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General Approach
1 Resuscitation / R/O Critical Diagnosis
See Abdominal Pain — General for the initial clinical approach to the undifferentiated abdominal-pain patient.
Is the patient crashing / unstable? Begin simultaneous resuscitation and evaluation — ABCs, IV/O2/monitor, fluids or blood as indicated, and focused bedside assessment for the cause.
Peritoneal signs / concern for surgical abdomen? Consider perforation, ischemia, obstruction, hemorrhage, or other surgical pathology. If stable → focused US / CT based on suspicion. If unstable → urgent surgical evaluation; do not delay definitive care for imaging.
Once immediate threats are addressed, move from “Could this patient die from this?” → “Where is the pain coming from?”
2 Emergent Biliary Causes
Once the patient is stable and immediate catastrophes are excluded, narrow the upper abdominal source using the history, exam, labs, and focused imaging.
Biliary disease → think anatomically: where is the stone?
Ampulla / transient stone passage → gallstone pancreatitis
Historical red flags and labs help localize the process — episodic vs persistent pain, fever, jaundice, Murphy sign, ↑bilirubin / alkaline phosphatase, ↑lipase. RUQ US is usually the first imaging test, then HIDA, MRCP/EUS, or ERCP depending on the suspected disease.
3 Gastric / Pancreatic Causes
Acute pancreatitis → epigastric pain radiating to the back + N/V + ↑lipase; then determine etiology, especially gallstones vs alcohol.
Peptic ulcer disease → think NSAIDs / H. pylori and, more importantly, whether the ulcer is complicated by bleeding, perforation, or obstruction.
If dangerous disease and complicated PUD are excluded, dyspepsia / GERD become more likely outpatient diagnoses.
4 Other Causes / Mimics
Do not anchor on the location of tenderness. Always look above and below the area being evaluated.
Above the abdomen: ACS may present with epigastric discomfort; lower-lobe pneumonia and PE may present as upper abdominal / lower chest pain.
Hepatic / splenic: hepatitis, liver abscess, splenic infarct / injury / rupture may mimic more common upper-GI disease.
Below the abdomen: early appendicitis may begin with epigastric / periumbilical pain before migrating to the RLQ.
If the GI workup does not fit the clinical picture, re-open the differential rather than defaulting to “gastritis.”
01Resuscitation / R/O Critical Diagnosis
See Abdominal Pain — General for the initial approach to the undifferentiated abdominal-pain patient.
Is the patient crashing / unstable? Begin resuscitation and diagnostic evaluation simultaneously — ABCs, IV/O2/monitor, fluids or blood as indicated, and rapid bedside assessment for the cause.
R/O immediately life-threatening causes — perforation, mesenteric ischemia, hemorrhage/AAA, bowel obstruction, ectopic pregnancy when applicable, or other surgical catastrophe.
Peritoneal signs / concern for surgical abdomen?
Stable → focused US / CT based on the suspected diagnosis.
Unstable → urgent surgical evaluation; do not delay definitive care for imaging.
Reassess after initial stabilization. Once the immediate threats are addressed, shift from “Could this patient die from this?” → “Where is the pain coming from?”
Then use the location, pain pattern, exam, and focused labs/imaging to narrow toward biliary, pancreatic, gastric, or other causes.
02Emergent Biliary Causes
Biliary Tract Disease
Cholelithiasis
Gallstones are common and usually asymptomatic.
Most gallstones are incidental and never cause symptoms. Merck
Finding gallstones does not automatically mean they are causing the patient's abdominal pain.
The clinical pain pattern must fit biliary disease before attributing symptoms to cholelithiasis.
The degree of lipase elevation does not determine disease severity.
Do not routinely CT a straightforward case.
CT → diagnosis unclear or failure to improve clinically within 48–72 hours ACG 2024
RUQ ultrasound to evaluate for gallstone / biliary etiology.
Severity — Revised Atlanta Classification
Local complications include peripancreatic fluid collections, pancreatic/peripancreatic necrosis, pseudocyst, and walled-off necrosis. Revised Atlanta Classification
Organ failure / persistent SIRS → monitored or ICU-level setting as appropriate ACG 2024
Special Etiology — Hypertriglyceridemia
If gallstones and significant alcohol use are absent, check serum triglycerides.
TG >1,000 mg/dL strongly supports hypertriglyceridemia as the cause. ACG 2024
Treat the pancreatitis supportively and correct the metabolic cause.
Uncontrolled diabetes / significant hyperglycemia → insulin infusion is appropriate and will also lower triglycerides.
In patients without diabetes, routine insulin infusion is not established as standard therapy. Endocrine Society
Plasmapheresis is not routine first-line therapy; consider only selected extraordinary or refractory cases. Endocrine Society
After the acute episode, address secondary causes and institute long-term triglyceride-lowering therapy, commonly including a fibrate when appropriate.
Treatment / Disposition
Analgesia
Moderate, reassessment-driven IV fluids; LR preferred ACG 2024
Avoid indiscriminate large-volume resuscitation.
The WATERFALL trial found substantially more fluid overload with aggressive hydration without improved clinical outcomes. WATERFALL
Early oral feeding as tolerated rather than routine prolonged NPO / bowel rest. ACG 2024
No prophylactic antibiotics for sterile pancreatic necrosis. ACG 2024
Necrosis alone does not mandate early surgery.
If intervention is required and the patient is stable, favor delayed, minimally invasive / step-up management rather than early open surgery. ACG 2024
