is cannulated to a variable depth, and the diathermy wire is oriented away from the pancreatic ..... Breslow NE, Day NE. Statistical Methods in Cancer Research,.
Surgical Versus Endoscopic Management of Common Bile Duct Stones
B. M. MILLER, M.D., R. A. KOZAREK, M.D., J. A. RYAN, JR., M.D., T. J. BALL, M.D., and L. WILLIAM TRAVERSO, M.D.
The charts of all patients with common bile duct (CBD) stones admitted to Virginia Mason Medical Center between January 1, 1981 and July 31, 1986 were reviewed to define current methods of management and results of operative versus endoscopic therapy. Two hundred thirty-seven patients with CBD stones were treated. One hundred thirty patients had intact gallbladders. Of these patients, 76 (59%) underwent cholecystectomy and common bile duct exploration (CBDE) while 54 (41%) underwent endoscopic papillotomy (EP) only. Of the 107 patients admitted with recurrent stones after cholecystectomy, all but five were treated with EP. The overall mortality rate was 3.0%. Complications, success, and death rates were all similar for CBDE and EP, but the complications of EP were often serious and directly related to the procedure (GI hemorrhage, 6; duodenal perforation, 5; biliary sepsis, 4; pancreatitis, 1). Patients undergoing EP required significantly shorter hospitalization than those undergoing CBDE. Multivariate analysis showed that age greater than 70 years, technical failure, and complications increased the risk of death, regardless of procedure performed. Twenty-one per cent of those undergoing EP with gallbladders intact eventually required cholecystectomy. The conclusion is that the results of EP and CBDE are similar, and the use of EP has not reduced the mortality rates of this disease. ARL LANGENBUCH
performed the first chole-
cystectomy in 1882,' and for the first 90 years thereafter, operation formed the mainstay of
therapy for benign biliary tract disease. In the early 1 970s, however, techniques were developed in the fields of radiology and gastroenterology that would provide alternative therapeutic options and radically change management of biliary lithiasis. For example, in 1973 Burhenne reported fluoroscopically guided basket retrieval of common bile duct (CBD) stones via the T tube tract.
2
In
1974 Claasen and
Demling from
Germany'
Reprint requests and correspondence: Bonnie M. Miller, M.D., 2201 Murphy Avenue, Suite 410, Nashville, TN 37203. Submitted for publication: July 27, 1987.
From the Departments of Surgery and Gastroenterology, Virginia Mason Medical Center, Seattle, Washington
and Kawai from Japan4 independently described endoscopic papillotomy (EP). EP is performed using a lateral viewing duodenoscope. Vater's papilla is cannulated first with a diagnostic catheter, and a cholangiogram confirms the presence of stones and defines their size and location. The diagnostic catheter is then replaced with a papillotome, a diathermy wire attached to a teflon catheter. The papilla is cannulated to a variable depth, and the diathermy wire is oriented away from the pancreatic sphincter. An electrical current is passed down the wire, creating a to I1/2-cm incision, depending on the length of the sphincter and the size of the stones. The stones may be immediately retrieved with a Dormia basket or they may be allowed to pass spontaneously. A nasobiliary drainage catheter may be placed to prevent cholangitis if complete stone evacuation has not been accom1-
plished.5'6
Initially, EP was reserved for frail patients at high risk for operation with retained or recurrent CBD stones. Early reports documented mortality rates of 1-2%4 and major morbidity rates (pancreatitis, bleeding, and duodenal perforation) of 7-10%.7-9 These figures compared favorably with historical surgical controls from the 1950s and 1960s when the mortality rate after operative common bile duct exploration (CBDE) was at least 51%.IO,1 Considering this comparison and the greater patient satisfaction, EP rapidly gained wide acceptance and its applications broadened. In centers where skilled endoscopists practice, EP has become the procedure of choice for recurrent stones after cholecystectomy.'2,13 In addition, it is being used with increasing frequency in
135
i36
GB in
GB out
Operation
Group I 76
Group III
Endoscopy
Group 1l
Group IV 102
54
5
FIG. 1. Division ofpatients into four groups based on the presence of a gallbladder at the time of admission and initial procedure performed. Number of patients in each group is given in parentheses.
patients with intact gallbladders and
common
duct
stones. 4
The following report was undertaken to define the impact of EP on management of choledocholithiasis at a multispecialty referral center. Specifically, we wished to
analyze how patients are initially treated, what the current results of EP and CBDE are, and whether EP has reduced the overall mortality rate of patients with CBD stones.
The Virginia Mason Medical Center (VMMC) is a multispecialty clinic located in Seattle, WA, which draws referrals from the Pacific Northwest and Alaska.
140, 120-
A computer list was generated of all patients admitted between January 1, 1981 and July 31, 1986 with the diagnosis of choledocholithiasis. The charts of these patients were screened, and only those with CBD stones documented unequivocally by retrieval or cholangiogram were included in this analysis. Two hundred thirty seven patients had common bile duct stones during this study period. The charts of these patients were reviewed for the following data: previous cholecystectomy, procedures performed, age, year of admission, comorbid illness, acute presentation, complications, death, and technical success of procedure. In addition, patients who underwent EP without prior cholecystectomy were interviewed by telephone regarding recurrence of stones and need for subsequent procedures. The entire population (N = 237) was divided into four groups based on two factors: the presence of a gallbladder at the time of admission and the initial procedure attempted at VMMC (Fig. 1). Patients in group I (N = 76) had intact gallbladders and underwent cholecystectomy and CBDE with or without a biliary enteric drainage procedure. Group II patients (N = 54) also had intact gallbladders, but underwent EP only as the initial procedure. Group III patients (N = 5) had undergone prior cholecystectomy and were treated with CBDE, while those in group IV (N = 102) with prior cholecystectomy underwent EP.
Statistical Analysis
Patients and Methods
EP OR
co80-
Q. %4-600
65
Ann. Surg. - February 1988
MILLER AND OTHERS
40
The BMDP statistical package program was used for statistical analyses.'5 Continuous variables were analyzed by analysis of variance (ANOVA).16 A one-way ANOVA was performed to test the equality of means between two groups. This program also tests the equality of variances between the two groups (Levene's test for equal variances, a robust test computed on the absolute values of the deviations from the means).'7 Two additional oneway ANOVA statistics are also computed. Neither of these assumes the equality of variances in each group, which are: (1) the Welch statistic and (2) the BrownForsythe statistic."8 These tests were used when the variances were found to be unequal between the two groups. For multivariate analysis, Cox's logistic regression method was employed. In this model:
[V log P/1-P =
FIG. 2. Type of procedure initially performed in patients with and without gailbladders.
=
A + BIXi + B2X2 + B3X3
.
.
.
where A represents the log odds of disease risk for a person with a standard (X = 0) set of regression vari-
VOL. 207 . NO. 2
MANAGEMENT OF COMMON DUCT STONES
60-
137
30-
27
53
506
a
........ 39 ..............
40-
.)
...........
...........
.¢n00BB,c 33
33
31
30-
6 20-
LE
z
20-
~
co
~
1982
~ ~ ~
.......
1985.
1984....
z°~10-
roup....
.............
198
..roup.IV
1983
_ ~Group
E///Group [I
~ ~ .. ~~ ~~ ~~ ~ .......
..~~~~~~~~~~~~~~:9.:. :...8 .: ...........~~~~~~~~~~~~~~*:::9*9:::..@
10-
O-1 1981
~
III
Group IV
IGroup 11
FIG. 3. Total number of patients admitted each year with CBD stones, and their distribution into the four treatment groups.
[II
Group I IGroup 11
FIG. 4. The total number of patients over 70 years admitted each year with CBD stones is depicted. The patients are divided into treatment groups.
ables, while exp (Bk) is the fraction by which this risk is increased (or decreased) for every unit change in Xk.'9 Results Of the 237 patients, 130 had intact gallbladders (groups I and II) and 107 had retained or recurrent stones after cholecystectomy (groups III and IV). Of those with intact gallbladders, 76 underwent cholecystectomy and CBDE (59%) while 54 underwent EP (41%). Of the 107 patients who had previously undergone cholecystectomy, all but five had EP attempted as the initial procedure (Fig. 2). The number of patients with CBD stones increased during the last 3 years of the study (Fig. 3). The number of patients undergoing EP with gallbladders intact also rose during each suiccessive year of the study, but this was in proportion to the overall increase in patients with CBD stones. The only year in which the majority of patients underwent operation was 1981 (20 out of 33). Each year thereafter, the large majority of patients underwent papillotomy. The transition from CBDE to EP became even more apparent when examining only those patients over 70 years of age. Although the number of patients admitted per year remained stable in this age group, the number admitted for CBDE dropped sharply after 1981 (Fig. 4). For example, 12 of the 28 patients in group I who were over 70 years of age underwent operation in 1981; the remaining 16 operations were distributed fairly evenly over the next four years. The number of patients in group II over 70 years of age increased slightly over the study period, so that during the 51/2 years of this review,
the majority of patients over 70 with intact gallbladders underwent EP as opposed to CBDE (38 vs. 28). Thirtyfive of the 38 patients who underwent EP in group II were referred directly to gastroenterologists and had no surgical consultation prior to the procedure. Table 1 characterizes the four groups according to age, number of comorbid illnesses, and percentage of patients presenting with acute biliary tract disease. For each patient, the number of comorbid illnesses was determined, and the number listed in Table 1 represents the arithmetic mean for each group. The number listed under acute illness represents the percentage of each group that presented with either acute cholecystitis, cholangitis, or pancreatitis. The mean age of patients in group I was significantly less than that of groups II and IV (p < 0.05). There were no differences, however, in the mean number of comorbid illnesses per group or the fraction that presented acutely ill. Again, examining only patients in groups I and II over 70 years of age (Table 2), we found that those undergoing CBDE were still younger than those undergoing EP (p < 0.05). These groups were also similar with regard to TABLE 1. Group Characteristics
Age (yr) (Mean)
Age (yr) (Range)
No. of Comorbid Illnesses (Mean)
Acutely Ill
Group I II III IV
58+2*
19-88 25-104 50-84 30-97
1.2±0.1
75 ± 2 68 ± 6 68 ± 1
40 35 20 23
*
Group I vs. II and I vs. IV, p < 0.05.
1.7 ± 0.1 1.0 ± 0.8 1.6 ± 0.1
(%)
TABLE 4. Complication Rate
TABLE 2. Group Characteristics: Age > 70 Years with Intact Gallbladder Group
Age (yr) (Mean)
Age (yr) (Range)
No. of Comorbid Illnesses (Mean)
Acutely Ill (%)
I II
75 ± 1* 84 ± 1
70-89 70-104
1.5 ± 0.2 1.6 ± 0.2
36 42
*
Ann. Surg. February 1988
MILLER AND OTHERS
138
Group I vs.
Group (N)
Complications (%)
1(76) 11(54)
11(14) 5 (9) 2 (40) 17 (16)
III (5) IV (102)
II, p < 0.05.
acute and chronic illnesses. Thus, EP was the preferred
method of treating elderly patients with intact gallbladders, regardless of underlying health. Length of hospitalization was greater for patients treated with CBDE than for those treated with EP (p < 0.05). Patients in group I were hospitalized 10.3 ± 0.6 days compared to 6.4 ± 0.8 for group II; group III patients spent 16.0 4.8 days in the hospital compared to 6.0 ± 0.6 for group IV. Technical success of the procedure was defined as clearance of all stQnes from the bile ducts. Retained stones constituted failure for the operative groups (groups I and III). Multiple endoscopic procedures were commonly necessary to achieve clearance in groups II and IV. Such cases were still considered technically successful if clearance was ultimately attained without need for operation. Table 3 lists the success rates for all groups. All five patients with retained stones after CBDE underwent percutaneous basket retrieval via the T tube tract without complication. Of the 23 patients who had unsuccessful attempts at EP, 18 underwent subsequent CBDE. Table 4 depicts the complication rates for each group, and Table 5 lists the complications according to procedure (EP vs. CBDE). While the overall group complication rates did not differ significantly, the nature of the complications seemed more serious in patients undergoing EP. Sixteen of the 22 complications occurring in groups II and IV were directly a result of EP. There were six episodes of gastrointestinal (GI) hemorrhage (2 to 12 U), five duodenal perforations, four instances of biliary sepsis, and one case of pancreatitis. Seven of these 16 TABLE 3. Technical Success Rate
Success
Group
N
Failures
I (CBDE) II (EP) III (CBDE) IV (EP)
76 54 5 102
4
6 1 17
Rate (%)
Subsequent Procedures (N)
95 89 80 85
Basket extraction (4) CBDE (3) Basket extraction (1) CBDE (15)
complications resulted in a need for operation (GI bleed, 3; duodenal perforation, 2; biliary sepsis, 2), which represented 4.7% of the total number of patients who underwent EP. In contrast to the EP complications, five of the 13 CBDE complications were directly a result of the procedure. Two of these complications (hemorrhage and pancreatitis) necessitated reoperation, representing 2.5% of all patients undergoing CBDE. Seven of the 237 admissions for choledocholithiasis ended in hospital death. These seven patients are characterized in Table 6. The youngest patient who died was 70 years old. Each patient's group assignment reflects the initial procedure performed at VMMC. Only one patient had CBDE as the initial procedure. Four of the seven patients eventually required both EP and CBDE. One patient had undergone cholecystectomy and CBDE elsewhere and was transferred ten days postoperatively for endoscopic retrieval of a retained stone. Three patients underwent EP, then subsequently required operation for continued symptoms, technical failure, or complications. Myocardial infarction and sepsis were the most frequent causes of death. The overall mortality rate was 3.0%, 5.8% for patients 70 years or older, and 0% for patients less than 70 (Table 7). Mortality rates were similar for all groups. Cox's logistic regression method indicated that three factors increased the risk of death: presence of complications, age of 70 years or older, and technical failure. The following factors did not independently increase the risk of mortality: number of comorbid illnesses, type of procedure initially attempted, and presentation with acute biliary tract conditions. Follow-up data were obtained for 34 of 48 patients (72%) who had successful EP with intact gallbladders. The mean length of follow-up was 28 months. Seven of these patients (21%) underwent subsequent cholecystectomy for either acute cholecystitis or chronic continued symptoms. One patient underwent laparotomy elsewhere and was found to have chronic pancreatitis. Her gallbladder was not removed. One patient had two separate episodes of CBD stones during the study period and was treated twice with EP. Another patient had her first EP in 1980 before the study period and had her second EP in 1984 for another episode of stones.
VOl. 207 * NO. 2
139
MANAGEMENT OF COMMON DUCT STONES TABLE 6. Characteristics of Patients Who Died
TABLE 5. Complications
Procedure-related Biliary sepsis 3 Pancreatitis 1 Hemobilia 1 Subtotal 5 (6%) Not procedure-related Respiratory 3 Urinary tract 3 Miscellaneous 2 Subtotal 8 (10%) Total 13 (16%)
Acutely
Groups II and IV (EP)
Patient No.
Age
Group
Procedures
Ill
GI hemorrhage 6 Duodenal perforation 5 Biliary sepsis 4 Pancreatitis 1 Subtotal 16 (10%)
1 2 3 4 5 6 7
83 93 89 75 74 70 87
I II IV II IV IV IV
CBDE EP EP EP, CBDE EP, CBDE EP, CBDE CBDE, EP
+ +
Groups I and III (CBDE)
Acute MI 2 Acture renal failure 1 Miscellaneous 3 Subtotal 6 (4%) Total 22 (14%)
Discussion In examining the recent management of choledocholithiasis at VMMC, we found that the overwhelming majority of patients with CBD stones after cholecystectomy were treated with EP. This was not surprising, in view of VMMC's regional reputation for skilled endoscopy and the current trend in both Europe and the United States to treat recurrent stones in this manner.8"12"13 During the past 51/2 years, however, 41% of all patients with gallbladders intact, and 58% of patients over 70 years of age with gallbladders intact, were initially treated with EP. While the patients who underwent EP were significantly older than those undergoing CBDE, they were similar with regard to both chronic comorbidity and the fraction that presented acutely ill. Thus, at our institution, EP has become the preferred method of treating elderly patients with CBD stones and gallbladders intact, regardless of underlying health. This unexpected preference reflects the current thinking of general physicians and gastroenterologists since 92% of these elderly patients underwent EP without prior surgical consultation. Can this radical shift in management be justified on the basis of improved results? The technical success rates of EP and CBDE were similar, and compared favorably with those reported by other institutions.'4'20'22 While the overall complication rates were also similar, we found that the actual complications of EP were more frequently life-threatening and were most often a direct result ofthe procedure (GI hemorrhage, duodenal perforation, biliary sepsis). Nearly half of these EP-related complications necessitated a subsequent, often urgent operation. The overall complication rate of 14% associated with EP may seem high when compared to other reports. Most studies on EP have reported only the procedure-related complications,8 9"14'23 thus lowering the
-
-
Cause of Death Sepsis Sepsis Sepsis MI GI bleed Sepsis MI
published rates and making comparison to surgical series somewhat imbalanced. In addition, one of these reports'4 noted a complication rate of 13% when cases were reviewed by an independent observer, as in the current study. Mortality rates of all groups were also similar and may seem high for EP and low for CBDE. This may be explained by two factors. First, four of the seven patients who died required both EP and CBDE, making it difficult to attribute the death to one procedure or the other. Second, the patients who underwent EP were older than those who underwent CBDE, making comparison between the groups less valid. Several series have recently been published that examine the results of CBDE before EP was widely utilized, and thus before it exerted any such selection bias. Pitt et al.24 reported no deaths in 47 patients undergoing cholecystectomy and CBDE; Broughan et al.'3 reported a 0.8% mortality rate for operation on patients with recurrent stones only; McSherry and Glenn25 reviewing 30 years experience, reported a mortality rate of 3.2% for all patients undergoing CBDE. Others document similar mortality rates.26 Our mortality rate of 3.0% is within this range. These data suggest that CBDE can be performed with morbidity and mortality rates at least equal to those currently observed for EP, and that the widespread use of EP at our institution has not reduced the overall mortality of CBD stones. Recognizing the limitations of retrospective studies, we subjected our data to multivariate analysis, and
TABLE 7. 30-Day Mortality Rates
Group
Deaths (%)
Deaths (%) Patients >70 Years
I II III IV
1 (1.3) 2 (3.7) 0 4 (3.9) 3.0
1 (3.6) 2 (5.3) 0 4 (7.5) 5.8
Total
140
MILLER AND OTHERS
found that, indeed, type ofprocedure performed was not an important determinant of mortality rate. Rather, age greater than 70 years, technical failure, and presence of complications significantly increased the risk of death. Although four of the seven patients who died eventually required both EP and CBDE, the need for a second procedure did not independently increase risk when adjusted for technical failure. Numerous studies have documented age as a risk factor for benign biliary tract procedures.'0'24'25'27 This has generally been attributed to the greater proportion of elderly patients who require emergent procedures and to concurrent chronic illness.26'28 Our data, however, do not support these notions. We did not find that acute cholecystitis, pancreatitis, or cholangitis negatively affected survival. In addition, the risk of mortality did not increase in proportion to the number of comorbid conditions, and age remained a significant risk factor even when adjusted for chronic disease. Thus, the elderly patient remains fragile with regard to biliary tract procedures, regardless of underlying health. Whichever procedure is chosen should be performed successfully and without complication. Of the patients undergoing EP with intact gallbladders, 21% required subsequent cholecystectomy. The cholecystectomy rates reported by other institutions range from 8.6%-28%. 12329,30 Siegel et al.Y0 recently reported that 109 of 1272 patients (9%) who underwent EP with gallbladders intact developed acute cholecystitis within 10 days of the procedure. The majority of these patients responded to medical management, but 25 required operation. Eight of the patients who required emergent operation died. This suggests that acute cholecystitis should also be considered a frequent and potentially fatal complication of EP in patients with intact gallbladders. Endoscopists have reasoned that EP spares the need for CBDE even if cholecystectomy becomes necessary, and thus should reduce the morbidity and mortality rates of operation. Neoptolemos et al.3' recently tested this theory with a prospective study. Patients were randomly assigned to undergo either cholecystectomy with CBDE or EP followed by cholecystectomy 3 days later. The complication and death rates were nearly doubled for the latter group, although the study was halted before the differences became statistically significant. This implies that the risks for the two procedures (EP and cholecystectomy) are additive and that the risk of EP in these patients was at least as great as the risk of CBDE. In 1980 McSherry and Glenn stated that "the mortality rates of secondary choledochotomy and endoscopic papillotomy are comparable and that . . . acceptance of [EP] on the basis of less mortality and morbidity in
Ann. Surg. February 1988
comparison to surgical therapy is unjustified."25 Our data confirm this opinion. We believe, however, that EP should remain the procedure of choice for CBD stones after cholecystectomy. While use of EP is not justified on the basis of improved results, it does permit less inhospital time, which implies greater cost-effectiveness and patient satisfaction. The role of EP alone as the initial therapy for patients with intact gallbladders, however, is not yet clearly established. Although cholecystectomy may be avoided in 75-80% of these patients, this benefit must be weighed against the excessive mortality risk that accompanies complicated unsuccessful procedures ending in emergent operation. Studies suggest that certain subsets of patients with intact gallbladders might benefit from early EP, such as those with cholangitis32 or pancreatitis.33 These groups remain to be defined by controlled, prospective studies. Acknowledgments We wish to acknowledge Bette Glass for her fine secretarial skills and Gloria Bailey, Ph.D., for performing the statistical analysis.
References 1. Traverso LW. Carl Langenbuch and the first cholecystectomy. Am J Surg 1976; 132:81-82. 2. Burhenne HJ. Nonoperative retained biliary stone extraction: a new roentgenological technique. Am J Radiol 1973; 117:388399. 3. Classen M, Demling L. Endoscopische sphinckterotomie der papilla vateri. Dtsch Med Wochenschr 1974; 99:496-497. 4. Kawai K, Akasaka Y, Murakami M, et al. Endoscopic sphincterotomy of the ampulla of vater. Gastrointest Endosc 1974; 20:148-151. 5. Cotton PB, Mason RR, Burney PJ. Transnasal bile duct catheterization after endoscopic sphincterotomy. A method of biliary drainage, perfusion, and sequential cholangiography. Gut
1979; 20:285-287. 6. Alberti-Flor JJ, Dunn D. Intracholedochal irrigation with saline through a nasobiliary catheter: an adjunct to endoscopic sphincterotomy in the treatment of large stones in the common bile duct. South Med J 1985; 78:1337-1340. 7. Claasen M, Safrany L. Endoscopic papillotomy and removal of gallstones. Br Med J 1975; 4:37 1. 8. Cotton PB, Vallon G. British experience with duodenoscopic sphincterotomy for removal ofbile duct stones. Br J Surg 1981; 68:373-375. 9. Neuhaus B, Safrany L. Complications of endoscopic sphincterotomy and their treatment. Endoscopy 1981; 13:197-199. 10. Glenn F, Hays DM. The age factor in the mortality rate of patients undergoing surgery of the biliary tract. Surg Gynecol Obstet 1955; 100:11-18. 11. Haff RC, Butcher HR, Ballinger WF. Biliary tract operation. a review of 1000 patients. Arch Surg 1969; 98:428-434. 12. Allen B, Shapiro H, Way LW. Management of recurrent and residual common duct stones. Am J Surg 1981; 142:41-47. 13. Broughan TA, Sivak M, Hermann RE. The management of retained and recurrent bile duct stones. Surgery 1985; 98:746751. 14. Neoptolemos JP, Carr-Locke DL, Fraser I, Fossard DP. The management of common duct calculi by endoscopic sphinctero-
Vol. 207 * No. 2
15. 16. 17.
18.
MANAGEMENT OF COMMON DUCT STONES
tomy in patients with gailbladders in situ. Br J Surg 1984; 71:69-71. BMDP. The BMDP statistical software package for the IBM PC. Los Angeles, BMDP Statistical Software Inc, 1985. WJ Dixon (ed). BMDP Statistical Software. Berkeley, CA: University of California Press, 1985; 105-115. Brown MB, Forsythe AB. Robust tests for the equality of variances. J Am Statist Assoc 1974; 69:364-367. Brown MB, Forsythe AB. The small sample behavior of some statistics which test the equality of several means. Technome-
trics 1974; 16:129-132. 19. Breslow NE, Day NE. Statistical Methods in Cancer Research, Vol. 1. The Analysis of Case-Control Studies. Lyon, France: IARC Scientific Publications. No 32. International Agency for Research on Cancer. 1980. 20. Escourroy J, Cordova JA, Lazorthes F, et al. Early and late complications after endoscopic sphincterotomy for biliary lithiasis with and without the gallbladder in situ. Gut 1984; 25:598602. 21. Cotton PB. Endoscopic management of bile duct stones (apples and oranges). Gut 1984; 25:587-597. 22. Way LW, Admirand WH, Dunphy JE. Management of choledocholithiasis. Ann Surg 1972; 176:347-359. 23. Kuilman E, Borch K, Tarpila E, Liedberg G. Endoscopic sphincterotomy in the treatment of choledocholithiasis and ampullar stenosis. Acta Chir Scand 1985; 151:619-624. 24. Pitt HA, Cameron JL, Postier RG, Gadacz TR. Factors affecting mortality in biliary tract surgery. Am J Surg 1981; 141:66-72.
141
25. McSherry CK, Glenn F. The incidence and causes ofdeath following surgery for nonmalignant biliary tract disease. Ann Surg 1980; 191:271-275. 26. Crumplin MKH, Jenkinson LR, Kassab JY, et al. Management of gallstones in a district general hospital. Br J Surg 1985; 72:428-432. 27. Vellacott KD, Powell PH. Exploration ofthe common bile duct: a comparative study. Br J Surg 1979; 66:389-391. 28. Sullivan DM, Hood TR, Griffen WO. Biliary tract surgery in the elderly. Am J Surg 1982; 143:218-220. 29. Solhaug JH, Fokstuen 0, Rosseland A, Rydberg B. Endoscopic papillotomy in patients with gallbladder in situ. Acta Chir Scand 1984; 150:475-478. 30. Siegel JH, Safrany L, Pullano W, Cooperman A. The significance of duodenoscopic sphincterotomy in patients with gallbladders in situ: 11 year follow-up of 1272 patients, abstract. Chicago, American Society for Gastrointestinal Endoscopy, 1987. 31. Neoptolemos JP, Carr-Locke DL, Fossard DL. Prospective randomized study of preoperative endoscopic sphincterotomy versus surgery alone for common bile duct stones. Br Med J 1987; 294:470-474. 32. Leese T, Neoptolemos JP, Baker AR, Caff-Locke DL. Management of acute cholangitis and the impact of endoscopic sphincterotomy. Br J Surg 1986; 73:988-992. 33. Neoptolemos JP, London N, Slater ND, et al. A prospective study of ERCP ad endoscopic sphincterotomy in the diagnosis and treatment of gallstone acute pancreatitis. Arch Surg 1986; 121:697-702.
