Role Of Intraoperative Cholangiography Research Articles

The Role of Intraoperative Cholangiography in the Diagnosis of Incidental Choledocholithiasis and Iatrogenic Injuries to the Common Bile Duct

The Role of Intraoperative Cholangiography in the Diagnosis of Incidental Choledocholithiasis and Iatrogenic Injuries to the Common Bile Duct

Resource use for cholecystectomy with versus without cholangiography: A multicenter, propensity-matched analysis

BackgroundIntraoperative cholangiography may allow for earlier identification of common bile duct injury and choledocholithiasis. The role of intraoperative cholangiography in decreasing resource use related to biliary pathology remains unclear. This study tests the null hypothesis that there is no difference in resource use for patients undergoing laparoscopic cholecystectomy with versus without intraoperative cholangiography. MethodsThis retrospective, longitudinal cohort study included 3,151 patients who underwent laparoscopic cholecystectomy at 3 university hospitals. To minimize differences in baseline characteristics while maintaining adequate statistical power, propensity scores were used to match 830 patients who underwent intraoperative cholangiography at surgeon discretion and 795 patients who underwent cholecystectomy without intraoperative cholangiography. Primary outcomes were the incidence of postoperative endoscopic retrograde cholangiography, the interval between surgery and endoscopic retrograde cholangiography, and total direct costs. ResultsIn the propensity-matched analysis, the intraoperative cholangiography and no intraoperative cholangiography cohorts had similar age, comorbidities, American Society of Anesthesiologists Sequential Organ Failure Assessment scores, and total/direct bilirubin ratios. The intraoperative cholangiography cohort had a lower postoperative endoscopic retrograde cholangiography (2.4% vs 4.3%; P = .04), a shorter interval between cholecystectomy and endoscopic retrograde cholangiography (2.5 [1.0–17.8] vs 4.5 [2.0–9.5] days; P = .04), and shorter length of stay (0.3 [0.2–1.5] vs 1.4 [0.3–3.2] days; P < .001). Patients undergoing intraoperative cholangiography had lower total direct costs ($4.0K [3.6K–5.4K] vs $8.1K [4.9K–13.0K]; P < .001). There were no differences in 30-day or 1-year mortality among the cohorts. ConclusionCompared with laparoscopic cholecystectomy without intraoperative cholangiography, cholecystectomy with intraoperative cholangiography was associated with decreased resource use, which was primarily attributable to decreased incidence and the earlier timing of postoperative endoscopic retrograde cholangiography.

SP6.1.6 Rule of systematic intraoperative cholangiogram in patients undergoing emergency cholecystectomy

Abstract Aims Incidence of gall stone disease is estimated at 10-15%of population. Intraoperative cholangiography (IOC) diagnose choledocholithiasis, delineates the anatomy of the biliary ducts, facilitate the dissection and reduces injuries. Our aim is to assess the feasibility and role of IOC and the incidence of choledocholithiasis in acute cholecystitis (ACC). Methods Retrospective analysis of prospectively collected data for patients admitted with ACC and undergoing same-hospital-stay laparoscopic cholecystectomy (LC). IOC was systematically attempted in all cases. Results 475cases included. Female to male ratio1.9:1. Conversion to open was done in 3 cases. Preoperative cholelithiasis was confirmed in 439cases versus 34cases with no stones. USS CBD abnormality (dilated or contain stone) found in 53 cases, out of which 8(15%) cases had CBD stones. Jaundice was found in 69cases, where 25(39%) cases had confirmed choledocholithiasis. IOC was successful in all cases except one. Abnormal IOC was found in 99(21%) cases. Of those; CBD stones were confirmed in 76 (77%) cases regardless the presence of cholelithisasis on USS. Empyema was found in 237 cases and it was associated with higher risk of abnormal IOC in 59(25%) cases where CBD stones were confirmed in 45(76%) cases. Cystic duct (CD) stones found in 80cases, of those 27(34%)cases had choledocholithiasis. Conclusions Females have double the risk of ACC. Preoperative jaundice and CD stones are stronger indicators than CBD diameter for presence of choledocholithiasis. The incidence of choledocholithiasis in ACC is (20-25%) regardless the presence of gall stones on USS. IOC is feasible and highly recommended in emergency LC.

The role of Intraoperative cholangiography (IOC) and methylene blue tests in reducing bile leakage after living donor hepatectomy

AimLiver transplantation remains the only curative treatment in end stage liver disease. Biliary complications remain the most common major morbidity causes in hepatic resection. We aimed to determine and eliminate the bile leakage in donor hepatectomy of LDLT. Material and methodsThis study was conducted retrospective and one center study. The study population included 110 consequential liver donors with major liver resection (more than three segments). The population was divided into three groups for data analyses. Primary study groups included 40 donors subjected to methylene blue test starting in April 2013 and 40 donors subjected to intraoperative cholangiography started in March 2014. ResultsA total of 110 liver donors (42.7% women) were included in the study. Postoperative biliary complications were less in methylene blue and intraoperative cholangiography (IOC) groups. Bile leakage was significantly higher in control group (23.3%) compared to methylene blue (5%) and IOC groups (2%) Average duration of hospital stay and duration of operation were significantly higher in control group compared to methylene blue and IOC groups. ConclusionIn our study we conducted to establish biliary leakage in living donor hepatectomy which intraoperative cholangiography test was used to determine. Many intraoperative methods have been introduced to prevent biliary leakage and development of complications. We have showed that IOC test used in the present study could be easily applied in both living liver donor hepatectomy and other major hepatectomy cases. IOC test reduced postoperative biliary leakage incidence and did not increase incidence of other complications.

Role of Intraoperative Cholangiography in Laparoscopic Cholecystectomy in Higher Risk Patients of Bile Duct Injuries

AbstractBackground: Intraoperative Cholangiography (IOC) during Laparoscopic Cholecystectomy (LC) is a radiologic contrast-based examination of the bile duct which can represent a systemic approach to avoid Bile Duct Injuries (BDIs).Aim of Study: The aim of this study was to evaluate the protective effect of selective use of IOC during laparoscopic cholecystectomy in patients with high risk for Bile Duct Injuries (BDIs).Patients and Methods: This was a prospective study included 23 patients who presented for laparoscopic chole-cystectomy and had risk factors for bile duct injuries, under-went LC with IOC. Cases were analyzed as regard operative details and clinical outcomes.Results: Cholangiography was successful in all the cases. The mean time of IOC added to LC was 22 minutes. There was a longer LC and IOC time in cases with positive CRP, pericholecystic fluid, mucocele and pyocele with positive significant differences. Although the pre-operative data 47.8% had history of obstructive jaundice, 21.7% a mucocele cases, 17.4% a pyocele cases, pericholecystic fluid in 30.4% and dilated CBD in 65.2%, only 13% showed abnormal IOC and needed further therapies (intraoperative ERCP in 2 cases and CBD exploration in 1 case). No bile duct injury in any case.Conclusion: Intraoperative Cholangiography (IOC) was found to be safe, taking only an additional time of 22 minutes to total operative time. Although the pre-operative data, only 13% of cases needed further therapies (ERCP or CBD explo-ration). The use of IOC could be considered to improve patient safety and long term results.

The role of intraoperative cholangiography in patients undergoing laparoscopic cholecystectomy for acute gallstone pancreatitis: is magnetic resonance cholangiopancreatography needed?

Intraoperative cholangiography is sporadically used in patients undergoing laparoscopic cholecystectomy to delineate common bile duct anatomy and exclude retained stones. In patients with acute gallstone pancreatitis, intraoperative cholangiography may reduce the need for preoperative magnetic resonance cholangiopancreatography. A retrospective review of a prospectively collected patient database was undertaken over a 15-year period. The primary objective was to evaluate intraoperative assessment of the common bile duct with intraoperative cholangiography in patients with acute gallstone pancreatitis. A total of 2215 patients underwent laparoscopic cholecystectomy between October 1998 and December 2013; 113 patients (of whom 77 were women) with a mean age of 54 years (range 16-88 years) were diagnosed with acute gallstone pancreatitis. Of these, 102 patients (90%) underwent laparoscopic cholecystectomy with intraoperative cholangiography, which was normal in 89 cases. Thirteen patients had choledocholithiasis on intraoperative cholangiography, 11 of whom were managed with concomitant trans-cystic duct exploration and clearance. Two patients required postoperative endoscopic retrograde cholangiopancreatography. In patients diagnosed with acute gallstone pancreatitis, it is reasonable to proceed directly to surgery using intraoperative cholangiography on the same admission as the definitive assessment of the common bile duct. This negates the need for magnetic resonance cholangiopancreatography and can translate into cost savings and reduced length of stay.

Role of intraoperative cholangiography for detecting residual stones after biliary pancreatitis: still useful? A retrospective study

BackgroundIntraoperative cholangiography (IOC) may detect residual stones in the common bile duct (CBD) after acute biliary pancreatitis (ABP). The aim of the present study is to analyze the utility of IOC in detecting residual stones in patients undergoing cholecystectomy for ABP and if complications are related with this procedure.MethodsDemographic and clinical factors were assessed in patients with mild ABP who underwent IOC during laparoscopic cholecystectomy. Factors assessed included preoperative size of the CBD on ultrasonography, presence of stones in the gallbladder and the CBD, and IOC results. For the statistical analysis, χ2 or Fisher’s exact tests to compare proportions and the nonparametric Mann–Whitney U test for analysis of values with abnormal distribution were used.ResultsThe study included 113 patients, 82 males (72.6%) and 31 females (27.4%), of mean age 46.9 ± 14.7 years (range 18–86 years). All preoperative laboratory indicators were elevated. The group of the patients with stones in the CBD diagnosed by IOC was divided in patients with diameters <0.8 mm and with diameters ≥0.8 mm of the CBD diagnosed preoperatively with ultrasound. The laboratory tests do not demonstrate difference statistically significative between these two groups. The group of the patients without stones in the CBD diagnosed by IOC was also divided in patients with diameters <0.8 mm and with diameters ≥0.8 mm of the CBD. Also in these two groups, the statistical analysis of the laboratory tests does not demonstrate significative difference. Most procedures were performed by specialists (64.6%), and all patients underwent IOC. IOC showed stones in 84/113 patients (74.3%). A comparison of patients with and without stones at IOC showed similar mean times from hospitalization to surgery (5.9 days [range 2–12 days] vs. 6.1 days [range 2–23 days]), from surgery until hospital discharge (2.0 days [range 0–4 days] vs. 2.2 days [range 0–11 days]), and overall length of stay (7.9 days [range 3–19 days] vs. 8.3 days [range 3–23 days]) (P > 0.001).ConclusionsIOC is useful to diagnose residual CBD stones, without increasing complications related to the procedure itself.

Роль магнитно-резонансной холангиопанкреатографии в предоперационной диагностике холедохолитиаза у пациентов, готовящихся к лапароскопической холецистэктомии

The capabilities of different methods of preoperative diagnostics of choledocholithiasis are considered in the given article. Both routine (transabdominal ultrasound, fibrogastroduodenoscopy and others) and relatively new methods (magnetic resonance cholangiopancreatography (MRCP) and endoscopic ultrasonography (EUS)) are described from the point of view of their role in solving the problem of timely preoperative diagnostics of choledocholithiasis, as well as the role of intraoperative cholangiography (IOC) in its historical perspective. Particular attention is paid to the informativity of combined application of magnetic resonance cholangiopancreatography and endoscopic ultrasonography in detecting hepatobiliary zone pathology. The role of magnetic resonance imaging (MRI) in detecting hepatobiliary zone pathology and its high accuracy in preoperative diagnostics of choledocholithiasis is emphasized. Current statistical data concerning the use of MRI in the health care system of the Russian Federation are provided in the article. Based on the attained results the authors conclude that the complex of diagnostic program for patients with suspected choledocholithiasis, undergoing laparoscopic cholecystectomy, should include magnetic resonance cholangiopancreatography, besides routine diagnostic techniques. Endosonography should complement magnetic resonance imaging when there is need for updating the diagnosis. Retrograde cholangiopancreatography should be used in case of uninformative magnetic resonance cholangiography and endoscopic sonography. This approach improves considerably the diagnostic accuracy of studies and reduces the number of invasive diagnostic procedures. Key words Сholedocholithiasis, magnetic resonance сholangiopancreatography (MCRP), magnetic resonance imaging (MRI), endosonography (EUS), laparoscopic cholecystectomy, mini-invasive technologies

Role of Intraoperative Cholangiography in Patients Whose Biliary Tree Was Evaluated Preoperatively by Magnetic Resonance Cholangiopancreatography

Routine performance of intraoperative cholangiography (IOC) during cholecystectomy is controversial. The aim of this study was to evaluate the role of IOC during cholecystectomy in addition to preoperative magnetic resonance cholangiopancreatography (MRCP) in our institution over a 12-year period. A total of 425 consecutive patients who underwent IOC during cholecystectomy were included in this study. MRCP was performed preoperatively for bile duct evaluation in all patients. When common bile duct (CBD) stones were detected, they were removed endoscopically before the operation. We estimated the results of IOC in terms of the success rate, the detection rate of anatomic abnormality of the biliary system, and the incidence of residual CBD stones. MRCP preoperatively identified 6 (1.4 %) patients with abnormal biliary systems and 56 with CBD stones, which were endoscopically removed. The success rate of IOC was 93.8 % (399/425). Abnormalities of the biliary system were detected in 12 patients (12/399, 3.0 %) and CBD stones in 8 (8/399, 2.0 %). Of the eight patients with stones, seven had been examined by endoscopy preoperatively and found to have CBD stones. The detection rate of bile duct stones in patients with preoperative endoscopic removal of CBD stones (7/56, 12.5 %) was significantly higher than those with CBD stones first detected during IOC (1/365, 0.3 %) (p < 0.01). Moreover, no residual CBD stones were detected in patients who were operated on within fewer than 12 days from endoscopic treatment to the operation. IOC is indicated even after preoperative sphincterotomy for CBD stones. In our study, it resulted in a 12.5 % incidence of persistent stones after sphincterotomy. IOC plays an additional role in detecting CBD stones and in revealing abnormalities of the biliary tree in patients whose biliary tree was preoperatively evaluated by MRCP.

Variation in the Use of Intraoperative Cholangiography During Cholecystectomy

The role of intraoperative cholangiography (IOC) in prevention of common bile duct (CBD) injuries and the management of CBD stones is controversial, and current variation in use of IOC has not been well described. Multilevel hierarchical models using data from the Texas Hospital Inpatient Discharge Public Use data files (2001 to 2008) were used to evaluate the percentage of variance in the use of IOC that was attributable to patient, surgeon, and hospital factors. A total of 176,981 cholecystectomies were performed in 212 hospitals in Texas. There was wide variation in IOC use, ranging from 2.4% to 98.4% of cases among surgeons and 3.7% to 94.8% of cases among hospitals, even after adjusting for case mix differences. The percentage of variance in IOC use attributable to the surgeon was 20.7% and an additional 25.7% was attributable to the hospital. IOC use was associated with increased age, gallstone pancreatitis or CBD stones, Hispanic race, decreased illness severity, insurance, and later year of cholecystectomy. ERCP (24.0% vs 14.9%, p < 0.0001) and CBD exploration (1.63% vs 0.42%, p < 0.0001) were more commonly performed in patients undergoing IOC. Uncertainty regarding the benefit of IOC leads to wide variation in use across surgeons and hospitals. The surgeon and hospital are more important determinants of IOC use than measured patient characteristics. Our study highlights the need for further evaluation of comparative effectiveness of IOC in the prevention of CBD injuries and retained stones, taking into account patient risk factors, surgeon skill, cost, and availability of local expertise.

Laparoscopic Cholecystectomy Without Intraoperative Cholangiography

The role of intraoperative cholangiography (IOC) during laparoscopic cholecystectomy (LC) remains controversial. This study evaluates the outcomes of a management policy of LC without IOC. Patients with symptomatic cholecystolithiasis were classified regarding their potential risk for choledocholithiasis, and those at low risk received no further investigations, whereas medium- and high-risk patients underwent preoperative magnetic resonance cholangiopancreatography (MRCP) and/or endoscopic retrograde cholangiopancreatography (ERCP) with duct clearance. Those who required duct exploration were excluded. LC proceeded without IOC. Data were collected prospectively. Between 2002 and 2011, 717 consecutive patients underwent LC; 168 (23.4%) were classified as medium or high risk, and 57 of those had preoperative duct clearance at ERCP. The conversion rate from LC to open surgery was 4.7%. The morbidity rate was 3.9%, and there were no mortalities. Nineteen patients in the low-risk group were re-admitted, of whom three patients (0.4% of 717 patients) had choledocholithiasis on ERCP. Minor bile duct injury occurred in 3 patients, and a fourth developed ischemic bile duct stricture 7 months following open conversion. The selective use of preoperative MRCP and ERCP to detect and treat choledocholithiasis facilitates the safe application of a policy of LC without IOC. Careful operative technique is necessary to avoid duct injury.

Role of intraoperative cholangiography in laparoscopic cholecystectomy.

The results of a policy of selective cholangiography were assessed in 400 patients undergoing laparoscopic cholecystectomy. Preoperative endoscopic retrograde cholangiopancreatography (ERCP) was performed in 81 patients (20 per cent) of whom 31 (38 per cent) showed definite or possible evidence of stones in the bile duct. Seventeen of the 400 patients underwent intraoperative cholangiography and the majority of these (12) were normal. After a minimum follow-up of 1 year, 17 patients (4 per cent) have had ERCP for suspected residual duct stones. Eight (2 per cent) of these revealed stones and all were successfully treated with sphincterotomy and duct clearance. Preoperative and postoperative ERCP was not associated with mortality or major morbidity. No major duct injury occurred and none was diagnosed within 2 years of operation. Routine intraoperative cholangiography is not a necessary part of laparoscopic cholecystectomy in the presence of an efficient and safe ERCP service.

Selective operative cholangiography in the performance of laparoscopic cholecystectomy

The objective of this prospective study was to evaluate the role of intraoperative cholangiography (IOC) for patients undergoing laparoscopic cholecystectomy (LC) to determine whether it could be safely omitted for all patients who fit standard criteria, namely normal liver function tests, no history of gallstone pancreatitis, common bile duct (CBD) diameter less than 10 mm or previous history of jaundice. Data were collected prospectively from 194 consecutive patients who had LC for symptomatic gall bladder disease. IOC was not performed in any patient. The conversion rate was 6.1% and one CBD injury occurred. Our experience demonstrates that LC performed without routine IOC does not result in an increased incidence of retained stones in selected patients who have no history of pancreatitis, normal liver function tests and CBD less than 10 mm diameter.

Contemporary Minimally Invasive Approaches to the Management of Acute Cholecystitis: A Review and Appraisal

Acute cholecystitis is one of the most common emergency admissions in surgical practice. This review appraises the available evidence from the English-language literature regarding the minimally invasive approaches to the management of this condition. The following aspects of care are reviewed and appraised: (1) the diagnostic criteria for acute cholecystitis, (2) the optimal timing for cholecystectomy (early, delayed, or interval surgery), (3) the optimal approach to cholecystectomy (laparoscopic versus open), (4) the role of intraoperative cholangiography, and (5) the management of patients unfit for surgery.

The Role of Intraoperative Cholangiography in Detecting and Preventing Bile Duct Injury during Laparoscopic Cholecystectomy

The Role of Intraoperative Cholangiography in Detecting and Preventing Bile Duct Injury during Laparoscopic Cholecystectomy

Comparative Evaluation of Contact Ultrasonography and Transcystic Cholangiography During Laparoscopic Cholecystectomy: A Prospective Study

The role of intraoperative cholangiography (IOC) during laparoscopic cholecystectomy (LC) is controversial. While many advocate its routine use, others argue for a selective approach. Recent reports showed laparoscopic contact ultrasonography (LCU) as a viable alternative to IOC. However, no prospective data were available to compare the accuracy, efficacy, and safety of the two diagnostic procedures. To evaluate the benefits and disadvantages of LCU and IOC during LC. Seventy-eight patients who underwent LC at Pisa (Italy) and Dundee (Scotland) university hospitals were entered in a prospective data registry. Details of operative technique and results of LCU and IOC were analyzed by reviewing videotape recordings of each procedure. Laparoscopic cholecystectomy was achieved in 73 patients, with five requiring conversion to the open procedure. The success rate of IOC was 90% (64/71). Performance of IOC demanded more than twice the time needed for LCU. Eleven percent (8/71) of cholangiograms were abnormal, with a false-positive rate of 1% (1/71). Laparoscopic contact ultrasonography detected all four instances of unsuspected ductal stones but none of the three cases of anomalous biliary anatomy. Clinically relevant incidental findings were picked up by LCU in six patients. Laparoscopic contact ultrasonography proved to be extremely accurate in the detection of ductal stones but less reliable in the disclosure of anomalous biliary anatomy. The essential role of IOC in providing a clear spatial display of the biliary tract was confirmed. Since the two procedures are complementary, their combined use is advisable in difficult LC to avoid retained common bile duct stones and prevent iatrogenic complications.

Characteristics of biliary tract complications during laparoscopic cholecystectomy: A multi-institutional study

We collected the records of 81 patients with biliary tract injuries occurring during laparoscopic cholecystectomy (LC) who were referred to 3 referral centers during a 33-month (May 1990 to March 1993) period. All records were reviewed to provide data concerning the anatomy of the lesion induced, method of injury, timing of injury detection, role of intraoperative cholangiography (IOC), methods of treatment, and outcome of these injuries. Injuries were classified by our own method as follows: (1) cystic duct leaks (n = 15), (2) bile leaks and/or ductal strictures (n = 27), and (3) ductal transections or excisions (n = 39). Peak occurrence by quarter of the year was 4th quarter, 1990 (Lahey), and 3rd quarter, 1991 (Mason), and 1st quarter, 1992 (Mayo). The majority (62%) of the injuries were recognized after LC. At the time of LC, 31 of 81 (38%) injuries were recognized and converted to open procedures. Data regarding IOC were available in 63 of 81 (78%) cases. In patients in whom IOC was not performed, 14 of 38 (37%) operations were converted; if an IOC was obtained and interpreted correctly, 13 of 21 (62%) operations were converted. Primary repair was attempted in 11 leaks and/or strictures, but 36% required additional treatment. Primary repair was used in six transections or excisions, and 17% have required further intervention. In patients who had biliary-enteric bypass (BEB) performed outside (17) versus at the referral institution (29), 94% (16 patients) versus 0%, respectively, required additional operative (e.g., revision of a hepaticojejunostomy) or nonoperative (e.g., radiologic or endoscopic stenting or balloon dilation) procedures. When used as initial therapy or after a primary ductal repair, stents (with or without balloon dilation) resolved 100% of simple cystic duct leaks and 91% of leaks and/or strictures. In conclusion, the peak incidence of LC-related biliary injuries appears to have passed. A completed and correctly interpreted IOC increases the chance of detection of biliary injuries intraoperatively and should assist surgeons who use routine IOC. Nonsurgical techniques allow treatment of most simple cystic duct leaks, major ductal leaks and/or strictures, and postoperative BEB strictures, although followup is limited. The poor results of pre-referral BEB is not surprising since all of these patients were selected for referral because their treatments had not been successful.

Routine cholangiography is not warranted during laparoscopic cholecystectomy.

The role of intraoperative cholangiography during laparoscopic cholecystectomy was prospectively evaluated in 514 patients undergoing laparoscopic cholecystectomy. Before surgery, all patients were assigned to one of three groups depending on the likelihood of their having common bile duct stones. Stratification was based on objective historical, laboratory, or radiologic criteria. In 453 patients deemed unlikely to have stones, laparoscopic cholecystectomy was performed without cholangiography. Of these patients, four had retained stones (0.9%). In 25 patients likely to have stones, preoperative endoscopic retrograde cholangiopancreatography identified stones in six patients (24%). In 36 patients whose likelihood of having stones was deemed indeterminate, intraoperative cholangiography was performed at laparoscopic cholecystectomy. A common bile duct stone was identified in one patient (2.8%). One common bile duct injury occurred in the group deemed unlikely to have stones, and this injury would not have been prevented by intraoperative cholangiography. We conclude that preoperative assessment will identify common bile duct stones and that routine cholangiography is not warranted. Meticulous dissection of the cystic duct at its origin at the infundibulum will prevent common bile duct injury.

Biliary Ductal Anatomy and Anomalies: The Role of Intraoperative Cholangiography During Laparoscopic Cholecystectomy

Biliary ductal anomalies of surgical importance can occur in 10% of patients. The short cystic duct draining into the common bile or right hepatic duct and the extreme proximity of the common bile duct in case of spiral or posterior entry of the cystic duct--if not recognized in time--can result in ductal injuries. The new mobile, digitized fluoroscopic units provide a vastly improved image within minutes. In case of an inadvertent ductal injury (extravasation, no contrast material visible in the proximal ductal system) the surgeon can immediately repair the injury. Routine intraoperative cholangiography is strongly recommended during laparoscopic cholecystectomies.