Pancreatic fluid collections, necrotic debris collections, and abscesses are usually complications of acute necrotizing pancreatitis. According to the most recent classifications, complications of acute pancreatitis can be divided into acute, defined as a collection being present for less than 4 weeks or delayed defined by a collection being present for more than 4 weeks. In the acute phase, the fluid collection is not well defined and is labeled as a peripancreatic fluid collection. After four weeks, the fluid collection becomes much more organized with a definite fibrous wall, and it is then referred to as a pseudocyst. The pseudocyst is a cyst containing pancreatic enzymes, defined by a fibrous wall but lacks an epithelial lining. If this pseudocyst gets infected, it is referred to as a pancreatic abscess.
A pancreatic abscess is defined as a circumscribed intraabdominal collection of pus that is typically in the vicinity of the pancreas and contains little pancreatic necrosis. Infection is thought to occur via colonic translocation of bacteria. It usually develops in patients with pancreatic pseudocyst that become infected. Hence, its causative organisms are usually gram-negative flora bacteria, especially Escherichia coli, Klebsiella, and Pseudomonas, although gram-positive bacteria are also seen, most commonly Enterococcus. Patients that present with pancreatitis that do not improve after initial management and start developing systemic inflammatory response syndrome should increase the suspicion of some form of intraabdominal infection, especially of the pancreas.
Other causes might include penetrating peptic ulcers, gallstones, and excessive alcohol consumption because they increase the risk and the number of pancreatitis episodes. In rare cases, medications, blunt trauma, and the extension of abscesses from nearby structures can occur.
Acute pancreatitis is one of the most frequent gastrointestinal causes for hospital admission in the US. The annual incidence of acute pancreatitis ranges from 13 to 45/100,000 persons. A pancreatic abscess is a complication that occurs mostly in patients with acute pancreatitis, however, the exact epidemiology of this disease is not known.
Acute necrotizing pancreatitis usually presents as fluid collections in the pancreatic and peripancreatic regions, which may present as an acute necrotic collection (ANC) that does not have a definitive wall, or when they are more organized with well-defined wall-off necrosis (WON). These fluid collections initially are sterile but can become infected to develop a pancreatic abscess.
Histology review of patients diagnosed with pancreatic abscesses revealed that 65% were due to chronic pancreatitis, 22% from biliary tract disease, 5% were from duodenal diseases, and the remainder was from other causes.
History taking plays a major role in the diagnosis of pancreatic abscess. A pancreatic abscess usually occurs in patients with a history of pancreatitis or in patients prone to develop pancreatitis. Patients with pancreatitis usually present with abdominal pain, located in the epigastric region radiating to the back, that gets worse after consumption of a meal. They may present with nausea and vomiting as well. Keeping in mind the different causes of pancreatitis will guide the history.
Persistent fevers, worsening abdominal pain, and failure to improve despite appropriate initial management may all be suggestive of superimposed infection of the pancreas. Infection should be suspected in patients who do not improve after 7 to 10 days of hospitalization and supportive care, and in those who rapidly deteriorate. Although the development of systemic inflammatory response syndrome can be attributed to pancreatitis itself, a superimposed infection should be suspected.
Physical examination findings in patients with pancreatic infections generally mimic the symptoms of acute pancreatitis but are usually more severe and often occur after 7 to 10 days of hospitalization. Abdominal pain is located in the mid epigastric region. An associated mass may or may not be palpable. In severe pancreatitis, patients are often dehydrated on presentation. Hypotension and hypoxia may indicate progression to shock. Fevers can result from underlying infection but also occur in the setting of ongoing pancreatic inflammation.
Several laboratory tests can be sent if an infectious process in the pancreas is suspected. However, none are specific to the condition. A complete blood count (CBC) with differential, basic metabolic panel (BMP), liver function test (LFT), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), lactate dehydrogenase and blood cultures should be obtained in patients presenting with pancreatitis and not improving despite conservative management. CRP greater than 150 has been associated with the detection of the presence of pancreatic necrosis with a 100% sensitivity and 81.4% specificity. A hematocrit of higher than 44% has been established to be a risk factor for pancreatic necrosis and the development of an abscess.
Imaging studies are also required when the patient fails to improve within 72 hours of treatment.
Abdominal computed tomography (CT) scan with contrast and contrast-enhanced magnetic resonance imaging (MRI) are both options for assessment of pancreatic necrosis and abscesses, although CT is more commonly used. On imaging, the presence of extraluminal gas in the pancreatic and/or peripancreatic tissues is consistent with an underlying infection.
A suggested approach to pancreatic abscess:
The resolution of tachycardia, fevers, hypotension, as well as improvement in the patients' abdominal pain, are all markers of clinical improvement. However, they are not specific to the pancreatic abscess.
Daily CBC should be performed to ensure that the leukocytosis is resolving. For patients with diagnosed pancreatic abscess and bacteremia, serial blood cultures should be obtained to confirm the eventual clearance of the infection.
Differential diagnosis of a pancreatic abscess include:
The prognosis depends on the severity of the infection. It is a potentially severe complication that may result in the death of the patient if the appropriate management is not given. Patients are at risk of multiple organ failure and sepsis, and in cases in which the infected abscess is not removed either surgically or endoscopically, the mortality rate can reach 100%.
Acute pancreatitis is one of the most common gastrointestinal reasons for hospital admission. Patients should know that although pancreatitis is typically treated using conservative management with IV fluids, complications of pancreatitis can be devastating and might lead to death. It is important to educate patients about the importance of avoiding excessive alcohol intake, which is one of the most preventable causes of acute pancreatitis. Patients should also be encouraged to lead healthy lifestyles to include no smoking, eating a well-balanced diet, and exercising regularly to avoid the development of gallstones, which is one of the most common causes of pancreatitis.
Patients admitted to the hospital with acute pancreatitis that are not improving within 72 hours of conservative management should raise the suspicion for the presence of an abdominal abscess. CBC, blood cultures, as well as imaging should be obtained to rule out a deadly yet readily treatable condition.
A pancreatic abscess is a very serious condition, and the most effective way to approach the disease is with an interprofessional team that includes hospitalists, gastroenterologists, radiologists, general surgeons, intensivists, pharmacists, and nurses. The pharmacist can educate the patient on the medications that might cause pancreatitis and possibly find an alternative to them. The nurses might educate the patient on lowering the risk of acute pancreatitis, such as abstaining from alcohol, eating a low-fat diet, losing weight. Close follow-up with the gastroenterologist will help the patient stay dedicated to the treatment plan. [Level 5]
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