Acute pancreatitis
DEFINITION AND CAUSES
Acute pancreatitis is an acute inflammatory injury of the pancreas caused by premature intrapancreatic activation of digestive enzymes. Common causes are gallstones and alcohol. Others include hypertriglyceridaemia, hypercalcaemia, drugs, ERCP, trauma, infection, autoimmune disease and genetic factors. If no cause is found after appropriate evaluation it is termed idiopathic.
PATHOPHYSIOLOGY AND CLASSIFICATION
Acinar cell injury and premature trypsinogen activation initiate enzyme-mediated autodigestion, inflammation and cytokine release. Local oedema, fat necrosis and haemorrhage may occur; systemic inflammation can cause capillary leak, shock, ARDS and renal injury. Revised Atlanta classification defines mild disease (no organ failure or complications), moderately severe (transient organ failure <48 hours and/or local/systemic complications) and severe (persistent organ failure >48 hours). Morphology is interstitial oedematous or necrotising pancreatitis.
CLINICAL FEATURES
Severe persistent epigastric pain often radiates to the back and may improve on leaning forward. Nausea, vomiting, abdominal tenderness, distension, fever and tachycardia are common. Severe cases may show hypotension, hypoxia, oliguria, confusion or shock. Cullen sign (periumbilical bruising) and Grey Turner sign (flank bruising) are rare late signs of haemorrhagic disease. Examine for gallstone disease, jaundice and signs of alcohol misuse.
DIAGNOSIS AND SEVERITY
Diagnosis requires two of three: characteristic pain; serum lipase (preferred) or amylase ≥3 times upper limit of normal; or characteristic imaging. Check FBC, urea/creatinine, electrolytes, glucose, calcium, liver tests, triglycerides and CRP. Ultrasound evaluates gallstones and bile duct dilatation. Contrast CT is not routinely needed at admission if diagnosis is clear; use it when diagnosis is uncertain or the patient fails to improve, usually after 48–72 hours to define necrosis/collections. Assess organ failure and monitor observations, urine output, oxygenation, BUN/creatinine and haematocrit. Scores such as BISAP or APACHE II can support risk assessment but do not replace clinical judgement.