Use structured clinical reasoning process — combining pattern recognition, systematic questioning, physical examination, and targeted testing.
Before even asking a question, observe:
Is this the patient unstable or stable?
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| Letter | Question | What it reveals |
|---|---|---|
| S — Site | Where exactly is the pain? | Organ localization |
| O — Onset | When did it start? Sudden or gradual? | Vascular vs. inflammatory vs. functional |
| C — Character | Burning, cramping, stabbing, dull? | Type of tissue involved |
| R — Radiation | Does it go anywhere else? | Classic patterns (e.g., shoulder = diaphragm irritation) |
| A — Associations | Nausea? Fever? Bowel changes? Urinary symptoms? | Systemic vs. localized |
| T — Timing | Constant or comes and goes? Getting better or worse? | Acute vs. chronic, progressive vs. resolving |
| E — Exacerbating/Relieving | What makes it worse or better? | Functional clues (food, position, movement, defecation) |
| S — Severity | Score 1–10 | Urgency and clinical weight |
The physician uses a systematic, layered exam:
Looking at the abdomen for distension, visible peristalsis, bruising (Cullen's/Grey Turner's sign in pancreatitis), surgical scars, hernias.
Starting away from the pain, moving toward it:
| Finding | Implication |
|---|---|
| Voluntary guarding | Patient tenses muscles consciously — pain present |
| Involuntary guarding | Reflex muscle rigidity — peritoneal irritation |
| Rebound tenderness | Pain worse when pressure released — peritonitis |
| Murphy's sign (+) | Pain on inspiration during RUQ palpation — cholecystitis |
| McBurney's point tenderness | RLQ point tenderness — appendicitis |
| Rovsing's sign (+) | LLQ pressure causes RLQ pain — appendicitis |
| Psoas sign (+) | Pain on hip extension — retrocecal appendicitis |
| Obturator sign (+) | Pain on internal hip rotation — pelvic inflammation or appendicitis |
| Carnett's sign | Pain increases with tensed abdominal muscles — abdominal wall origin, not visceral |
| Organomegaly | Enlarged liver/spleen — hepatic or hematologic cause |
After history and exam, the physician mentally ranks diagnoses into three categories:
| Category | Meaning |
|---|---|
| Must not miss | Life-threatening if delayed — ectopic pregnancy, aortic aneurysm, mesenteric ischemia, appendicitis |
| Most likely | Fits the clinical picture best — the working diagnosis |
| Worth considering | Less likely but consistent with findings |
Sudden severe epigastric pain + rigid abdomen → Rule out: Perforated ulcer Tearing pain radiating to back + pulsatile mass → Rule out: Ruptured aortic aneurysm (AAA) RLQ pain + fever + elevated WBC + migrating pain → Rule out: Appendicitis Reproductive age female + amenorrhea + LLQ/RLQ pain → Rule out: Ectopic pregnancy (until proven otherwise) Elderly + diffuse pain + disproportionate to exam findings → Rule out: Mesenteric ischemia Sudden severe pain + peritoneal signs → Rule out: Perforation / Peritonitis
Rather than ordering every test, a physician orders tests that will change management based on the leading differential:
| Test | Reason |
|---|---|
| CBC | WBC elevation → infection/inflammation; anemia → bleeding |
| CRP / ESR | General inflammation markers |
| LFTs (AST, ALT, ALP, bilirubin) | Liver/biliary disease |
| Lipase / Amylase | Pancreatitis |
| Creatinine / BMP | Kidney function, electrolytes |
| Beta-hCG | Rule out pregnancy in all women of reproductive age — always |
| Lactate | Ischemia or sepsis |
| Coagulation studies | If bleeding suspected |
| Modality | Best For |
|---|---|
| Ultrasound | Gallstones, ovarian cysts, appendix (in children/thin patients), free fluid, aorta |
| CT Abdomen/Pelvis (with contrast) | Gold standard for most acute abdominal pain — appendicitis, diverticulitis, obstruction, masses |
| Plain X-ray (AXR) | Obstruction (air-fluid levels), free air under diaphragm (perforation) |
| MRI | Preferred in pregnancy; liver, biliary, pelvic detail |
| Endoscopy (upper/lower) | Ulcers, IBD, bleeding, cancer — not acute but definitive |
Physicians use validated scores to objectify their reasoning:
| Score | Used For | Components |
|---|---|---|
| Alvarado Score | Appendicitis probability | Pain migration, anorexia, nausea, RLQ tenderness, rebound, fever, WBC elevation |
| Ranson's Criteria | Pancreatitis severity | Age, WBC, glucose, LDH, AST on admission + at 48h |
| CURB-65 (modified) | Infection severity | Confusion, urea, RR, BP, age |
| Rome IV Criteria | IBS / functional GI diagnosis | Symptom pattern, duration, absence of organic cause |
| Child-Pugh / MELD | Liver disease severity | Used if hepatic cause identified |
The physician integrates everything into one of four pathways:
All data integrated │ ├─► SURGICAL EMERGENCY │ → Immediate surgical consult │ → Examples: Appendicitis, perforation, AAA, ectopic pregnancy, obstruction │ ├─► MEDICAL ADMISSION │ → IV fluids, medication, monitoring, further workup inpatient │ → Examples: Pancreatitis, severe infection, IBD flare, pyelonephritis │ ├─► OUTPATIENT MANAGEMENT + FOLLOW-UP │ → Prescription, lifestyle guidance, scheduled investigations │ → Examples: GERD, mild gastritis, IBS, UTI, diverticulitis (uncomplicated) │ └─► WATCHFUL WAITING / OBSERVATION → "Watch and wait" with clear return precautions → Examples: Suspected viral gastroenteritis, non-specific abdominal pain → Patient instructed: "Return if fever develops, pain worsens, you can't keep fluids down, or new symptoms appear"
"Treat the patient, not the test result."
A physician weighs clinical judgment — how the patient looks, how the story fits, how the exam feels — alongside objective data. A normal CT does not rule out early appendicitis. An elevated WBC alone does not confirm infection. The full picture always guides the decision.
The best physicians are simultaneously running two parallel processes: pattern recognition (does this fit a familiar picture?) and hypothesis testing (what would prove or disprove each diagnosis?). That combination — experience and logic — is what separates clinical medicine from a checklist.