Sandbox:pancreatic abscess

# Overview
Pancreatic abscess is an unusual and rare, but life threatening complication of acute pancreatitis. It develop 5 weeks after the onset of pancreatitis and after onset of symptoms and subsidence of the acute phase of pancreatitis. Most of the pancreatic abscesses are developed from the progressive liquefaction of necrotic pancreatic and peri-pancreatic tissues, but some arise from infection of peripancreatic fluid or collections elsewhere in the peritoneal cavity. It is the most dangerous complication and the most common cause of death for acute pancreatitis.

# Definition
Pancreatic abscess is defined as a localized collection of pus surrounded by a more or less distinct capsula in inflamed pancreas.

# Historical Perspective

# Pathophysiology

# Causes

## Common Causes
Common organisms causing pancreatic abscess are as follows:
Aerobic bacteria
- Enterococcus
- Escherichia coli
- Klebsiella pneumoniae
- Pseudomonas aeruginosa
- Staphylococcus aureus
- Proteus
Anaerobic bacteria
- Bacteriodes fragilis
- Clostridium perfringens

# Differentiating Pancreatic Abscess from other Diseases
Pancreatic abscess should be diagnosed early and treat promptly not only to reduce morbidity and mortality, but also it is important to differentiate from other pancreatic disesases such recurrent pancreatitis, pancreatic psuedocysts etc. as the undrained abscess carreies high risk of mortality.
- Recurrent pancreatitis
Pancreatic necrosis
CT findings: Well marginated zones of non-enhanced pancreatic parenchyma
Pancreatic abscess
CT findings: Absent or limited necrosis
Infected pseudocyst

# Epidemiology and Demographics

## Prevalence

## Incidence
Incidence of pancreatic abscess is unknown, but McClave et al reported it as 2-5% among patients hospitalized for pancreatitis.

## Case Fatality Rate
Mortality rate of pancreatic abscess is varies depending upon the severity of pancreatitis with range of 10-59%.

## Age

## Gender

## Race

## Developed Countries

## Developing Countries

# Risk Factors
- History of alcoholic pancreatitis who fails to respond to medical therapy

# Natural History, Complications and Prognosis

## Complications

## Prognosis
Prognosis of pancreatic abscess depends on the time of diagnosis and treatment. Outcome of pancreatic abscess is generally based on the severity of the infection. It is however a severe complication which may result in the death of the patient if the appropriate treatment is not administered. Patients are at risk of sepsis and multiple organ failure and in patients with delay in surgery to remove infected abscess, the mortality rate can get to 100%.\
Poor prognostic factors
- Delayed diagnosis

# Association
- Biliary tract disease
- Alcohol addiction
- Carcinoma
- Peptic ulcer
- Trauma
- Polyarteritis nodosa

# Diagnosis
As the clinical presentation of pancreatic abscess is variable or even obscure, it should be considered in any febrile patient even 2 weeks after an attack of acute pancreatitis, even in the absence of other symptoms.

## History and Symptoms

### Common Symptoms
Presenting symptoms of pancreatic abscess are vague and variable, but common symptoms include:
- Abdominal pain
- Back pain
- Nausea and vomiting
- Weight loss

### Less common symptoms
- Melena
- Diarrhoea

## Vital signs
- High grade fever (greater than 37.8C)
- Upper abdominal pain
- Failure to thrive

## Physical Examination Findings
- Abdominal tenderness
- Palpable abdominal mass
- Abdominal distention

## Lab Findings

### Blood Tests
- CBC with differential: Leukocytosis (range between 10,500 to 35,00O/mm3)
- Blood culture: Low sensitivity to diagnose causative organism in pancreatic abscess as shows positivity in few cases, but it helps to distinguish abscesses from sterile pseudocysts and provide guidance for selection of antibiotics.

## Imaging
Imaging studies are crucial in the diagnosis and treatment of pancreatic abscess.
Both ultrasonography and computed tomography (CT) can be helpful with the diagnosis and localization of pancreatic abscesses, which may extend from the pancreas anywhere (e.g. retroperitoneum, mesentery, mediastinum, and even the neck or genitalia).

### X-ray
- Shows extraluminal (pancreas or lesser sac) gas bubbles suggesting abscess
- Disclosed pleural effusion
- Diaphragmatic elevation
- Basilar atelectasis

### Ultrasound
- Shows fluid filled sac suggesting abscess

### CT
CT had a sensitivity of 74%, compared with 35% for ultrasound in the diagnosis of pancreatic abscess.

## Fine Needle Aspiration
Advantages
- Fine needle aspiration can distinguish sterile inflammation from infection and it is the procedure of choice in the verification of bacterial infection.
- High sensitivity of 90% to 100%
- Low complication rate
- It aid in the early diagnosis of infectious complications of pancreatic abscess and to avoid unnecessary laparotomy.

# Treatment

## Surgical Therapy
Surgical therapy is the traditional method of treatment of pancreatic abscesses, usually by inserting one or more non-traumatic drains through transperitoneal or throguh flank or retroperitoneum into the abscess cavity. Failure of the surgical drainage might be due to the reluctance to expose the cavity widely and to debride the necrotic components aggressively.

## Transpapillary Drainage

## Endoscopic Drainage
Indications
- Patients who are unfit for surgical drainage.
Advantages
- Less invasive
- Potentially safe