Acute Pancreatitis

Diagnose first, then stage the physiology

The two-of-three rule prevents both reflex CT scanning and false reassurance from one laboratory value.

Acute pancreatitis requires at least two of three findings: characteristic upper abdominal pain, amylase or lipase at least 3 times the upper limit of normal, or characteristic imaging.

Lipase can remain elevated after symptoms evolve, can rise in renal failure and other abdominal illnesses, and can be falsely low with severe hypertriglyceridemia; it should not be serially trended as a severity marker.

Reserve contrast CT or MRI for diagnostic uncertainty, failure to improve after initial care, or concern for necrosis or another complication rather than ordering it reflexively at presentation.

The trigger changes what prevents recurrence

Gallstones and alcohol lead the list, but a disciplined cause search catches treatable alternatives.

Gallstones can transiently obstruct the shared ampullary outflow, while alcohol promotes acinar injury and recurrent attacks through several mechanisms.

When neither cause fits, measure triglycerides early and review calcium, medications, recent ERCP, trauma, infection, autoimmune disease, anatomic obstruction, and occult tumor when age or recurrence raises concern.

Hypertriglyceridemia is most convincing as the cause when triglycerides exceed 1,000 mg/dL and no stronger cause is present; lipemic interference can make pancreatic enzyme results deceptively low.

Do not label pancreatitis idiopathic until common, metabolic, medication, and structural causes have been considered.

A few thresholds change the branch

Use numbers as decision pivots, not as substitutes for the bedside course.

The diagnostic enzyme threshold is at least 3 times the upper limit of normal, while triglycerides above 1,000 mg/dL strongly support a hypertriglyceridemic cause when alternatives are absent.

Organ failure that resolves within 48 hours is transient; persistence beyond 48 hours defines severe disease.

Feed mild disease within 24 to 48 hours as tolerated, perform ERCP within 24 hours for cholangitis, and delay nonurgent intervention for stable necrosis until a mature wall develops, often about 4 weeks.

Thresholds open the door; physiology decides how fast to walk through it.

The retroperitoneal map explains the pain and procedures

The pancreas sits against the posterior abdominal wall and shares its distal outflow with the bile duct.

Posterior retroperitoneal inflammation makes epigastric pain bore through to the back and can track fluid along fascial planes into the lesser sac, paracolic gutters, and pelvis.

A stone at the ampulla can obstruct pancreatic and biliary outflow, but ERCP treats persistent biliary obstruction or cholangitis rather than the pancreatic inflammation itself.

Activated enzymes and inflammation injure peripancreatic fat, producing fat necrosis, calcium soap formation, and sometimes hypocalcemia; retroperitoneal hemorrhage may produce flank or periumbilical ecchymosis but these late signs are neither sensitive nor required.

Severity is organ failure, not enzyme drama

A very high lipase can accompany mild disease, while a falling lipase can coexist with shock.

Mild acute pancreatitis has no organ failure or local complication; moderately severe disease has transient organ failure, local complications, or worsening comorbidity.

Severe acute pancreatitis is defined by persistent organ failure lasting more than 48 hours, most importantly respiratory, cardiovascular, or renal failure.

Necrosis and collections matter, but persistent organ failure is the defining severity pivot and should drive monitored or intensive care.

Follow organs, not enzymes.

Support the patient and intervene only for a reason

Current care favors reassessed resuscitation, analgesia, early enteral nutrition, and cause-directed procedures.

Use isotonic crystalloid, commonly lactated Ringer solution, with moderate goal-directed resuscitation and frequent reassessment; correct hypovolemia without forcing fluid into patients developing overload, hypoxemia, heart failure, or renal dysfunction.

Provide adequate analgesia and antiemetics, and begin a low-fat solid oral diet within 24 to 48 hours as tolerated in mild disease; when oral intake is not feasible, use enteral tube feeding rather than parenteral nutrition.

Perform urgent ERCP for acute pancreatitis complicated by cholangitis and consider it for ongoing biliary obstruction; do not perform routine early ERCP for uncomplicated biliary pancreatitis without cholangitis.

Do not give prophylactic antibiotics for sterile pancreatitis or sterile necrosis. Treat cholangitis, pneumonia, bacteremia, urinary infection, or suspected or proven infected necrosis with an appropriate regimen.

For mild acute biliary pancreatitis, perform cholecystectomy during the index admission, preferably before discharge; substantial necrosis or collections may require individualized delay.