What are the key components to evaluate and manage abdominal pain?

Evaluating Abdominal Pain: A Systematic Approach

When evaluating a patient with abdominal pain, begin by immediately assessing vital signs for concerning features (tachycardia, fever, hypotension, tachypnea), then characterize the pain by location, onset, duration, quality, and associated symptoms, followed by targeted laboratory testing and location-specific imaging—with ultrasonography for right upper quadrant pain and CT with contrast for lower quadrant or nonlocalized pain. 1, 2, 3

Immediate Assessment: Red Flags Requiring Urgent Action

Vital signs are your first priority and can identify life-threatening conditions before detailed history-taking:

• Tachycardia is the most sensitive early warning sign of surgical complications and should trigger urgent investigation, even before other symptoms develop 3
• Hypotension with sudden-onset pain suggests abdominal aortic aneurysm rupture (mortality >50%) or hemorrhage 4
• Fever, tachycardia, and tachypnea together predict serious complications including anastomotic leak, perforation, or sepsis 3
• Severe pain disproportionate to physical examination findings strongly suggests mesenteric ischemia and requires immediate surgical consultation 4, 3
• Signs of peritonitis (rigid abdomen, rebound tenderness, guarding) require urgent evaluation 2, 4, 3

Pain Characterization: The Critical Details

Location is your most useful starting point for narrowing the differential diagnosis and guiding imaging decisions 1, 3, 5:

• Onset and duration: Sudden onset suggests perforation, vascular catastrophe, or ruptured ectopic pregnancy; gradual onset suggests inflammatory processes 2, 5
• Quality: Colicky pain suggests obstruction; constant pain suggests inflammation or ischemia 5
• Radiation: Pain radiating to the back requires immediate evaluation for pancreatitis, aortic aneurysm, or mesenteric ischemia (mortality 30-90%) 4
• Aggravating/alleviating factors: Pain worse with movement suggests peritonitis; pain relieved by leaning forward suggests pancreatitis 2

Associated symptoms to specifically ask about:

• Nausea, vomiting, and abdominal distension suggest bowel obstruction 2, 3, 5
• Fever indicates infection or abscess 2, 4, 3
• Changes in bowel habits (diarrhea, constipation, rectal bleeding) 2
• Urinary symptoms 2

Physical Examination: Specific Findings to Document

Perform a complete abdominal examination systematically 2:

• Inspection: Look for distension, surgical scars, visible peristalsis 2
• Auscultation: Absent bowel sounds suggest ileus or perforation; high-pitched sounds suggest obstruction 5
• Percussion: Assess for tympany (obstruction) or dullness (ascites, mass) 2
• Palpation: Document location of tenderness, guarding, rebound tenderness, masses 2
• Murphy's sign: Pain with palpation of right upper quadrant during inspiration suggests cholecystitis 3

Laboratory Testing: Targeted Based on Clinical Suspicion

Essential initial tests:

• Complete blood count to evaluate for leukocytosis suggesting infection or inflammation 1, 2, 3
• Pregnancy test (beta-hCG) is mandatory for all women of reproductive age before proceeding to imaging 1, 2, 3
• C-reactive protein has higher sensitivity and specificity than white blood cell count for confirming surgical disease 2, 3
• Metabolic panel, liver function tests, amylase, and lipase for suspected hepatobiliary disease or pancreatitis 2, 3

Additional tests based on clinical suspicion:

• Elevated lactate suggests ischemia or sepsis (though normal levels don't exclude early ischemia) 2, 4, 3
• Procalcitonin for assessing inflammatory response in suspected sepsis 3
• Renal function tests (creatinine, BUN) 2

Imaging Strategy: Location-Specific Approach

The American College of Radiology Appropriateness Criteria provide clear guidance based on pain location 1:

Right Upper Quadrant Pain

• Ultrasonography is the initial imaging test of choice (sensitivity 81%, specificity 83% for cholecystitis) 1, 2, 3

Right Lower Quadrant Pain

• CT with IV contrast is recommended (sensitivity >95% for appendicitis) 1, 2, 3
• Consider ultrasound first in young patients to reduce radiation exposure 1, 3

Left Lower Quadrant Pain

• CT with IV contrast is recommended for suspected diverticulitis 1, 2, 3

Nonlocalized or Diffuse Abdominal Pain

• CT of abdomen and pelvis with IV contrast is the preferred initial imaging (alters diagnosis in 49% of patients and changes management in 42% of cases) 1, 2, 4
• CT provides comprehensive evaluation of all abdominal organs in a single examination 4

Suspected Kidney Stones

• Non-contrast CT of abdomen and pelvis 2, 3

Pain Radiating to Back

• CT of abdomen and pelvis with IV contrast to evaluate for pancreatitis, aortic pathology, or mesenteric ischemia 4
• CT angiography is the gold standard for diagnosing mesenteric ischemia and aortic pathology 4

Important caveat: Conventional radiography has limited diagnostic value and should not be routinely used, except for suspected bowel obstruction 1, 2, 4

Special Population Considerations

Women of Reproductive Age

• Always consider gynecologic causes: ectopic pregnancy, ovarian torsion, pelvic inflammatory disease 1, 2, 3
• Pregnancy test is mandatory before imaging 1, 2, 3

Pregnant Patients

• Ultrasound should be first-line imaging 1, 2
• MRI (not CT) if additional imaging needed to avoid radiation exposure 1, 2
• Appendicitis is the most common cause requiring emergent surgery in pregnancy, but pain location may not correlate reliably 1

Elderly Patients

• Symptoms are often atypical and laboratory tests may be normal despite serious pathology 1, 2, 3
• Higher likelihood of malignancy, diverticulitis, and vascular causes 3
• Require more thorough evaluation even with normal initial testing 3

Immunocompromised/Neutropenic Patients

• Signs of abdominal sepsis may be masked and diagnosis may be delayed 1, 2
• CT with IV contrast is usually appropriate to evaluate for atypical and opportunistic infections 1

Post-Bariatric Surgery Patients

• Often present with atypical symptoms 2, 3
• Tachycardia is the most critical warning sign 2, 3
• Classic peritoneal signs often absent; consider internal herniation even with normal lactate 3

Postoperative Patients

• CT of abdomen and pelvis with IV contrast to evaluate for postoperative abscesses, leaks, or hemorrhage 1

Common Pitfalls to Avoid

• Do not rely solely on laboratory tests without appropriate imaging, as many conditions require imaging for definitive diagnosis 2
• Do not delay surgical consultation in patients with peritonitis or signs of septic shock 2
• Do not overlook gynecological causes in women of reproductive age 2
• Do not assume negative ultrasound rules out severe pathology—proceed to CT if clinical suspicion persists 4
• Do not ignore tachycardia as an early warning sign, even before other symptoms develop 2, 3
• Do not forget pregnancy testing in women of reproductive age before proceeding to CT 2, 4
• Avoid overusing CT scans in young patients to minimize unnecessary radiation exposure 1, 3
• Do not routinely use conventional radiography for diagnosis, as it has limited diagnostic value 1, 2, 4

Disposition and Management Decisions

Hemodynamically unstable patients require:

• Immediate resuscitation with crystalloid IV fluids 2
• Urgent surgical consultation 2

Patients requiring hospital admission:

• Severe pain, hemodynamic instability, peritoneal signs, or suspected surgical conditions 2

Antibiotic considerations:

• Should not be routinely administered but are indicated for suspected infection or intra-abdominal abscess 2
• For intra-abdominal abscesses >3cm, consider percutaneous drainage with antimicrobial therapy 2
• Small abscesses (<3cm) may be treated with IV antibiotics alone 2