would permit reliable retrospective assessment.
While ASA scores were analyzed, other patient comorbidities and long-term outcomes, such as quality of life or functional recovery, were not comprehensively assessed, which addresses another limitation. Finally, the study largely confirms established trends, such as the challenges of laparoscopic surgery in emergencies, without providing novel insights into predictive factors or strategies to reduce complications and conversion rates. Addressing these limitations in future research, including through prospective studies, expanded benchmarking with similar institutions, and a focus on long-term patient outcomes, will be critical to translating findings into actionable improvements in surgical care.
Furthermore, the analysis was conducted in 2020; however, due to the onset of the COVID-19 pandemic, data from 2020 to 2022 could not be reliably incorporated as surgical practices and documentation were significantly disrupted during this time.
Conclusion
This retrospective study offers a detailed examination of CE outcomes at a university hospital over a 10-year period, with a focus on elective versus emergency procedures. The findings reveal the impact of patient demographics, surgical approach, and ASA score on surgical outcomes. Despite higher complication and conversion rates compared with national averages, the specialized care and strategic approach resulted in comparable lengths of stay and mortality rates, underscoring the effectiveness of tailored surgical management of CE in a high-risk university patient population.
Acknowledgment
This study has been part of the Rashad Khazen MD thesis.
Statement of Ethics
This study was approved by the Ethics Committee of the University Hospital Ulm (approval date 29/01/2020; protocol code 06/20). Due to the retrospective nature of the study, a patient informed consent was not required, which was approved by the Ethics Committee of the University Hospital Ulm.
Conflict of Interest Statement
M. Kornmann was a member of the journal’s Editorial Board at the time of submission.
Funding Sources
This study was not supported by any sponsor or funder.
Author Contributions
Conceptualization and methodology: K.C.S., M.K., and B.Mü.; software, visualization, and visualization: K.C.S. and B.Ma.; validation: M.K. and B.Mü.; formal analysis and resources: R.K. and B.Ma.; investigation and data curation: R.K. and K.C.S.; writing – original draft preparation: K.C.S.; writing – review and editing: B.Ma., R.K., M.K., and B.Mü.; supervision: M.K. and B.Mü.; project administration: K.C.S., M.K., and B.Mü. All authors have read and agreed to the published version of the manuscript.
Funding Statement
This study was not supported by any sponsor or funder.
Data Availability Statement
The data presented in this study are available upon request from the corresponding author.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
The data presented in this study are available upon request from the corresponding author.