Abdominal Pain: A Symptom-Based Clinical Approach

Learn how to approach abdominal pain systematically with reasoning tips, key differentials, physical exam findings, mnemonics, and USMLE-style pearls.

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🚪 Doorway Case

A 27-year-old woman presents with lower abdominal pain for 2 days. She says, “I feel a dull ache in my lower belly that’s been getting worse.” Her vital signs are stable. No fever or vomiting.

💭 How do we think through this?

Let’s break down our approach by asking: Where is the pain? Is it acute or chronic? Is it localized or diffuse? What are the accompanying features?

🗺️ 6-Region Abdominal Map: Know the Organs

Dividing the abdomen into six zones helps identify potential organ-based causes:

Region	Key Organs
RUQ	Liver, Gallbladder, Duodenum, Right kidney, Colon
LUQ	Spleen, Stomach, Pancreas, Left kidney, Colon
Epigastric	Stomach, Pancreas, Aorta
RLQ	Appendix, Cecum, Right ovary & tube, Ureter
LLQ	Sigmoid colon, Left ovary & tube, Ureter
Suprapubic	Bladder, Uterus, Prostate (in males), Small bowel

🧠 Step-by-Step Reasoning

1. Location: Which quadrant or region is tender?
2. Onset & Duration: Sudden vs gradual onset → may suggest obstruction vs inflammation.
3. Character: Cramping? Sharp? Dull? → functional vs inflammatory
4. Radiation: To back (pancreas), shoulder (diaphragm), groin (renal colic)
5. Associated Symptoms: Fever, vomiting, diarrhea, dysuria, vaginal discharge?
6. Aggravating/Relieving: Food, movement, posture

❗ Red Flags in Abdominal Pain

• Sudden severe pain → consider perforation, AAA rupture, torsion
• Fever + localized pain → abscess, appendicitis, diverticulitis
• Hypotension or tachycardia → bleeding, sepsis, volume depletion
• Pregnancy + pain → always rule out ectopic pregnancy
• Bloody stool or melena → GI bleeding, ischemic colitis

🔍 Always consider urgent imaging or referral if any of these are present.

🧪 Key Differentials by Region

• RUQ: Cholecystitis, hepatitis, hepatic abscess, right pyelonephritis
• RLQ: Appendicitis, ovarian torsion, ectopic pregnancy, ileitis
• LUQ: Splenic infarct, gastritis, left pyelonephritis
• LLQ: Diverticulitis, ovarian cyst, sigmoid volvulus
• Epigastric: Pancreatitis, gastritis, MI, aortic aneurysm
• Suprapubic: UTI, cystitis, pelvic inflammatory disease, endometriosis

🧍‍♂️ Physical Exam Techniques

• Murphy’s sign: Suggests cholecystitis (Sens ~65%, Spec ~80%)
• McBurney’s point tenderness: Appendicitis
• Rovsing’s sign: RLQ pain with LLQ palpation
• Psoas sign: Pain with hip extension → retrocecal appendix
• Obturator sign: Pain with internal hip rotation
• Rebound tenderness & guarding: Suggest peritonitis
• CV angle tenderness: Pyelonephritis or stones

🧪 Appendicitis Tips (USMLE)

• Classically: Periumbilical pain → RLQ pain
• CT tip: Look 3 cm below the ileocecal valve, horizontal slices (~6 cuts)
• US findings: Non-compressible, >6mm appendix

🚺 Abdominal Pain in Female Patients: Never Forget

• Ask LMP (Last Menstrual Period)
• Always check hCG → ectopic pregnancy is life-threatening!
• Ask sexual history → PID, ovarian torsion
• Ask about contraception/IUD use

Pain + missed period + shoulder tip pain → Think ectopic pregnancy rupture

🔎 Traveler’s Diarrhea & Ileocecal Region

• Common ileocecal diseases: Appendicitis, Yersinia, Crohn’s, TB, Typhoid
• ETEC: #1 cause of watery diarrhea in travelers

🔑 USMLE-Style “One-Liner Diagnoses” (Tips)

• Watery + 2-day history + Mexico trip → ETEC
• Greasy foul-smelling stool + hiking → Giardia
• Bloody diarrhea + RUQ pain + no travel → Entamoeba + liver abscess
• Bloody diarrhea + undercooked chicken + GBS → Campylobacter
• Rapid-onset vomiting + wedding party → Norovirus

🔬 POCUS in Abdominal Pain

• RUQ: Gallbladder wall thickening, stones
• Pelvis: Free fluid in pouch of Douglas → ectopic pregnancy?
• Bladder volume, hydronephrosis for obstructive uropathy
• Abdominal aorta: Check for aneurysm (AAA)

📌 Clinical Pearls

• Always localize pain before diving into differentials
• Don’t forget to rule out pregnancy in reproductive-age females
• Ask about recent travel and dietary history
• Use bedside ultrasound early in undifferentiated cases
• Don’t rely solely on labs — the history and physical are key

💬 Useful Clinical Expressions

• “Where exactly is the pain? Can you point to it with one finger?”
• “Is it constant, or does it come and go?”
• “Does anything make it better or worse — eating, movement, position?”
• “Have you noticed any changes in your bowel habits?”
• “When was your last period? Any chance you could be pregnant?”

🔗 Related Learning

▶ How to Use Clinical Reasoning: A Step-by-Step Guide