onsecutive
WfI thout
Commn-on
uct
Explorati'ons
Mortality
T. N. PAPPAS, M.D., T. B. SLIMANE, M.D., and D. C. BROOKS, M.D.
It has been suggested that the incidence of morbidity and mortality after common duct exploration no longer justifies its use in patients with a gallbladder in situ. Therefore endoscopic sphincterotomy has been advocated for removal of common duct stones before cholecystectomy in selected patients. The purpose of this study was to determine our current rate of retained common duct stones and the morbidity and mortality rates associated with common duct exploration. Charts of 100 consecutive patients who underwent cholecystectomy and common duct exploration from January 1982 through December 1986 were reviewed. Indications for duct exploration included jaundice, dilated common bile duct, gallstone pancreatitis, multiple small stones, and abnormal intraoperative cholangiogram. Common duct exploration was done by manual technique or choledochoscopy, as determined by the surgeon's preference. Only two patients required duodenotomy for extraction of difficult stones. There were no deaths in this series of consecutive common duct exploration. The total morbidity rate was 15.7%, which included a 5.3% incidence of retained common duct stones. There was a 7.4% major complication rate, including deep vein thrombosis, bleeding gastric ulcer, and pneumonia. The remaining complications were minor and did not prolong hospitalization. There was one wound infection and no postoperative pancreatitis. None of the complications were directly attributable to choledochotomy or duct exploration. All retained common duct stones were removed by endoscopic retrograde cholangiopancreatography or by angiographic basket and did not require reoperation. It is concluded that operative common duct exploration not requiring duodenotomy is safe and does not appreciably increase the incidence of complications after cholecystectomy. Endoscopic sphincterotomy continues to be the preferable alternative to operative common duct exploration for patients with retained common duct stones.
From the Duke University Medical Center, Durham, North Carolina, Charles Nicole's Hospital, Avril, Tunis, and Brigham and Women's Hospital, Boston, Massachusetts
there is debate as to whether patients with gallbladders in situ should have their common ducts cleared by endoscopic meanS.2'3 The endoscopic controversy is based on comparison of morbidity and mortality statistics for the operative versus the nonoperative approach. Endoscopic removal of common duct stones is successful in 80% to 90% of patients, with the mortality rate of less than 1%' Associated morbidity is also less than 15%. In contrast the published mortality rate for cholecystectomy and common duct exploration ranges from 3% to 5%, with the morbidity rate approaching 25% to 30% in some reports.4' Unfortunately the endoscopic data has been generated in the most recent decade, the 1 980s, while the operative morbidity and mortality rates are usually quoted from the 1 960s and 1 970s. The purpose of this study is to retrospectively review 100 consecutive common duct explorations to determine the incidence of retained stones and to determine the morbidity and mortality rate of this. procedure using the most current operative approaches and techniques. Materials and Methods
The
TRADITIONALLY STONES IN the common bile duct have been treated by common duct exploration. Recently it has become apparent that endoscopic removal of common duct stones is not only feasible but extremely safe. While it is clear that postoperative retained common duct stones are best removed nonoperatively,'I
duct
exploration
at the
Hospital during the period from January 1982 ber 1986 lected
(2)
were
retrospectively reviewed
(1) indication for
on
common
to Decem-
and data duct
was
col-
exploration,
procedure, (3) the operative find(4) the technique of common duct exploration,
urgency status of the
ings,
and
including
Address correspondence to T. N. Pappas, M.D., Duke University Medical Center, Department of Surgery, Box 3479, Durham, NC 277 10. Reprints will not be available. Accepted for publication August 3, 1989.
patients undergoing Brigham and Women's
charts of 100 consecutive
common
the
use
of the choledochoscope. All complica-
Mortality was defined as all deaths occurring within 30 days of operation or during the hospitalization if it exceeded 30 days. Morbidity was defined
tions
as
260
were
recorded.
any adverse outcome that occurred after
operation
but
VOl. 211 .,NO. 3
CONSECUTIVE COMMON DUCT EXPLORATIONS
before discharge. Adverse outcomes that occurred before operation and continued in the postoperative period were not characterized as morbidities. Complications were characterized as major or minor, depending on whether they prolonged hospitalization (major complications). Stones that were retained after common duct exploration were carefully noted and were included as complications. Care was taken to note whether the complications could be directly attributed to the duct exploration. Postoperative T-tube cholangiography was used as the primary evidence for retained common duct stones. Results One patient in this series of 100 consecutive patients was excluded because of cholangiographic and operative findings of sclerosing cholangitis. Four additional patients were excluded due to inadequate postoperative documentation in the patient's record with respect to complications, although there were no deaths in this group. Total postoperative morbidity was 15.7%. This included a 5.3% incidence of retained common duct stones. Thirty-five per cent of the cases were done on an urgent or emergent basis and 60% (9 of 15) of the complications occurred in this group. No complication occurred as a direct result of duct exploration. The details of the morbidities are noted in Table 1. There were no postoperative deaths among these consecutive unselected patients. Ninety-three of ninety-five patients had a T tube placed after common duct exploration. The remaining two had common duct exploration with a flexible choledochoscope through an enlarged cystic duct stump and, after having no stones found, it was the surgeon's preference to ligate the cystic duct without insertion of a T tube. Neither of these two patients experienced postoperative complications. Of the remaining 93 patients, all had postoperative T-tube cholangiograms 5 to 11 days after operation but before discharge or as an outpatient. Retained common duct stones were determined by the presence of filling defects that were clearly reproducible on multiple injecTABLE 1. Morbidity After Cholecystectomy and Common Duct Exploration
Number of Patients
Morbidity
Urinary tract infection
2
Ileus
I
Retained stone Wound infection Deep vein thrombosis Pneumonia Renal failure (resolved) Pulmonary edema Bleeding gastric ulcer Prolonged fever
5 I I I I
I I I
261
TABLE 2. Indication for Common Duct Exploration
Indication
Number of Patients
Jaundice Gallstone pancreatitis Enlarged common duct (intraoperative) Multiple small stones Abnormal cholangiogram Cholangitis
22 19 18 13 11 3
tions and multiple fluoroscopic conditions. All retained common duct stones were extracted nonoperatively. Endoscopic retrograde cholangiography (ERCP) was used in three patients and two patients had percutaneous basketing. Of the five cases of retained common duct stones, four were residual stones that were left with the knowledge of the surgeon, who suspected that the patient was at great risk for a duodenotomy. One retained stone was unexpected. Two patients in this series required duodenotomy or biliary bypass at the time of the original surgery. One of these patients suffered a prolonged ileus. The mean age of these 100 consecutive patients was 52.7 years, and the female to male ratio was 2.2 to 1. The indications for duct exploration are noted in Table 2. Thirteen per cent of the patients had stones retrieved on exploration of the common duct. Several other patients had stones that were manually pushed through the ampulla at exploration and were not retrieved. Operative procedures on these patients included cholecystectomy in 92 patients. The remaining patients had previous cholecystectomies. Common duct exploration was carried out by standard techniques. Longitudinal choledochotomy was made and manual exploration of the common duct was accomplished with a combination of red rubber irrigation catheters and stone forceps. Fortyeight of the ninety-three patients also underwent intraoperative choledochoscopy with flexible (37 patients) or rigid scope (12 patients), the type of scope determined by the operating surgeon. After common duct exploration, a T-tube cholangiogram was performed in 92% of the patients. Discussion This retrospective review demonstrates that common duct exploration can be performed with a very low morbidity rate and with no deaths. Importantly no complication was directly attributable to duct exploration. This data is in contrast to multiple previous studies that have demonstrated a relatively high incidence of postoperative deaths and complication after common duct exploration.' The improved nature of our postoperative statistics can be attributed to a wide variety of factors. As is noted in the Results section, several of these pa-
262
PAPPAS, SLIMANE, AND BROOKS
tients underwent urgent or emergent operation, which suggests that there was a relatively high-risk patient group. Most of the complications occurred in patients undergoing urgent or emergent operations. Our relatively low incidence of positive common duct exploration is consistent with previous findings that higher mortality rates are always encountered when common duct stones are found at exploration. Negative explorations are usually accompanied by very low incidences of morbidity and mortality.4'5 We also report a very low incidence of duodenotomy in this series (less than 2%). The requirement of duodenotomy or intestinal bypass to treat difficult-to-extract stones is associated with a dramatic increase in the number of deaths and complications.7 Duodenotomy to avoid a retained stone should be done only in low-risk patients. As with many relatively complex operations, trends over the past several years have suggested that morbidity and mortality rates have fallen, despite an aging population and patients at higher risk.89 In addition modem intraoperative cholangiographic and endoscopic techniques coupled with careful postoperative care have undoubtedly improved the morbidity and mortality rates. Advances in anesthetic management, critical care monitoring, and pharmacology have all produced safer and efficacious surgery. The lower morbidity and mortality rates with common duct exploration as documented in this study have an important bearing on decision making in reference to treatment of common duct stones. Gastroenterologists have suggested that ERCP should be used to extract common duct stones, either before cholecystectomy or in lieu of operation.2'6 This is based on the fact that ERCP is successful in approximately 80% to 90% in clearing the common duct and is associated with a relatively low incidence of recurrent common duct disease.' It has been suggested that before elective cholecystectomy, the common duct should be cleared by ERCP to produce a lower morbidity rate than the combination of cholecystectomy and common duct exploration does.6 Our data support the more traditional approach of cholecystectomy and common duct exploration, leaving ERCP to treat intentional or unintentional retained stones. If the decision to perform a duodenotomy is carefully made in low-risk patients, as it was in our series, acceptably low morbidity rates can be achieved while subjecting few patients to the small but real additional risks of ERCP. Patient selection should be the primary issue when the clinician is faced with choosing ERCP and sphincterotomy versus cholecystectomy and common duct exploration. Certainly patients in the elderly population with multiple comorbid conditions should reasonably be considered for
Ann. Surg. - March 1990
ERCP and sphincterotomy, thus avoiding the very high morbidity and mortality risks associated with biliary tract surgery in these patients.2 In contrast relatively young patients without comorbid conditions clearly benefit by removal of their gallbladder and operative clearance of their common bile duct. Short-term (3-year) follow-up of patients who have had sphincterotomy alone for the treatment of common duct stones demonstrates a 16% incidence of cholecystitis if stones are present in their gallbladders.3 When follow-up is extended beyond 3 years, the incidence of recurrent biliary tract disease will undoubtedly increase, and therefore young patients will likely benefit from early operation rather than ERCP. We present a series of consecutive common duct explorations with very low morbidity (15.7%) and mortality (0%) rates. Four of five retained stones were left intentionally, thus avoiding the added risk of duodenotomy. All five patients had their retained stones removed nonoperatively without complications. We recommended that operative cholecystectomy and common duct exploration continue to be the first line of therapy for stone disease of the gallbladder and bile duct. Duodenotomy for difficult-to-extract stones should be reserved for the low-risk patient, while an intentionally retained stone in a highrisk patient is best managed by postoperative ERCP. Patients with common bile duct stone symptoms and asymptomatic gallbladder stones may be safely treated with ERCP alone if they are elderly and represent a prohibitive operative risk. References 1. Lambert ME, Martin EF, Tweedle DEF. Endoscopic removal of retained stones after biliary surgery. Br J Surg 1988; 75:896-898. 2. Martin DF, Tweedle DEF. Endoscopic management of common duct stones without cholecystectomy. Br J Surg 1987; 74:209211. 3. Tanaka M, Ikeda S, Yoshimoto H, Matsumoto S. The long-term fate of the gallbladder after endoscopic sphincterotomy. Am J Surg 1987; 154:505-509. 4. Colcock BP, Perey B. Exploration of the common bile duct. Surg Gynecol Obstet 1964; 118:20-24. 5. Lrson RE, Hoogson JR, Priestley JT. The early and long-term results of 500 consecutive explorations of the common duct. Surg Gynecol Obstet 1966; 122:744-50. 6. Heinerman PM, Boeckl 0, Pimpl W. Selective ERCP and preoperative stone removal in bile duct surgery. Ann Surg 1989; 209: 267-271. 7. Baker AR, Neoptolemos JP, Leese T, Fossard DP. Choledochoduodenostomy, transduodenal sphincteroplasty and sphincterotomy for calculi of the common bile duct. Surg Gynecol Obstet 1987; 164:245-251. 8. Califf RM, Harrell FE, Lee KL, et al. Evolution of medical and surgical therapy for coronary artery disease: a 15-year perspective. JAMA 1989; 261:2077-2086. 9. Crist DW, Sitzman JF, Cameron JL. Improved hospital morbidity, mortality and survival after the Whipple procedure. Ann Surg 1987; 206:358-365.
WfI thout
Commn-on
uct
Explorati'ons
Mortality
T. N. PAPPAS, M.D., T. B. SLIMANE, M.D., and D. C. BROOKS, M.D.
It has been suggested that the incidence of morbidity and mortality after common duct exploration no longer justifies its use in patients with a gallbladder in situ. Therefore endoscopic sphincterotomy has been advocated for removal of common duct stones before cholecystectomy in selected patients. The purpose of this study was to determine our current rate of retained common duct stones and the morbidity and mortality rates associated with common duct exploration. Charts of 100 consecutive patients who underwent cholecystectomy and common duct exploration from January 1982 through December 1986 were reviewed. Indications for duct exploration included jaundice, dilated common bile duct, gallstone pancreatitis, multiple small stones, and abnormal intraoperative cholangiogram. Common duct exploration was done by manual technique or choledochoscopy, as determined by the surgeon's preference. Only two patients required duodenotomy for extraction of difficult stones. There were no deaths in this series of consecutive common duct exploration. The total morbidity rate was 15.7%, which included a 5.3% incidence of retained common duct stones. There was a 7.4% major complication rate, including deep vein thrombosis, bleeding gastric ulcer, and pneumonia. The remaining complications were minor and did not prolong hospitalization. There was one wound infection and no postoperative pancreatitis. None of the complications were directly attributable to choledochotomy or duct exploration. All retained common duct stones were removed by endoscopic retrograde cholangiopancreatography or by angiographic basket and did not require reoperation. It is concluded that operative common duct exploration not requiring duodenotomy is safe and does not appreciably increase the incidence of complications after cholecystectomy. Endoscopic sphincterotomy continues to be the preferable alternative to operative common duct exploration for patients with retained common duct stones.
From the Duke University Medical Center, Durham, North Carolina, Charles Nicole's Hospital, Avril, Tunis, and Brigham and Women's Hospital, Boston, Massachusetts
there is debate as to whether patients with gallbladders in situ should have their common ducts cleared by endoscopic meanS.2'3 The endoscopic controversy is based on comparison of morbidity and mortality statistics for the operative versus the nonoperative approach. Endoscopic removal of common duct stones is successful in 80% to 90% of patients, with the mortality rate of less than 1%' Associated morbidity is also less than 15%. In contrast the published mortality rate for cholecystectomy and common duct exploration ranges from 3% to 5%, with the morbidity rate approaching 25% to 30% in some reports.4' Unfortunately the endoscopic data has been generated in the most recent decade, the 1 980s, while the operative morbidity and mortality rates are usually quoted from the 1 960s and 1 970s. The purpose of this study is to retrospectively review 100 consecutive common duct explorations to determine the incidence of retained stones and to determine the morbidity and mortality rate of this. procedure using the most current operative approaches and techniques. Materials and Methods
The
TRADITIONALLY STONES IN the common bile duct have been treated by common duct exploration. Recently it has become apparent that endoscopic removal of common duct stones is not only feasible but extremely safe. While it is clear that postoperative retained common duct stones are best removed nonoperatively,'I
duct
exploration
at the
Hospital during the period from January 1982 ber 1986 lected
(2)
were
retrospectively reviewed
(1) indication for
on
common
to Decem-
and data duct
was
col-
exploration,
procedure, (3) the operative find(4) the technique of common duct exploration,
urgency status of the
ings,
and
including
Address correspondence to T. N. Pappas, M.D., Duke University Medical Center, Department of Surgery, Box 3479, Durham, NC 277 10. Reprints will not be available. Accepted for publication August 3, 1989.
patients undergoing Brigham and Women's
charts of 100 consecutive
common
the
use
of the choledochoscope. All complica-
Mortality was defined as all deaths occurring within 30 days of operation or during the hospitalization if it exceeded 30 days. Morbidity was defined
tions
as
260
were
recorded.
any adverse outcome that occurred after
operation
but
VOl. 211 .,NO. 3
CONSECUTIVE COMMON DUCT EXPLORATIONS
before discharge. Adverse outcomes that occurred before operation and continued in the postoperative period were not characterized as morbidities. Complications were characterized as major or minor, depending on whether they prolonged hospitalization (major complications). Stones that were retained after common duct exploration were carefully noted and were included as complications. Care was taken to note whether the complications could be directly attributed to the duct exploration. Postoperative T-tube cholangiography was used as the primary evidence for retained common duct stones. Results One patient in this series of 100 consecutive patients was excluded because of cholangiographic and operative findings of sclerosing cholangitis. Four additional patients were excluded due to inadequate postoperative documentation in the patient's record with respect to complications, although there were no deaths in this group. Total postoperative morbidity was 15.7%. This included a 5.3% incidence of retained common duct stones. Thirty-five per cent of the cases were done on an urgent or emergent basis and 60% (9 of 15) of the complications occurred in this group. No complication occurred as a direct result of duct exploration. The details of the morbidities are noted in Table 1. There were no postoperative deaths among these consecutive unselected patients. Ninety-three of ninety-five patients had a T tube placed after common duct exploration. The remaining two had common duct exploration with a flexible choledochoscope through an enlarged cystic duct stump and, after having no stones found, it was the surgeon's preference to ligate the cystic duct without insertion of a T tube. Neither of these two patients experienced postoperative complications. Of the remaining 93 patients, all had postoperative T-tube cholangiograms 5 to 11 days after operation but before discharge or as an outpatient. Retained common duct stones were determined by the presence of filling defects that were clearly reproducible on multiple injecTABLE 1. Morbidity After Cholecystectomy and Common Duct Exploration
Number of Patients
Morbidity
Urinary tract infection
2
Ileus
I
Retained stone Wound infection Deep vein thrombosis Pneumonia Renal failure (resolved) Pulmonary edema Bleeding gastric ulcer Prolonged fever
5 I I I I
I I I
261
TABLE 2. Indication for Common Duct Exploration
Indication
Number of Patients
Jaundice Gallstone pancreatitis Enlarged common duct (intraoperative) Multiple small stones Abnormal cholangiogram Cholangitis
22 19 18 13 11 3
tions and multiple fluoroscopic conditions. All retained common duct stones were extracted nonoperatively. Endoscopic retrograde cholangiography (ERCP) was used in three patients and two patients had percutaneous basketing. Of the five cases of retained common duct stones, four were residual stones that were left with the knowledge of the surgeon, who suspected that the patient was at great risk for a duodenotomy. One retained stone was unexpected. Two patients in this series required duodenotomy or biliary bypass at the time of the original surgery. One of these patients suffered a prolonged ileus. The mean age of these 100 consecutive patients was 52.7 years, and the female to male ratio was 2.2 to 1. The indications for duct exploration are noted in Table 2. Thirteen per cent of the patients had stones retrieved on exploration of the common duct. Several other patients had stones that were manually pushed through the ampulla at exploration and were not retrieved. Operative procedures on these patients included cholecystectomy in 92 patients. The remaining patients had previous cholecystectomies. Common duct exploration was carried out by standard techniques. Longitudinal choledochotomy was made and manual exploration of the common duct was accomplished with a combination of red rubber irrigation catheters and stone forceps. Fortyeight of the ninety-three patients also underwent intraoperative choledochoscopy with flexible (37 patients) or rigid scope (12 patients), the type of scope determined by the operating surgeon. After common duct exploration, a T-tube cholangiogram was performed in 92% of the patients. Discussion This retrospective review demonstrates that common duct exploration can be performed with a very low morbidity rate and with no deaths. Importantly no complication was directly attributable to duct exploration. This data is in contrast to multiple previous studies that have demonstrated a relatively high incidence of postoperative deaths and complication after common duct exploration.' The improved nature of our postoperative statistics can be attributed to a wide variety of factors. As is noted in the Results section, several of these pa-
262
PAPPAS, SLIMANE, AND BROOKS
tients underwent urgent or emergent operation, which suggests that there was a relatively high-risk patient group. Most of the complications occurred in patients undergoing urgent or emergent operations. Our relatively low incidence of positive common duct exploration is consistent with previous findings that higher mortality rates are always encountered when common duct stones are found at exploration. Negative explorations are usually accompanied by very low incidences of morbidity and mortality.4'5 We also report a very low incidence of duodenotomy in this series (less than 2%). The requirement of duodenotomy or intestinal bypass to treat difficult-to-extract stones is associated with a dramatic increase in the number of deaths and complications.7 Duodenotomy to avoid a retained stone should be done only in low-risk patients. As with many relatively complex operations, trends over the past several years have suggested that morbidity and mortality rates have fallen, despite an aging population and patients at higher risk.89 In addition modem intraoperative cholangiographic and endoscopic techniques coupled with careful postoperative care have undoubtedly improved the morbidity and mortality rates. Advances in anesthetic management, critical care monitoring, and pharmacology have all produced safer and efficacious surgery. The lower morbidity and mortality rates with common duct exploration as documented in this study have an important bearing on decision making in reference to treatment of common duct stones. Gastroenterologists have suggested that ERCP should be used to extract common duct stones, either before cholecystectomy or in lieu of operation.2'6 This is based on the fact that ERCP is successful in approximately 80% to 90% in clearing the common duct and is associated with a relatively low incidence of recurrent common duct disease.' It has been suggested that before elective cholecystectomy, the common duct should be cleared by ERCP to produce a lower morbidity rate than the combination of cholecystectomy and common duct exploration does.6 Our data support the more traditional approach of cholecystectomy and common duct exploration, leaving ERCP to treat intentional or unintentional retained stones. If the decision to perform a duodenotomy is carefully made in low-risk patients, as it was in our series, acceptably low morbidity rates can be achieved while subjecting few patients to the small but real additional risks of ERCP. Patient selection should be the primary issue when the clinician is faced with choosing ERCP and sphincterotomy versus cholecystectomy and common duct exploration. Certainly patients in the elderly population with multiple comorbid conditions should reasonably be considered for
Ann. Surg. - March 1990
ERCP and sphincterotomy, thus avoiding the very high morbidity and mortality risks associated with biliary tract surgery in these patients.2 In contrast relatively young patients without comorbid conditions clearly benefit by removal of their gallbladder and operative clearance of their common bile duct. Short-term (3-year) follow-up of patients who have had sphincterotomy alone for the treatment of common duct stones demonstrates a 16% incidence of cholecystitis if stones are present in their gallbladders.3 When follow-up is extended beyond 3 years, the incidence of recurrent biliary tract disease will undoubtedly increase, and therefore young patients will likely benefit from early operation rather than ERCP. We present a series of consecutive common duct explorations with very low morbidity (15.7%) and mortality (0%) rates. Four of five retained stones were left intentionally, thus avoiding the added risk of duodenotomy. All five patients had their retained stones removed nonoperatively without complications. We recommended that operative cholecystectomy and common duct exploration continue to be the first line of therapy for stone disease of the gallbladder and bile duct. Duodenotomy for difficult-to-extract stones should be reserved for the low-risk patient, while an intentionally retained stone in a highrisk patient is best managed by postoperative ERCP. Patients with common bile duct stone symptoms and asymptomatic gallbladder stones may be safely treated with ERCP alone if they are elderly and represent a prohibitive operative risk. References 1. Lambert ME, Martin EF, Tweedle DEF. Endoscopic removal of retained stones after biliary surgery. Br J Surg 1988; 75:896-898. 2. Martin DF, Tweedle DEF. Endoscopic management of common duct stones without cholecystectomy. Br J Surg 1987; 74:209211. 3. Tanaka M, Ikeda S, Yoshimoto H, Matsumoto S. The long-term fate of the gallbladder after endoscopic sphincterotomy. Am J Surg 1987; 154:505-509. 4. Colcock BP, Perey B. Exploration of the common bile duct. Surg Gynecol Obstet 1964; 118:20-24. 5. Lrson RE, Hoogson JR, Priestley JT. The early and long-term results of 500 consecutive explorations of the common duct. Surg Gynecol Obstet 1966; 122:744-50. 6. Heinerman PM, Boeckl 0, Pimpl W. Selective ERCP and preoperative stone removal in bile duct surgery. Ann Surg 1989; 209: 267-271. 7. Baker AR, Neoptolemos JP, Leese T, Fossard DP. Choledochoduodenostomy, transduodenal sphincteroplasty and sphincterotomy for calculi of the common bile duct. Surg Gynecol Obstet 1987; 164:245-251. 8. Califf RM, Harrell FE, Lee KL, et al. Evolution of medical and surgical therapy for coronary artery disease: a 15-year perspective. JAMA 1989; 261:2077-2086. 9. Crist DW, Sitzman JF, Cameron JL. Improved hospital morbidity, mortality and survival after the Whipple procedure. Ann Surg 1987; 206:358-365.
