What is the initial workup and management for a patient presenting with abdominal pain?

Initial Workup for Abdominal Pain

Begin with immediate vital sign assessment and proceed systematically through laboratory testing and location-based imaging, with CT scan being the preferred modality for most presentations except right upper quadrant pain where ultrasound is first-line. 1, 2

Immediate Assessment

Vital Signs and Hemodynamic Status

• Check for tachycardia, fever, hypotension, respiratory distress, or decreased urine output—these are alarming signs requiring immediate intervention and surgical consultation 1
• Hemodynamically unstable patients require immediate IV fluid resuscitation with crystalloid solutions and urgent surgical consultation 1, 3

Pain Characterization

• Document location, onset (acute vs gradual), duration, quality (sharp, cramping, burning), radiation pattern, and aggravating/alleviating factors 1, 2
• Assess associated symptoms: fever (infection/inflammation), nausea, vomiting, diarrhea, constipation, or changes in bowel habits 2

Physical Examination

• Perform systematic abdominal examination: inspection for distension, auscultation for bowel sounds, percussion for tympany or dullness, and palpation for tenderness, guarding, or rebound 1, 2
• Peritoneal signs (guarding, rigidity, rebound tenderness) indicate need for emergency surgical exploration 1

Mandatory Laboratory Tests

Core Laboratory Panel

• Complete blood count to evaluate leukocytosis (infection/inflammation) or anemia 2, 3
• C-reactive protein as an inflammation marker—may be fundamental in differential diagnosis 4, 2
• Basic metabolic panel including serum electrolytes, creatinine, and blood urea nitrogen for renal function and electrolyte abnormalities 2, 3
• Liver function tests and hepatobiliary markers especially for right upper quadrant pain 1, 2
• Pregnancy test is mandatory for all women of reproductive age before proceeding to imaging 1, 2

Additional Tests Based on Clinical Suspicion

• Lactate level if bowel ischemia or severe sepsis is suspected 1, 3
• Lipase if pancreatitis is considered 5
• Urinalysis to evaluate for urinary tract infection or hematuria 5
• Stool studies and C. difficile toxin if diarrhea is present 4, 2

Imaging Strategy Based on Pain Location

Right Upper Quadrant Pain

• Ultrasonography is the initial imaging test of choice with 81% sensitivity and 83% specificity for cholecystitis 1, 2

Right Lower Quadrant Pain

• CT scan with contrast media is recommended, with sensitivity over 95% for appendicitis 1, 2

Left Lower Quadrant Pain

• CT scan with contrast media for suspected diverticulitis 1, 2

Diffuse or Nonlocalized Abdominal Pain

• CT scan of abdomen and pelvis with IV contrast is the preferred imaging modality 1, 2

Pelvic Pain

• CT of abdomen and pelvis with contrast is most appropriate 1

Suspected Kidney Stones

• Non-contrast CT of abdomen and pelvis 1

Important Imaging Considerations

• Plain radiographs have limited diagnostic value and should not be routinely used except for suspected bowel obstruction 1, 2
• Point-of-care ultrasound may be useful when expertise exists for specific conditions like cholecystitis, urolithiasis, or appendicitis 2, 5

Special Population Considerations

Women of Reproductive Age

• Always consider gynecologic conditions: ectopic pregnancy, ovarian torsion, pelvic inflammatory disease 1, 5
• Pregnancy test is non-negotiable before imaging 1, 2

Pregnant Patients

• Ultrasound should be first-line imaging 1, 2
• MRI is preferred over CT if additional imaging is needed 1, 2

Elderly Patients

• Often present with atypical symptoms and may have normal laboratory tests despite serious pathology 1, 2
• Maintain high index of suspicion despite unremarkable initial findings 2

Immunocompromised Patients

• Clinical signs may not be reliable; the greater the immunocompromise, the less reliable the clinical presentation 4
• Laboratory tests may not accurately reflect severity of clinical condition 4
• Contrast-enhanced CT scan is the most reliable exam whenever feasible 4
• Consider opportunistic infections and note that immunosuppressive medications may mask inflammatory signs 3
• Document current medications, especially steroids, immunomodulators, or anti-TNF-α agents which increase infection risk 3

Management Decisions

Indications for Immediate Surgical Consultation

• Peritoneal signs (guarding, rigidity, rebound tenderness) 1
• Signs of perforation or free air on imaging 1, 3
• Hemodynamic instability despite resuscitation 1, 3
• Septic shock 1
• Bowel obstruction 3

Medical Management Approach

• Antibiotics should not be routinely administered—only indicated for suspected infection or intra-abdominal abscess 4, 1
• For suspected intra-abdominal infection, use antibiotics covering Gram-negative bacteria, anaerobes, Gram-positive streptococci, and facultative bacilli 4
• Intra-abdominal abscesses >3cm require percutaneous drainage with antimicrobial therapy 1
• Small abscesses (<3cm) without fistula, not on steroids, may respond to antibiotics alone though with high recurrence rates 4
• Initiate venous thromboembolism prophylaxis with low molecular weight heparin early, especially in inflammatory conditions 4, 3
• Correct electrolyte abnormalities and anemia 4

Disposition Decisions

• Admit patients with: severe pain, hemodynamic instability, peritoneal signs, or suspected surgical conditions 1

Critical Pitfalls to Avoid

• Do not rely solely on laboratory tests without appropriate imaging—many conditions require imaging for definitive diagnosis 1, 2
• Do not delay surgical consultation in patients with peritonitis or signs of septic shock 1
• Do not overlook gynecological causes in women of reproductive age 1
• Do not assume normal presentation in elderly patients—they frequently present atypically 1, 2
• Do not overuse CT scans in young patients unnecessarily, increasing radiation exposure 1
• Do not perform repetitive testing once functional pain is established 6