Approach to the Patient With Mild-to-Moderate Acute Pancreatitis?
Approach to the Patient With Mild-to-Moderate Acute Pancreatitis?
The patient is a 20-year-old white woman with mild-to-moderate acute pancreatitis; she has gallstones but no evidence of acute cholecystitis on ultrasound, computed tomography (CT), or magnetic resonance cholangiopancreatography (MRCP) scan. Liver function tests are mildly elevated. Other findings include a mildly dilated common bile duct (CBD); and choledochal cysts consistent with type IV, without definite CBD stones. On admission, her temperature was normal and white blood cell (WBC) count was 12.5 k (normal range 4000-10,000 cells/mm [4-10 k]), but her temperature increased to 101.6°F and the WBC count increased to 21.7 k. Piperacillin and tazobactam were started. Is endoscopic retrograde cholangiopancreatography (ERCP) indicated, and if so, is there a risk of chronic infection and cholangitis?
This young patient has a febrile illness with progressive elevation of peripheral WBC count. She has undergone multiple forms of cross-sectional abdominal imaging, including standard ultrasound, CT, and MRCP. These are reported to show a mildly dilated CBD (the upper limit of normal is 7 mm) and "choledochal cysts consistent with type IV." There are stones in the gallbladder, but none were visualized in the bile duct. The patient is said to have "mild-to-moderate pancreatitis." We are not told if this diagnosis is based on imaging and/or serologic data (ie, elevated serum amylase ± lipase). By report there are "mild liver function test elevations," but we do not have the specific values. The patient was started on 2 antibiotics, piperacillin and tazobactam, presumably on an empiric basis, as we are given no information to suggest positive blood cultures, etc. The following questions are posed: (a) Is ERCP indicated? and (b) If so, is there risk of chronic infection and cholangitis?
Not all classifications of acute pancreatitis recognize "moderate" severity. For example, the Ranson's score divides patients into predicted "mild" and "severe" outcome. The most important determinant of outcome in acute pancreatitis is the presence or absence of parenchymal necrosis, especially if it exceeds 30% of the gland. This is typically determined from contrast-enhanced helical CT scanning, which forms the basis of the Balthazar scoring system. If the patient's CT scan were to show significant necrosis, then the progressive fever and WBC elevation would be concerning for infected necrosis. However, this is typically a delayed phenomenon in acute pancreatitis, occurring weeks after the insult. Instrumentation of the pancreas, including percutaneous drainage of peripancreatic fluid collections and possibly ERCP, may cause sterile necrosis to become infected. We are not told the time course in this case, but I suspect that this patient is within a week of onset of her acute pancreatitis. In such a circumstance, her pyrexia and elevated WBC are more likely to be due to acute cholangitis, especially if liver function test abnormalities are present. The absence of choledocholithiasis on ultrasound, CT, and MRCP does not exclude the possibility of small (< 5 mm) stones or bile duct "sludge" (microlithiasis). Endoscopic ultrasound is proving to be a very sensitive tool for detecting both cholelithiasis and choledocholithiasis, and may be helpful in this patient, as a prelude to the more invasive ERCP.
The reported presence of "Type IV" choledochal cysts is the "wild card" here: the majority (80%) of choledochal cysts are Type I (by the Todani classification). Type IV choledochal cysts, which typically involve both intra- and extrahepatic bile ducts, are quite rare, especially in white individuals in the United States. Some forms of choledochal cyst are risk factors for acute pancreatitis, either due to biliary stasis and stone formation, or poorly understood factors related to anomalous pancreatico-biliary ductal drainage. In my experience, choledochal cysts are overdiagnosed on cross-sectional imaging studies: therefore, I would like to view the MRCP myself before accepting the diagnosis of "Type IV choledochal cyst." If this patient has acute cholangitis, the broad-spectrum antibiotics are appropriate, but may not prevent progression to liver abscess or systemic infection. Unimpeded flow of bile should be confirmed -- or established -- by ERCP or percutaneous transhepatic cholangiography, the former being preferred as it is much less invasive and uncomfortable for the patient. A biliary tree affected by 1 or more choledochal cysts can be the seat of chronic bacterial colonization, so instrumentation, even after a dose or two of broad-spectrum antibiotic(s), may result in rigors or other evidence of bacteremia.
I agree that ERCP after at least 2 or 3 doses of antibiotic is indicated in this patient. However, I would avoid opacifying the pancreatic duct; pancreatography is not indicated. If choledocholithiasis is confirmed, interval cholecystectomy would be indicated. In the setting of severe pancreatitis, with cholangitis excluded or treated, the question of infected necrosis would be addressed by percutaneous (CT-guided) aspiration of the necrotic tissue. A positive Gram stain in this setting used to be an indication for urgent surgery (necrosectomy), but the pendulum has swung away from rushing to surgery and toward broadening antibiotic coverage and percutaneously draining any accessible peripancreatic fluid collections. Fungal infection should also be considered in the management of fever and high WBC count in any severe acute pancreatitis patient whose retroperitoneum has been instrumented (eg, with percutaneous drain).
Patients with choledochal cysts may develop chronic biliary sepsis with or without instrumentation. Type III choledochal cysts (choledochoceles) are effectively managed by endoscopic sphincterotomy and can be left in place, given their low risk of malignant transformation. Other types of choledochal cyst carry a significant risk of cholangiocarcinoma developing over time, and should be surgically excised. Type V choledochal cysts (Caroli's disease) are often too extensive to manage by surgical drainage procedures and may be an indication for liver transplantation in selected individuals.
Question
The patient is a 20-year-old white woman with mild-to-moderate acute pancreatitis; she has gallstones but no evidence of acute cholecystitis on ultrasound, computed tomography (CT), or magnetic resonance cholangiopancreatography (MRCP) scan. Liver function tests are mildly elevated. Other findings include a mildly dilated common bile duct (CBD); and choledochal cysts consistent with type IV, without definite CBD stones. On admission, her temperature was normal and white blood cell (WBC) count was 12.5 k (normal range 4000-10,000 cells/mm [4-10 k]), but her temperature increased to 101.6°F and the WBC count increased to 21.7 k. Piperacillin and tazobactam were started. Is endoscopic retrograde cholangiopancreatography (ERCP) indicated, and if so, is there a risk of chronic infection and cholangitis?
Response from John Baillie, MB, ChB, FRCP, FACG
This young patient has a febrile illness with progressive elevation of peripheral WBC count. She has undergone multiple forms of cross-sectional abdominal imaging, including standard ultrasound, CT, and MRCP. These are reported to show a mildly dilated CBD (the upper limit of normal is 7 mm) and "choledochal cysts consistent with type IV." There are stones in the gallbladder, but none were visualized in the bile duct. The patient is said to have "mild-to-moderate pancreatitis." We are not told if this diagnosis is based on imaging and/or serologic data (ie, elevated serum amylase ± lipase). By report there are "mild liver function test elevations," but we do not have the specific values. The patient was started on 2 antibiotics, piperacillin and tazobactam, presumably on an empiric basis, as we are given no information to suggest positive blood cultures, etc. The following questions are posed: (a) Is ERCP indicated? and (b) If so, is there risk of chronic infection and cholangitis?
Not all classifications of acute pancreatitis recognize "moderate" severity. For example, the Ranson's score divides patients into predicted "mild" and "severe" outcome. The most important determinant of outcome in acute pancreatitis is the presence or absence of parenchymal necrosis, especially if it exceeds 30% of the gland. This is typically determined from contrast-enhanced helical CT scanning, which forms the basis of the Balthazar scoring system. If the patient's CT scan were to show significant necrosis, then the progressive fever and WBC elevation would be concerning for infected necrosis. However, this is typically a delayed phenomenon in acute pancreatitis, occurring weeks after the insult. Instrumentation of the pancreas, including percutaneous drainage of peripancreatic fluid collections and possibly ERCP, may cause sterile necrosis to become infected. We are not told the time course in this case, but I suspect that this patient is within a week of onset of her acute pancreatitis. In such a circumstance, her pyrexia and elevated WBC are more likely to be due to acute cholangitis, especially if liver function test abnormalities are present. The absence of choledocholithiasis on ultrasound, CT, and MRCP does not exclude the possibility of small (< 5 mm) stones or bile duct "sludge" (microlithiasis). Endoscopic ultrasound is proving to be a very sensitive tool for detecting both cholelithiasis and choledocholithiasis, and may be helpful in this patient, as a prelude to the more invasive ERCP.
The reported presence of "Type IV" choledochal cysts is the "wild card" here: the majority (80%) of choledochal cysts are Type I (by the Todani classification). Type IV choledochal cysts, which typically involve both intra- and extrahepatic bile ducts, are quite rare, especially in white individuals in the United States. Some forms of choledochal cyst are risk factors for acute pancreatitis, either due to biliary stasis and stone formation, or poorly understood factors related to anomalous pancreatico-biliary ductal drainage. In my experience, choledochal cysts are overdiagnosed on cross-sectional imaging studies: therefore, I would like to view the MRCP myself before accepting the diagnosis of "Type IV choledochal cyst." If this patient has acute cholangitis, the broad-spectrum antibiotics are appropriate, but may not prevent progression to liver abscess or systemic infection. Unimpeded flow of bile should be confirmed -- or established -- by ERCP or percutaneous transhepatic cholangiography, the former being preferred as it is much less invasive and uncomfortable for the patient. A biliary tree affected by 1 or more choledochal cysts can be the seat of chronic bacterial colonization, so instrumentation, even after a dose or two of broad-spectrum antibiotic(s), may result in rigors or other evidence of bacteremia.
I agree that ERCP after at least 2 or 3 doses of antibiotic is indicated in this patient. However, I would avoid opacifying the pancreatic duct; pancreatography is not indicated. If choledocholithiasis is confirmed, interval cholecystectomy would be indicated. In the setting of severe pancreatitis, with cholangitis excluded or treated, the question of infected necrosis would be addressed by percutaneous (CT-guided) aspiration of the necrotic tissue. A positive Gram stain in this setting used to be an indication for urgent surgery (necrosectomy), but the pendulum has swung away from rushing to surgery and toward broadening antibiotic coverage and percutaneously draining any accessible peripancreatic fluid collections. Fungal infection should also be considered in the management of fever and high WBC count in any severe acute pancreatitis patient whose retroperitoneum has been instrumented (eg, with percutaneous drain).
Patients with choledochal cysts may develop chronic biliary sepsis with or without instrumentation. Type III choledochal cysts (choledochoceles) are effectively managed by endoscopic sphincterotomy and can be left in place, given their low risk of malignant transformation. Other types of choledochal cyst carry a significant risk of cholangiocarcinoma developing over time, and should be surgically excised. Type V choledochal cysts (Caroli's disease) are often too extensive to manage by surgical drainage procedures and may be an indication for liver transplantation in selected individuals.
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