Acute Pancreatitis

Acute pancreatitis (AP), also referred to as acute pancreatic necrosis, is a sudden inflammation of the pancreas. The primary causes of AP include gallstone obstruction, heavy alcohol use, systemic diseases, trauma, and mumps in children. AP can be a single event, recur, or progress to chronic pancreatitis and pancreatic failure. Treatment varies depending on the severity, ranging from conservative measures to intensive care unit (ICU) admission for severe cases.

Signs and Symptoms

Common symptoms of acute pancreatitis include severe epigastric pain that radiates to the back, nausea, vomiting, loss of appetite, fever, chills, hemodynamic instability, tachycardia, respiratory distress, peritonitis, and hiccups. Severe disease may present with uncommon symptoms such as Grey-Turner's sign, Cullen's sign, pleural effusions, Grünwald sign, Körte's sign, Kamenchik's sign, Mayo-Robson's sign, and Mayo-Robson's point.

Complications

Complications of acute pancreatitis can be locoregional or systemic. Locoregional complications include pancreatic pseudocyst, phlegmon/abscess formation, splenic artery pseudoaneurysms, haemorrhage, thrombosis, duodenal obstruction, common bile duct obstruction, and pancreatic ascites. Systemic complications include acute respiratory distress syndrome (ARDS), multiple organ dysfunction syndrome, disseminated intravascular coagulation (DIC), hypocalcaemia, hyperglycaemia, insulin-dependent diabetes mellitus, malabsorption, and a variety of metabolic, respiratory, renal, circulatory, gastrointestinal, hepatobiliary, neurologic, hematologic, and dermatologic complications.

Causes

The most common causes of acute pancreatitis are biliary pancreatitis due to gallstones, alcohol, idiopathic origins, metabolic disorders, post-endoscopic retrograde cholangiopancreatography (ERCP), abdominal trauma, penetrating ulcers, pancreatic carcinoma, various drugs, infections, structural abnormalities, radiotherapy, autoimmune pancreatitis, and severe hypertriglyceridaemia. Less common causes include scorpion venom, Chinese liver fluke, ischaemia from surgeries, fat necrosis, pregnancy, infections other than mumps, hyperparathyroidism, valproic acid, cystic fibrosis, anorexia or bulimia, and codeine phosphate reaction.

Diagnosis

Diagnosis of acute pancreatitis involves clinical history, physical examination, blood investigations, and imaging techniques. The presence of at least two out of three criteria—abdominal pain, elevated serum lipase or amylase, and consistent abdominal imaging findings—confirms the diagnosis.

Differential Diagnosis

Differential diagnoses include perforated peptic ulcer, biliary colic, acute cholecystitis, pneumonia, pleuritic pain, and myocardial infarction.

Biochemical

Elevated serum amylase and lipase levels are indicative of acute pancreatitis, but these tests do not assess disease severity. Serum lipase is preferred for diagnosis due to its higher sensitivity and specificity.

Imaging

A combination of triple-phase abdominal CT and abdominal ultrasound is considered the gold standard for evaluating acute pancreatitis. MRI and MRCP can also provide detailed imaging, especially useful for patients allergic to CT contrast materials.

Treatment

Initial management includes aggressive fluid resuscitation, pain control, nothing by mouth, and nutritional support.

Fluid Replacement

Aggressive hydration with isotonic crystalloid solutions is very important. Fluid requirements should be reassessed frequently in the first 24 to 48 hours.

Pain Control

Pain is managed with intravenous opioids like hydromorphone or fentanyl. Meperidine is less favoured due to its short half-life and risk of neuromuscular side effects.

Bowel Rest

Patients are kept nil by mouth to allow the pancreas to rest. Post-pyloric enteral feeding is preferred over total parenteral nutrition to reduce the risk of relapse.

Nutritional Support

Early, post-pyloric enteral feeding is now preferred due to its physiological benefits and reduced side effects compared to TPN.

Oxygen and Antibiotics

Oxygen may be provided if Pao2 levels fall below 70mm Hg. Antibiotics are started if an infection is suspected but should be discontinued if cultures are negative.

Endoscopic Retrograde Cholangiopancreatography (ERCP)

ERCP is indicated if a gallstone is detected or if there is clinical deterioration or lack of improvement after 24 hours.

Surgery

Surgery is reserved for infected pancreatic necrosis, diagnostic uncertainty, and complications. Infection is diagnosed by gas bubbles on CT scan or positive bacterial culture from FNA.

Prognostic Scoring Systems

Prognostic scoring systems such as the Ranson Criteria, APACHE II, Balthazar score, Glasgow score, and BISAP score help predict the severity and outcomes of acute pancreatitis. These scores guide the need for intensive care and help predict mortality rates.

Ranson Score

The Ranson score uses criteria at admission and within 48 hours to predict the severity of acute pancreatitis.

APACHE II Score

APACHE II is used to predict mortality and assess severity at admission and during the first few days of hospitalisation.

Balthazar Score

The Computed Tomography Severity Index (CTSI) assesses the severity of acute pancreatitis based on CT imaging findings.

Glasgow and BISAP Scores

The Glasgow score is valid for both gallstone and alcohol-induced pancreatitis, while the BISAP score predicts mortality risk using fewer variables.

Epidemiology

In the United States, acute pancreatitis has an annual incidence of 18 cases per 100,000 population, accounting for 220,000 hospitalizations. The incidence has increased over time, but mortality rates have remained stable due to better outcomes. The most common cause in Western countries is alcohol, while in Eastern countries, gallstones are the leading cause.

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Self-assessment MCQs (single best answer)

What is the most common cause of acute pancreatitis in Western countries?

Which of the following is NOT a common symptom of acute pancreatitis?

Which imaging modality is considered the gold standard for evaluating acute pancreatitis?

Which biochemical marker is preferred for the diagnosis of acute pancreatitis due to its higher sensitivity and specificity?

Which prognostic scoring system uses criteria at admission and within 48 hours to predict the severity of acute pancreatitis?

Which of the following is a locoregional complication of acute pancreatitis?

What is the first-line management for pain control in acute pancreatitis?

Which of the following is NOT a cause of acute pancreatitis?

In the treatment of acute pancreatitis, why is post-pyloric enteral feeding preferred over total parenteral nutrition?

Which sign is characterised by ecchymosis of the flanks and is associated with severe acute pancreatitis?