Pathophysiology of Abdominal Pain

1. Visceral: distension of hollow organs or capsular stretch of solid organs.
2. Somatic: parietal peritoneal irritation
3. Referred
   • Extra-abdominopelvic
     • Epigastric: inferior MI
     • Pelvic: hip
     • Abdominal: lower lobe pneumonia/infarction
   • Abdominopelvic
     • Shoulder: diaphragmatic irritation (ex. perforated duodenal ulcer, splenic pathology)
     • Mid-back: aortopathy, pancreatitis
     • Flank: renal pathology
     • Low back: uterus, rectum

Concerning Historical Features

• Elderly: increased probability for severe disease with poor clinical diagnostic accuracy
• Immunocompromised: HIV/AIDS, uncontrolled diabetes, chronic liver disease, chemotherapy, other immunosuppression
• Pain preceding nausea/vomiting: increased likelihood of surgical process
• Abrupt onset, duration <48h, constant timing
• Prior abdominal surgical history: consider bowel obstruction
• No prior episodes of similar pain
• Recent antibiotic or steroid use: may mask signs of infection
• Cardiac risk factors (HTN, vascular disease, atrial fibrillation: increased risk for mesenteric ischemia or aortic aneurysm
• Heavy NSAID use or anticoagulation: increase concern for gastrointestinal bleeding

Imaging

• Plain film reserved for those who would otherwise not undergo CT. XR abdomen for bowel obstruction or radiopaque foreign body.
• CT abdomen/pelvis with IV contrast, particularly if elderly or immunocompromised.
• Ultrasound preferred for hepatobiliary pathology
• Bedside ultrasound for identification of IUP, free intraperitoneal fluid, cholecystitis, CBD dilation, ascites, hydronephrosis, aortopathy, volume status.

Causes of Abdominal Pain

References

1. Budhram, G., & Bengiamin, R. (2013). Abdominal Pain. In Rosen’s Emergency Medicine – Concepts and Clinical Practice (8th ed., Vol. 1, pp. 223-231). Elsevier Health Sciences.