Surgical Endoscopy
Surg Endosc (1990) 4:20-22
© Springer-Verlag 1990
Large-bile-duct stones - extracorporeal piezoelectric lithotripsy as adjuvant measure for endoscopic basket extraction E. J. Kohlberger, J. Riidecke, R. Salm, and J. Waninger Abteilung Allgemeine Chirurgie mit Poliklinik, Chirurgische Universit~itsklinik,Hugstetterstrasse 55, D-7800 Freiburg i. Br., Federal Republic of Germany
Summary. Extracorporeal piezoelectric lithotripsy (EPL) was performed in 12 patients with large-bile-duct stones and intrahepatic stones. The Piezolith 2300 lithotripter (Wolf, Knittlingen, FRG) was used in all patients in w h o m routine endoscopic approaches for removal of the calculi had failed or were considered inappropriate because of large stone size or difficult localization. In 9 of the 12 patients the stones were fragmented. Complete stone clearance from the bile ducts was obtained in 8 of 10 patients by E P L alone or combined with one of the following: endoscopic extraction, mechanical lithotripsy or installation of solvents. Adjuvant E P L in conjunction with endoscopic therapy increased the success rate of nonsurgical treatment for bile duct stones from 73% to 95%. No clinically significant side effects or complications were noted.
Key words: Large-bile-duct stones - Endoscopic therapy - Adjuvant extracorporeal piezoelectric lithotripsy (EPL)
Bile-duct stones after cholecystectomy or in high-risk patients can be r e m o v e d by endoscopic basket extraction through a T-tube track or via an endoscopic sphincterotomy. These techniques m a y fail if stones are large (>2 cm) or unfavourably localized, e.g. in ma intrahepatic duct. Initial results with extracorporeal piezoelectric lithotripsy (EPL) in gallbladder calculi encouraged us to carry out a prospective trial of this procedure as an adjuvant measure in the m a n a g e m e n t of problematic bile-duct stones. The aim of the study was to assess the success, complications, and side-effects of E P L in the m a n a g e m e n t of choledocholithiasis. In this study E P L was used exclusively when endoscopic extraction via an endoscopic sphincterotomy seemed impossible or had failed.
whose ages ranged from 53-91 years (mean 74.5 years). Ten patients with large-bilde-duct calculi (> 1.8 cm) and two patients with intrahepatic stones received EPL as an adjuvant procedure after sphincterotomy. The indication for EPL in all patients "was the failure of or anticipated difficulty with basket extraction. In all patients a nasobiliary tube had been placed after diagnostic endoscopic retrograde cholangiopancreaticography and sphincterotomy. The pre-EPL work-up included a history, physical examination, chest X-ray, electrocardiogram, ultrasonography, cholangiography and blood tests, including coagulation parameters. EPL was performed in the prone position and stone focusing monitored continuously by ultrasound (Fig. 1). No anaesthesia or analgesia was used. The success of EPL and endoscopic extraction was documented by cholangiography via sphincterotomy or a nasobiliary tube.
Results Bile-duct stones were successfully extracted in 25 patients (67.5%) by primary endoscopic therapy. Following endoscopic sphincterotomy, 12 symptomatic patients with problematic calculi were treated using E P L (Table 2). The success rate of ultrasonographic focusing of bile-duct calculi was 83% (10/12). Ultrasonographic localisation of extrahepatic stones failed in 2 patients. The stones were extracted endoscopically in I patient and cleared by chemical dissolution and mechanical lithotripsy in the other. The success rate of stone fragmentation or reduction in stone size was 75% (9/12). Fragmentation required one or two
Patients and methods Between March 1988 and April 1989, 37 patients with bile-duct stones post-cholecystectomy were treated endoscopically. In 12 of these patients, endoscopic sphincterotomy ar/d basket extraction failed to remove the stones (Table 1). In this group there were 6 men and 6 women Offprint requests to: E. J. Kohlberger
Fig. 1. Extracorporeal piezoelectric lithotripsy (EPL) of bile duct and intrahepatic stones. The patient is partially immersed in the water bath in the prone position. Visualization of the stone is achieved by ultrasonography, which allows continuous targeting of the stone in the shock-wave focus
21
Fig. 2 a - d . A 78-year-old woman with jaundice. She had had a cholecystectomy 1 year earlier, a Cholangiography via sphincterotomy shows a bile-duct stone larger than 20 ram. b Ultrasound in prone position shows a dilated bile duct. The stone (S) and its shadow (diagonal dotted line ) are adjacent to the shock wave focus (cross marker). c Cholangiogram via nasobiliary tube after EPL demonstrating stone fragments, d Successful stone extraction after EPL documented by cholangiography via nasobiliary tube
Table 1. Characteristics of patients (n = 12) and bile-duct stones Patients
Table 2. Results with EPL, as adjuvant measure to endoscopic therapy of large bile duct and intrahepatic stones. Endoscopic extraction and mechanical lithotripsy were successfully performed in most patients. One patient needed systemic chemolitholysis with urso- and chenodesoxycholacid. Two patients required surgery and solvents were applied to the bile duct in one patient
Stones No.
No.
Age (years)
Sex
Size
Number
Localization
1 2 3 4 5 6 7 8 9 10 11 12
82 82 78 53 91 66 76 67 82 65 78 75
F F F M M M F M M F F M
25 mm -30 mm 25 mm - 5 mm -30 mm 18 mm -25 mm 20 mm 30 mm 28 mm 12 mm -20 mm
Solitary Multiple Solitary Multiple Multiple Solitary Multiple Solitary Solitary Solitary Solitary Multiple
Bile duct Bile duct Bile duct Intrahepatic Bile duct Bile duct Bile duct Bile duct Bile duct Bile duct Intrahepatic Bile duct
Localization
Shock waves/ intensity
Disintegration
Adjuvant measures
1 2 3 4 5 6 7 8
+ + + + + + -
1500/3 3000/3 3200/3 3600/3 2000/3 -/500/4 -/-
+ + + + + -
9 10 11 12
+ + + +
3500/3 4000/3 2500/3 1500/3
+ _+ + ±
Operation Mechanical lithotripsy Endoscopical extraction Systemical chemolysis Endoscopical extraction Endoscopical extraction Mechanical lithotripsy Chemical litholysis; mechanical lithotripsy Endoscopical extraction Operation Endoscopical extraction
22 sessions and 5 0 0 - 4 0 0 0 shock waves (median: 2530) were administered. Two patients with bile-duct stones required surgical removal of the stones. Successful fragmentation and passage of fragments were achieved in 8 of the 10 remaining patients treated with EPL and additional procedures. Endoscopic basket extraction was required in 4 patients (Fig. 2), while in 2 patients the stones were removed by mechanical lithotripsy. Additional systemic chemolitholysis was successful in 1 patient with intrahepatic stone fragments. The stones passed spontaneously in a single patient. Therefore, complete stone clearance from the bile ducts was obtained in 27 of 37 patients (73%) after endoscopic therapy alone and in 35 of 37 patients (95%) with adjuvant EPL alone or in combination with endoscopic extraction or dissolution of the fragments. No clinically significant sideeffects or complications of shock-wave lithotripsy were noted. Bruising of the skin was seen in 6 patients.
Discussion Endoscopic techniques have resulted in improved clearance of bile-duct stones, but they fail in about 10% of patients [2, 8]. These difficult cases can be treated by mechanical lithotripsy with a Dormia basket, laser lithotripsy, direct electrohydraulic lithotripsy or instillation of solvents [6, 7, 9 - 1 1 , 13, 14]. These procedures all have side-effects and complications, and they are not universally successful and may be time-consuming. Recently, extracorporeal shock-wave therapy without direct contact with the stone has become available for the non-surgical management of bile-duct stones [1, 4, 1 0 12]. This therapy is effective in conjunction with endoscopic treatment and had no complications in our experience. Adverse effects, mostly mild, were documented in another multicentre trial in 36% of patients with a mortality of 0.9% [11]. These results compare favourably with the results given in the literature for operative biliary surgery in high-risk groups [3, 5, 15]. Our rate of successful stone fragmentation (75%) is similar to that reported in the literature. However, our rate of spontaneous passage of stone fragments following EPL is much lower than that found by Fried and colleagues [4]. This is probably related to our criteria for patient selection. Whereas some authors performed shock-wave lithotripsy as a primary therapy, we and other lithotripsy groups have reserved it for cases in whom endoscopic basket extraction had failed or seemed inappropriate [1, 10-12]. Thus, spontaneous passage of fragments was noted in only one patient with intrahepatic stone fragments in our study. The optimal number of shock waves to achieve stone fragmentation has not yet been established. We used between 500 and 4000 shocks with satisfactory fragmentation in 8 of 10 patients. This is within the range of current practice [ 1, 4, 12]. Reports on extracorporeal shock-wave lithotripsy of bile duct stones in the literature are based on experience with other systems, which are not similar to EPL [1, 4, 11]. Thus, visualization of stones was not a problem in these reports, as it was achieved by injection of contrast medium
into the biliary tree via a nasobiliary tube. However, we failed to localize bile-duct stones in 2/12 patients using ultrasound for stone visualization. Failure of ultrasonographic stone focusing occurs in 17% of patients and is a problem with piezoelectric and sonographic lithotripsy technique. X-ray localization may raise the success rate of stone visualization, but the fact that some stones were not demonstrable behind certain gas-filled bowel areas in our patients could indicate that lithotripsy using other systems failed in certain cases of bile-duct stones as well. In our opinion, endoscopic procedures represent the gold standard of non-surgical treatment of bile-duct stones. EPL as an additional measure to endoscopic techniques can increase the rate of stone clearance. Further studies are necessary to evaluate this technique which, in contrast to other auxiliary procedures, requires no anaesthesia or analgesia.
References 1. Btihler H, Jaeger P, Ammann R, Hauri D, Kn6nagel H, Mtinch R, Siegenthaler W (1988) Extracorporale Stogwellenlithotripsie (ESWL) zur Behandlung yon Gallengangssteinen. Schweiz Med Wochenschr 118:113-117 2. Cotton PB (1984) Endoscopic management of bile-duct stones (apples and oranges). Gut 25: 587-597 3. Doyle PY, Ward-McQuaid JN, McEwen Smith A (1982) The value of routine per-operative cholangiography - a report of 4000 cholecystectomies.Br J Surg 69:617 - 619 4. Fried LA, Lebrun GP, Norman RW, Fraser DB, Taylor MC, Roy PD, Marshall JC (1988) Extracorporeal shock-wave lithotripsy in the management of bile duct stones. AJR 151:923 -926 5. Glenn F (1975) Trends in surgical treatment of calculus disease of the biliary tract. Surg Gynecol Obstet 140: 877-884 6, Lux G, Ell CH, HochbergerJ, Mtiller D, Demling L (1986) The first successful endoscopic retrograde laser lithotripsy of common bile duct stones in man using a pulsed neodynium-YAGlaser. Endoscopy 18: 144-145 7. Neoptolemos JP, Hofmann AF, Moossa AR (1986) Chemical treatment of stones in the biliary tree. Br J Surg 73:515 -524 8. Riemann JF, Demling L (1983) Lithotripsy of bile duct stones. Endoscopy 15:191 - 196 9. Riemann JF, Seubert K, Demling L (1982) Clinical application of a new mechanical lithotriptor for smashing common bile duct stones. Endoscopy 14:226-230 10. Sauerbruch T, Holl J, Sackmann M (1987) Treatment of bile duct stones by extracorporeal shock waves. Semin Ultrasound CT MR 8: 155-161 11. SauerbruchT, Stem M, the Study Group for Shock-WaveLithotripsy of Bile Duct Stones (1989) Fragmentation of bile duct stones by extracorporeal shock-waves.A new approach to biliary calculi after failure of routine endoscopic measures. Gastroenterology96:146 152 12. Staritz M, Floth A, Rambow A, Wilbert D, Meyer zum Btischenfelde KH (1987) Behandlung groger Gallengangssteine dutch extrakorporale Stoi~wellenlithotripsie (ESL) mit einem Ger~t der zweiten Generation. Z Gastroentero125: 570- 576 13. Tanaka M, Yoshimoto H, Ikeda S, Matsumoto S, Xuan GR (1985) Two approachesfor electrohydraulic lithotripsy in the common bile duct. Surgery 98:313-318 14. Thistle JL, Carlson GL, Hofmann AF, LaRusso NF, MacCarty RL, Flynn GL, Higuchi WI, Babayan VK (1980) Monooctanoin, a dissolution agent for retained cholesterolbile duct stones: physicalproperties and clinical application. Gastroenterology78: 1016-1020 15. Vellacott KD, Powell PH (1979) Exploration of the common bile duct: a comparative study. Br J Surg 66:389-391
Surg Endosc (1990) 4:20-22
© Springer-Verlag 1990
Large-bile-duct stones - extracorporeal piezoelectric lithotripsy as adjuvant measure for endoscopic basket extraction E. J. Kohlberger, J. Riidecke, R. Salm, and J. Waninger Abteilung Allgemeine Chirurgie mit Poliklinik, Chirurgische Universit~itsklinik,Hugstetterstrasse 55, D-7800 Freiburg i. Br., Federal Republic of Germany
Summary. Extracorporeal piezoelectric lithotripsy (EPL) was performed in 12 patients with large-bile-duct stones and intrahepatic stones. The Piezolith 2300 lithotripter (Wolf, Knittlingen, FRG) was used in all patients in w h o m routine endoscopic approaches for removal of the calculi had failed or were considered inappropriate because of large stone size or difficult localization. In 9 of the 12 patients the stones were fragmented. Complete stone clearance from the bile ducts was obtained in 8 of 10 patients by E P L alone or combined with one of the following: endoscopic extraction, mechanical lithotripsy or installation of solvents. Adjuvant E P L in conjunction with endoscopic therapy increased the success rate of nonsurgical treatment for bile duct stones from 73% to 95%. No clinically significant side effects or complications were noted.
Key words: Large-bile-duct stones - Endoscopic therapy - Adjuvant extracorporeal piezoelectric lithotripsy (EPL)
Bile-duct stones after cholecystectomy or in high-risk patients can be r e m o v e d by endoscopic basket extraction through a T-tube track or via an endoscopic sphincterotomy. These techniques m a y fail if stones are large (>2 cm) or unfavourably localized, e.g. in ma intrahepatic duct. Initial results with extracorporeal piezoelectric lithotripsy (EPL) in gallbladder calculi encouraged us to carry out a prospective trial of this procedure as an adjuvant measure in the m a n a g e m e n t of problematic bile-duct stones. The aim of the study was to assess the success, complications, and side-effects of E P L in the m a n a g e m e n t of choledocholithiasis. In this study E P L was used exclusively when endoscopic extraction via an endoscopic sphincterotomy seemed impossible or had failed.
whose ages ranged from 53-91 years (mean 74.5 years). Ten patients with large-bilde-duct calculi (> 1.8 cm) and two patients with intrahepatic stones received EPL as an adjuvant procedure after sphincterotomy. The indication for EPL in all patients "was the failure of or anticipated difficulty with basket extraction. In all patients a nasobiliary tube had been placed after diagnostic endoscopic retrograde cholangiopancreaticography and sphincterotomy. The pre-EPL work-up included a history, physical examination, chest X-ray, electrocardiogram, ultrasonography, cholangiography and blood tests, including coagulation parameters. EPL was performed in the prone position and stone focusing monitored continuously by ultrasound (Fig. 1). No anaesthesia or analgesia was used. The success of EPL and endoscopic extraction was documented by cholangiography via sphincterotomy or a nasobiliary tube.
Results Bile-duct stones were successfully extracted in 25 patients (67.5%) by primary endoscopic therapy. Following endoscopic sphincterotomy, 12 symptomatic patients with problematic calculi were treated using E P L (Table 2). The success rate of ultrasonographic focusing of bile-duct calculi was 83% (10/12). Ultrasonographic localisation of extrahepatic stones failed in 2 patients. The stones were extracted endoscopically in I patient and cleared by chemical dissolution and mechanical lithotripsy in the other. The success rate of stone fragmentation or reduction in stone size was 75% (9/12). Fragmentation required one or two
Patients and methods Between March 1988 and April 1989, 37 patients with bile-duct stones post-cholecystectomy were treated endoscopically. In 12 of these patients, endoscopic sphincterotomy ar/d basket extraction failed to remove the stones (Table 1). In this group there were 6 men and 6 women Offprint requests to: E. J. Kohlberger
Fig. 1. Extracorporeal piezoelectric lithotripsy (EPL) of bile duct and intrahepatic stones. The patient is partially immersed in the water bath in the prone position. Visualization of the stone is achieved by ultrasonography, which allows continuous targeting of the stone in the shock-wave focus
21
Fig. 2 a - d . A 78-year-old woman with jaundice. She had had a cholecystectomy 1 year earlier, a Cholangiography via sphincterotomy shows a bile-duct stone larger than 20 ram. b Ultrasound in prone position shows a dilated bile duct. The stone (S) and its shadow (diagonal dotted line ) are adjacent to the shock wave focus (cross marker). c Cholangiogram via nasobiliary tube after EPL demonstrating stone fragments, d Successful stone extraction after EPL documented by cholangiography via nasobiliary tube
Table 1. Characteristics of patients (n = 12) and bile-duct stones Patients
Table 2. Results with EPL, as adjuvant measure to endoscopic therapy of large bile duct and intrahepatic stones. Endoscopic extraction and mechanical lithotripsy were successfully performed in most patients. One patient needed systemic chemolitholysis with urso- and chenodesoxycholacid. Two patients required surgery and solvents were applied to the bile duct in one patient
Stones No.
No.
Age (years)
Sex
Size
Number
Localization
1 2 3 4 5 6 7 8 9 10 11 12
82 82 78 53 91 66 76 67 82 65 78 75
F F F M M M F M M F F M
25 mm -30 mm 25 mm - 5 mm -30 mm 18 mm -25 mm 20 mm 30 mm 28 mm 12 mm -20 mm
Solitary Multiple Solitary Multiple Multiple Solitary Multiple Solitary Solitary Solitary Solitary Multiple
Bile duct Bile duct Bile duct Intrahepatic Bile duct Bile duct Bile duct Bile duct Bile duct Bile duct Intrahepatic Bile duct
Localization
Shock waves/ intensity
Disintegration
Adjuvant measures
1 2 3 4 5 6 7 8
+ + + + + + -
1500/3 3000/3 3200/3 3600/3 2000/3 -/500/4 -/-
+ + + + + -
9 10 11 12
+ + + +
3500/3 4000/3 2500/3 1500/3
+ _+ + ±
Operation Mechanical lithotripsy Endoscopical extraction Systemical chemolysis Endoscopical extraction Endoscopical extraction Mechanical lithotripsy Chemical litholysis; mechanical lithotripsy Endoscopical extraction Operation Endoscopical extraction
22 sessions and 5 0 0 - 4 0 0 0 shock waves (median: 2530) were administered. Two patients with bile-duct stones required surgical removal of the stones. Successful fragmentation and passage of fragments were achieved in 8 of the 10 remaining patients treated with EPL and additional procedures. Endoscopic basket extraction was required in 4 patients (Fig. 2), while in 2 patients the stones were removed by mechanical lithotripsy. Additional systemic chemolitholysis was successful in 1 patient with intrahepatic stone fragments. The stones passed spontaneously in a single patient. Therefore, complete stone clearance from the bile ducts was obtained in 27 of 37 patients (73%) after endoscopic therapy alone and in 35 of 37 patients (95%) with adjuvant EPL alone or in combination with endoscopic extraction or dissolution of the fragments. No clinically significant sideeffects or complications of shock-wave lithotripsy were noted. Bruising of the skin was seen in 6 patients.
Discussion Endoscopic techniques have resulted in improved clearance of bile-duct stones, but they fail in about 10% of patients [2, 8]. These difficult cases can be treated by mechanical lithotripsy with a Dormia basket, laser lithotripsy, direct electrohydraulic lithotripsy or instillation of solvents [6, 7, 9 - 1 1 , 13, 14]. These procedures all have side-effects and complications, and they are not universally successful and may be time-consuming. Recently, extracorporeal shock-wave therapy without direct contact with the stone has become available for the non-surgical management of bile-duct stones [1, 4, 1 0 12]. This therapy is effective in conjunction with endoscopic treatment and had no complications in our experience. Adverse effects, mostly mild, were documented in another multicentre trial in 36% of patients with a mortality of 0.9% [11]. These results compare favourably with the results given in the literature for operative biliary surgery in high-risk groups [3, 5, 15]. Our rate of successful stone fragmentation (75%) is similar to that reported in the literature. However, our rate of spontaneous passage of stone fragments following EPL is much lower than that found by Fried and colleagues [4]. This is probably related to our criteria for patient selection. Whereas some authors performed shock-wave lithotripsy as a primary therapy, we and other lithotripsy groups have reserved it for cases in whom endoscopic basket extraction had failed or seemed inappropriate [1, 10-12]. Thus, spontaneous passage of fragments was noted in only one patient with intrahepatic stone fragments in our study. The optimal number of shock waves to achieve stone fragmentation has not yet been established. We used between 500 and 4000 shocks with satisfactory fragmentation in 8 of 10 patients. This is within the range of current practice [ 1, 4, 12]. Reports on extracorporeal shock-wave lithotripsy of bile duct stones in the literature are based on experience with other systems, which are not similar to EPL [1, 4, 11]. Thus, visualization of stones was not a problem in these reports, as it was achieved by injection of contrast medium
into the biliary tree via a nasobiliary tube. However, we failed to localize bile-duct stones in 2/12 patients using ultrasound for stone visualization. Failure of ultrasonographic stone focusing occurs in 17% of patients and is a problem with piezoelectric and sonographic lithotripsy technique. X-ray localization may raise the success rate of stone visualization, but the fact that some stones were not demonstrable behind certain gas-filled bowel areas in our patients could indicate that lithotripsy using other systems failed in certain cases of bile-duct stones as well. In our opinion, endoscopic procedures represent the gold standard of non-surgical treatment of bile-duct stones. EPL as an additional measure to endoscopic techniques can increase the rate of stone clearance. Further studies are necessary to evaluate this technique which, in contrast to other auxiliary procedures, requires no anaesthesia or analgesia.
References 1. Btihler H, Jaeger P, Ammann R, Hauri D, Kn6nagel H, Mtinch R, Siegenthaler W (1988) Extracorporale Stogwellenlithotripsie (ESWL) zur Behandlung yon Gallengangssteinen. Schweiz Med Wochenschr 118:113-117 2. Cotton PB (1984) Endoscopic management of bile-duct stones (apples and oranges). Gut 25: 587-597 3. Doyle PY, Ward-McQuaid JN, McEwen Smith A (1982) The value of routine per-operative cholangiography - a report of 4000 cholecystectomies.Br J Surg 69:617 - 619 4. Fried LA, Lebrun GP, Norman RW, Fraser DB, Taylor MC, Roy PD, Marshall JC (1988) Extracorporeal shock-wave lithotripsy in the management of bile duct stones. AJR 151:923 -926 5. Glenn F (1975) Trends in surgical treatment of calculus disease of the biliary tract. Surg Gynecol Obstet 140: 877-884 6, Lux G, Ell CH, HochbergerJ, Mtiller D, Demling L (1986) The first successful endoscopic retrograde laser lithotripsy of common bile duct stones in man using a pulsed neodynium-YAGlaser. Endoscopy 18: 144-145 7. Neoptolemos JP, Hofmann AF, Moossa AR (1986) Chemical treatment of stones in the biliary tree. Br J Surg 73:515 -524 8. Riemann JF, Demling L (1983) Lithotripsy of bile duct stones. Endoscopy 15:191 - 196 9. Riemann JF, Seubert K, Demling L (1982) Clinical application of a new mechanical lithotriptor for smashing common bile duct stones. Endoscopy 14:226-230 10. Sauerbruch T, Holl J, Sackmann M (1987) Treatment of bile duct stones by extracorporeal shock waves. Semin Ultrasound CT MR 8: 155-161 11. SauerbruchT, Stem M, the Study Group for Shock-WaveLithotripsy of Bile Duct Stones (1989) Fragmentation of bile duct stones by extracorporeal shock-waves.A new approach to biliary calculi after failure of routine endoscopic measures. Gastroenterology96:146 152 12. Staritz M, Floth A, Rambow A, Wilbert D, Meyer zum Btischenfelde KH (1987) Behandlung groger Gallengangssteine dutch extrakorporale Stoi~wellenlithotripsie (ESL) mit einem Ger~t der zweiten Generation. Z Gastroentero125: 570- 576 13. Tanaka M, Yoshimoto H, Ikeda S, Matsumoto S, Xuan GR (1985) Two approachesfor electrohydraulic lithotripsy in the common bile duct. Surgery 98:313-318 14. Thistle JL, Carlson GL, Hofmann AF, LaRusso NF, MacCarty RL, Flynn GL, Higuchi WI, Babayan VK (1980) Monooctanoin, a dissolution agent for retained cholesterolbile duct stones: physicalproperties and clinical application. Gastroenterology78: 1016-1020 15. Vellacott KD, Powell PH (1979) Exploration of the common bile duct: a comparative study. Br J Surg 66:389-391
