AUTHOR AND EDITOR INFORMATION

Section 1 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

INTRODUCTION

Section 2 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

Background

Although there can be overlap in the characterization of infections in the pancreas, recognizing the different terms used in describing this complication of acute pancreatitis is important. A pancreatic abscess (PA) is a collection of pus resulting from tissue necrosis, liquefaction, and infection. Infected necrosis refers to bacterial contamination of necrotic pancreatic tissue in the absence of abscess formation. A pseudocyst is a peripancreatic fluid collection containing high concentrations of pancreatic enzymes within a defined fibrous wall and lacking an epithelial lining.

Pancreatic abscess is a late complication of acute necrotizing pancreatitis (ANP), occurring more than 4 weeks after the initial attack. The mortality rate associated with pancreatic abscess is generally less than that of infected necrosis. The mortality rate of pancreatitis may exceed 20% or more with infected pancreatic necrosis and is largely related to sepsis and multiorgan failure.

Pathophysiology

ANP is the most severe end of a spectrum of inflammation associated with pancreatitis. Inflammation causes cell death with resultant devitalized tissue, which is likely to become infected. The amount of necrotic tissue is the strongest predictor of mortality in ANP. After pancreatic necrosis occurs, 3 potential outcomes exist, resolution, pseudocyst, or abscess.  The role of proinflammatory cytokines in this process is being vigorously examined. 

Pancreatic abscesses form through various mechanisms, including fibrous wall formation around fluid collections, penetrating peptic ulcers, and secondary infection of pseudocysts. Pseudocysts arise as a complication of ANP. Over a period of 3-4 weeks, sequestration of necrotic tissue occurs, forming a fibrous capsule without an epithelial lining. At any point after the initial injury in ANP, infection of necrotic tissue may occur, leading to abscess formation. When this occurs prior to the formation of the fibrous wall, it is termed infected necrosis. Pseudocysts and abscesses can be single or multiple and vary greatly in size.

Of note, pseudocyst formation is directly related to the degree of necrosis present. Approximately 3% of patients with acute pancreatitis develop pancreatic abscess.

Balthazar and Ranson's radiographic staging criteria predict the formation of pseudocysts and, therefore, abscesses.

• Grade A – Normal pancreas
• Grade B - Focal or diffuse enlargement
• Grade C - Mild peripancreatic inflammatory changes
• Grade D - Single fluid collection
• Grade E - Two or more fluid collections or gas within the pancreas or within peripancreatic inflammation

In grade A, B, C, or D, the probability of abscess formation is less than 2%. With grade E disease (2 or more collections of peripancreatic fluid), the probability rises to 57%.

Frequency

United States

The incidence of pancreatitis is approximately 185,000 cases per year. At least 80% of cases are due to alcohol and cholelithiasis. ANP is reported by some to occur in approximately 20% of all episodes of pancreatitis. Although sterile necrosis may occur, a variable percentage develop infection of the necrotic tissue. Depending on the time course and the host's ability to encase the necrotic tissue, the lesion is either infected necrosis or an abscess.

Mortality/Morbidity

• Some studies have indicated a worse prognosis in idiopathic acute pancreatitis compared to pancreatitis induced by alcohol or biliary stones.
• Patients are at risk for sepsis and, ultimately, even death. The mortality rate approaches 100% if surgical intervention and drainage are not undertaken for infected necrosis or abscess.
• Pseudocysts may result in prolonged abdominal pain, rupture leading to acute peritonitis, fistula formation, and erosion into vessels with acute hemorrhage. Pancreatic ascites or pleural effusion may result.
• Pseudocysts or abscesses may also cause hollow viscus obstruction by compression of surrounding structures, including the colon, stomach, duodenum, and the common bile duct.

Sex

Differences in sexual predilection are based on the difference in frequency of causative factors of the pancreatitis.

• Women are more likely to have gallstone pancreatitis than men.
• Men have alcohol-induced pancreatitis more commonly than women.
• A difference in the rate of abscess formation between men and women has not been clearly demonstrated.

CLINICAL

Section 3 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

History

• Diagnosed pancreatitis with an unexpectedly prolonged course, hemodynamic instability, fever, failure of medical therapy, or the presence of fluid collections on CT scan all point to the possibility of necrosis and, potentially, abscess formation later in the course.
• Abscess formation takes weeks, and infected pancreatic necrosis may be diagnosed earlier in the course.

Physical

• Abdominal pain with or without a mass on palpation of the epigastrium is suggestive of parietal peritoneal irritation.
• Classic physical examination findings, such as Grey-Turner sign or Cullen sign, are supposedly characteristic of pancreatitis but rarely are noted in clinical practice.
• Other physical findings are nonspecific and include abnormal vital signs consistent with sepsis, abdominal guarding, and rebound tenderness.

Causes

• The inciting events for pancreatitis are legion; however, cholelithiasis and alcohol account for more than 80% of cases in the developed world.
• Peripancreatic fluid encased in a fibrinous capsule defines pseudocysts.
• Superinfection of pseudocysts is one way that pancreatic abscesses may form, though pseudocysts are not a prerequisite for abscess formation.
• Evidence suggests that colonic translocation of bacterial flora accounts for many cases of pancreatic infection.
• The most typical organisms isolated from infected necrosis and abscesses are enteric bacteria and Candida species.

DIFFERENTIALS

Section 4 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

WORKUP

Section 5 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

Lab Studies

• No specific hematologic studies define infected necrosis or pancreatic abscess.
• A persistently elevated white blood cell count with a left shift and positive blood cultures is suggestive of this diagnosis.
• The degree of pancreatic enzyme elevation does not directly indicate the degree of necrosis.

Imaging Studies

• The presence of air in necrotic tissue in a pseudocyst on imaging studies is specific for infection as well.
• Abdominal CT scan with IV contrast; ultrasound, either endoscopic or transabdominal; and MRI (with gadolinium) are potential modes for imaging pancreatic necrosis or abscess. MRI is becoming the imaging study of choice due to concerns regarding the use of iodinated contrast, which is said, by some, to devitalize marginal tissue, increasing the burden of necrotic tissue.
• The current criterion standard for initial evaluation is contrast-enhanced CT scan, which may reveal ischemic pancreatic tissue as evidenced by the lack of uptake of contrast. There is some suggestion that early CT scan may be detrimental in ANP, with IV contrast worsening ischemia.
• Consider repeat imaging in all patients with ANP who develop worsening abdominal pain, develop signs or symptoms of obstruction, or have a prolonged clinical course.
• MRI may be of some additional benefit in the acute evaluation of ANP; gadolinium does not cause a worsening of ischemia in experimental models.
• Pancreatic necrosis appears as devitalized tissue with decreased IV contrast present on CT scan or MRI. A pancreatic pseudocyst has a rim of fibrous tissue surrounding a pocket of peripancreatic fluid.  
• • Earlier accumulations of fluid without the fibrous tissue are referred to as peripancreatic fluid collections, and this formerly was referred to as phlegmon.
  • Demonstrable necrotic tissue in the pseudocyst may exist. Typically, this develops more than 3 weeks after the initial bout of pancreatitis.

Procedures

• CT-guided or ultrasound-guided needle aspiration  
• • The presence of either bacterial or fungal flora in pancreatic fluid collections usually aspirated via CT-guided needle biopsy is the sine qua non of pancreatic abscess. The presence of organisms on either Gram stain or culture is essential to establish a diagnosis of abscess.
  • Pancreatic fluid collections are frequent sequelae of pancreatitis, and endoscopic drainage of these collections is gaining acceptance as an alternative to surgical drainage. Endoscopic ultrasound (EUS)-guided drainage should be reserved for prepancreatic fluid collections located at the pancreatic tail. These fluid collections should be evaluated by EUS before attempts at endoscopic drainage.
• Surgical drainage  
• • Sterile necrosis may be followed with serial CT-guided drainage and continued antibiotics.
  • Surgical drainage of infected necrosis or an abscess is the procedure for cure. Placement of indwelling drains after the initial procedure may be necessary for complete resolution.

TREATMENT

Section 6 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

Medical Care

• Medical care generally is supportive, with attention paid to blood pressure and volume status.
• The role of appropriate prophylactic antibiotic therapy remains controversial but has gained support in clinical practice. 
• Guide the choice of antibiotics by the likely flora and degree of antibiotic penetration into the abscess and the other necrotic tissue.  
• • The most commonly isolated bacteria in pancreatic abscesses are enteric organisms, through translocation through the gut.
  • The most common pathogens are Escherichia coli, Klebsiella pneumoniae, Enterococcus faecalis, Staphylococcus aureus, Pseudomonas aeruginosa, Proteus mirabilis, and Streptococcus species.

Surgical Care

• Endoscopic sphincterotomy plays a role in patients with a dilated common bile duct from an impacted stone at risk of impending cholangitis. Surgery in acute pancreatitis is used for cholecystectomy in the patient with gallstone pancreatitis, as well as for infected pancreatic necrosis, pancreatic abscess, pseudocysts, and traumatic pancreatitis with a ruptured duct system. 
• Primary drainage of the abscess is the treatment of choice for pancreatic abscess.
• Cases have been reported of medical treatment of pancreatic abscess in which death has not resulted; however, the standard of care is drainage involving an open procedure.
• Case series have been reported of patients with an abscess who have been treated with CT-guided drainage tube placement, but these seem to show inferior results to open drainage. Recent advances in endoscopic treatment using EUS have made guided transgastric treatment of the complications of ANP possible. Pseudocyst drainage via the transgastric approach is now common. EUS-guided necrosectomy has been promising to date. In specialized centers, this is rapidly becoming the treatment of choice.  
• • CT-guided drainage has some role in patients who cannot tolerate an open procedure. EUS with transgastric drainage is another option.
  • Consideration can be given to medical management of nonsurgical candidates until their clinical status improves.

Consultations

• Gastroenterology
• General surgery
• Interventional radiology

Diet

• Nothing by mouth (NPO) or a jejunal feeding tube for total enteral nutrition (TEN) is initially recommended early for ANP. 
• • TEN may be used as prophylactic therapy for infected pancreatic necrosis, since it significantly decreases the incidence of pancreatic infectious complications and the frequency of multiple organ failure and mortality. 
  • No contraindication for enteral feeding exists if the pancreatitis has resolved.
• If the course is prolonged, the institution of total parenteral nutrition (TPN) can be of benefit.

Activity

Patients generally are hospitalized and unable to perform usual activities.

MEDICATION

Section 7 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

Antibiotics are the primary medical therapy in pancreatic abscess, used for the control of bacteremia and sepsis. Supportive care with fluids is needed, and the use of vasopressors may be required.

Drug Category: Antibiotics

Patients typically are bacteremic and/or septic.

FOLLOW-UP

Section 8 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

Further Outpatient Care

• See Patient Education.

Transfer

• Patients usually should be in an ICU setting because they may decompensate quickly and require aggressive treatment, including mechanical ventilation.

Complications

• Fistula formation
• • Enterocutaneous following surgery
  • Entero-entero
  • Enterovascular
• Recurrent pancreatitis
• Bowel obstruction
• Death

Patient Education

• Inform patients about the common causes of pancreatitis.
• Offer cholecystectomy to patients with gallstone pancreatitis if they are surgical candidates.
• Provide counseling for patients to abstain from alcohol use.
• Monitor patients for steatorrhea, and inform them about the potential for pancreatic insufficiency and the potential need for pancreatic enzyme and fat-soluble vitamin supplementation.
• For excellent patient education resources, visit eMedicine's Liver, Gallbladder, and Pancreas Center. Also, see eMedicine's patient education article Pancreatitis.

MISCELLANEOUS

Section 9 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

Medical/Legal Pitfalls

• Failure to image if pancreatitis is not improving
• Failure to sample fluid collection, if possible, for evidence of necrosis or abscess
• Failure to consider surgery for definitive treatment

ACKNOWLEDGMENTS

Section 10 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

The opinions and assertions contained herein are the private views of the authors and are not to be construed as official or as reflecting the views of the Department of the Army or the Department of Defense.

MULTIMEDIA

Section 11 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

Media file 1:  Contrast-enhanced CT scan of infected pancreatic pseudocyst.
	View Full Size Image
Media type:  CT

REFERENCES

Section 12 of 12

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

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Article Last Updated: Jun 12, 2008