A Gallstone Begins Its Descent
One small stone starts a cascade toward acute pancreatitis.
- ~25M: Gallstone carriers, US (most stay silent for life)
- ~40%: Gallstone pancreatitis share (of all acute pancreatitis cases)
- <5 mm: Stone size at highest risk (small stones migrate easiest)
- 1–5 mm: Cystic duct diameter (narrow passage stones must clear)
Why stones start moving
Gallbladder contraction after a fatty meal pushes stones out.
The route downstream
Cystic duct joins the common bile duct toward the duodenum.
Smaller stones travel farther and jam more easily than large ones.
The danger point ahead
The ampulla of Vater is the shared, narrowest chokepoint.
Impaction at the Ampulla of Vater
One stone wedges where two critical ducts merge.
- 1: Shared channel (ampulla drains bile and pancreas)
- 1: Sphincter of Oddi (muscular valve stones can jam)
- Hours: Onset after impaction (symptoms follow the blockage fast)
- To back: Epigastric pain radiation (classic presenting complaint)
A shared anatomical funnel
Bile duct and pancreatic duct fuse just before the duodenum.
Two systems, one jam
A single stone can block bile flow and pancreatic drainage together.
Dual obstruction is what makes ampullary stones so dangerous.
Immediate consequences
Bile backs into the liver; pancreatic enzymes back into the gland.
Pancreatic Secretions Cannot Drain
Trapped enzymes raise pressure inside the pancreatic duct.
- ~15 mmHg: Normal duct pressure (baseline pancreatic secretion pressure)
- >40 mmHg: Obstructed duct pressure (can rise well beyond normal)
- Early: Acinar cell injury (begins within hours of blockage)
- Premature: Trypsinogen activation (enzymes activate inside the gland)
Pressure builds behind the stone
Continued secretion into a blocked duct raises intraductal pressure.
Enzymes activate too early
Trypsinogen converts to trypsin inside the pancreas itself.
Self-digestion begins before enzymes ever leave the gland.
Local tissue damage spreads
Acinar cell injury triggers inflammation and further enzyme leakage.
Amylase and Lipase Surge into Blood
Damaged acinar cells spill enzymes straight into circulation.
- 2–12 h: Amylase rise (after obstruction begins)
- 4–8 h: Lipase rise (stays elevated longer than amylase)
- >3× ULN: Diagnostic threshold (lipase or amylase above normal)
- Higher: Lipase specificity (more specific to pancreas than amylase)
Why levels spike so fast
Injured acinar membranes leak enzymes directly into capillaries.
Amylase versus lipase kinetics
Lipase rises later but persists days longer than amylase.
Lipase alone is now the preferred single diagnostic test.
Confirming the diagnosis
Levels above three times normal confirm acute pancreatitis.
Ranson Criteria Predict Outcome
Eleven clinical measures combine into one severity score.
- 5: Admission criteria (age, WBC, glucose, LDH, AST)
- 6: 48-hour criteria (measured a day after admission)
- ~2%: Mortality, 0–2 met (mild disease course)
- ~40%+: Mortality, ≥6 met (severe, high-risk course)
Two scoring windows
Five criteria at admission, six more measured at 48 hours.
Turning counts into risk
Each criterion met adds one point toward total severity.
Three or more points signals a substantially worse prognosis.
Guiding the next decision
Higher scores push toward ICU-level monitoring and imaging.