Acute Abdominal Pain

Jacob Lee

This chapter aims to guide history taking and evaluation of acute abdominal pain and is not meant to be exhaustive. Treatment is based on the findings and is beyond the scope of this chapter.

History

  • Location: radiation, quality, triggers and timing (constant +/- waxing and waning vs intermittent).
  • Rate of onset, relationship to eating and/or bowel movements, prior abdominal surgeries, LMP; sexual history, urinary symptoms, constitutional symptoms.
  • Ingestion: illicit substances, alcohol, medications (e.g., NSAIDs, antibiotics), food.
  • Nausea: onset, relationship to pain, food, etc. 
  • Vomiting: regurgitated food, bile, blood, coffee-ground material.
  • Additional ROS can help inform a syndromic or systemic cause.

Organ system involvement based on localization

Note: Localizations may overlap, and many organs can cause referred pain.

  • Epigastric: esophagus, stomach, small bowel, pancreas, cardiac.
  • RUQ: hepatobiliary, pulmonary.
  • LUQ: spleen and colon, pulmonary.
  • Periumbilical: vascular, small bowel, colon.
  • RLQ: renal (flank), appendix, colon ovaries.
  • LLQ: renal (flank), colon, ovaries.
  • Suprapubic: uterus, bladder, colon, testicles.

Expanded Differential Diagnosis

  • Esophagus: esophagitis (GERD, infectious, pill), spasm/dysmotility, tear rupture, food impaction 
  • Stomach: gastritis/gastroenteritis, gastroparesis 
  • Pancreas: pancreatitis, infected pseudocyst 
  • Bowel: gastroenteritis, bowel obstruction/ileus, volvulus, IBD, mesenteric ischemia, hernias, PUD, perforation, diverticulitis, malabsorption (Celiac, lactose intolerance), colitis, toxic megacolon, Ogilvie syndrome, typhlitis, IBS 
  • Liver: Fitz-Hugh-Curtis, Budd-Chiari, PVT, malignancy 
  • Gallbladder/bile: (acalculous) cholecystitis, choledocholithiasis, cholangitis, sphincter of Oddi dysfunction 
  • Spleen: splenomegaly, splenic rupture 
  • Appendix: appendicitis 
  • Kidneys: nephrolithiasis, pyelonephritis, perinephric abscess, infarction 
  • Vasculature: mesenteric ischemia, AAA rupture or leak, Type B aortic dissection, vasculitis, infarctions of any of the organ systems mentioned 
  • Reproductive Tract: 
    • Female: ectopic pregnancy, tubo-ovarian abscess, ovarian cyst/torsion, ovulatory pain (Mittelschmerz), PID, endometriosis, fibroids 
    • Male: torsion, strangulated/incarcerated inguinal hernias
  • Pulmonary: pneumonia, parapneumonic effusion/empyema 
  • Cardiac: MI, pericarditis, myocarditis 
  • Infectious: SBP, CMV, EBV, food-borne pathogens, parasites/helminths, abscesses 
  • Hematologic: AIP, Familial Mediterranean Fever 
  • Endocrine: adrenal insufficiency/crisis, DKA, hypercalcemia 
  • Superficial (Skin/MSK): shingles, muscle strain, rib fractures 
  • Autoimmune/Rheumatologic/Allergic: angioedema, vasculitis, SLE 
  • Other: GI bleeds (uncommon), abdominal compartment syndrome, poisonings/toxic syndromes

Functional abdominal pain: diagnosis of exclusion based on negative workup of the above

  • Features: recurrent pain that lacks structural or biochemical abnormalities. Often associated with altered bowel habits, meal-related symptoms, and psych comorbidities.

Workup for acute abdominal pain

  • Initial lab workup: CBC with diff, BMP, HFP 
  • Additional lab considerations: lipase, UA +/- culture, lactic acid, coags, beta-hCG, blood cultures, stool studies 
  • Imaging: 
    • Ultrasound: great for renal, hepatic biliary, ovarian, ureteral pathology 
      • Add dopplers for transplants and for ischemic eval 
    • CT - generally a CTAP with contrast is the preferred choice. Instances where it is not: 
      • If concern for perforation: Upright CXR or CT A/P (preferred) 
      • Esophagus: CT CAP with contrast 
      • Cirrhosis/HCC: CT triple phase 
      • Crohn's: CT enterography 
      • Vascular: CTA 
      • Kidney stones: CTAP without contrast
  • Consulting: case by case basis, but instances where you will need a consultant to advance care: 
    • Transplant - always 
    • Suspected GIB - endoscopy 
    • Biliary Obstruction - MRCP vs ERCP with possible stent placement 
    • Mass / Abscess - biopsy or drainage
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