What is the evaluation process for abdominal pain to determine the need for surgical intervention?

Surgical Evaluation of Abdominal Pain

Immediate Assessment: Hemodynamic Stability First

In any patient with acute abdominal pain, immediately assess hemodynamic stability—if the patient is hypotensive (systolic BP <90 mmHg) or shows signs of shock, perform bedside ultrasound (FAST exam) as the initial diagnostic test to identify need for emergent laparotomy. 1

Hemodynamically Unstable Patients

• Bedside ultrasound should be the initial diagnostic modality in hemodynamically unstable patients with acute abdominal pain to rapidly identify free fluid, solid organ injury, or other surgical emergencies requiring immediate laparotomy 1
• Ultrasound can be performed rapidly at bedside, is inexpensive, has no radiation risk, and does not require patient transport 1
• If ultrasound is unavailable or non-diagnostic and the patient remains unstable, proceed directly to emergency laparotomy rather than delaying for CT 1

Life-Threatening Conditions Requiring Immediate Surgical Consultation

Pain Out of Proportion to Physical Findings

• This is the hallmark of acute mesenteric ischemia and mandates immediate CTA and surgical consultation 2, 3
• Acute mesenteric ischemia carries 50-80% mortality if untreated, with mortality increasing every hour of delay 2, 3
• Early laboratory findings show leukocytosis, lactic acidosis, elevated amylase, and occult blood in stool 2
• Suspect this particularly in elderly patients with atrial fibrillation, recent MI, or cardiovascular disease 2

Peritoneal Signs (Rigidity, Guarding, Rebound)

• Abdominal rigidity and peritoneal signs indicate peritonitis requiring immediate surgical evaluation for perforated viscus 2, 3
• Do not delay surgical consultation for imaging if overt peritonitis is present 3
• Broad-spectrum antibiotics covering gram-negatives and anaerobes (ceftriaxone + metronidazole or amoxicillin/clavulanate) should be started immediately while arranging surgery 3

Hemodynamically Stable Patients: Risk Stratification by Location

Right Lower Quadrant Pain

• Use clinical findings to risk-stratify patients and guide imaging decisions 1
• CT abdomen/pelvis with IV contrast is the definitive imaging modality with sensitivity >95% for appendicitis 1, 3
• Migratory pain from periumbilical to RLQ strongly suggests appendicitis and warrants immediate CT 3
• Preoperative CT reduces negative appendectomy rates from 18.7% to 2.6% in low-probability patients 1
• In patients with nonappendiceal CT findings (diverticulitis, obstruction, ileocecitis), 41% require hospitalization and 22% undergo surgical or image-guided intervention 1

Right Upper Quadrant Pain

• Ultrasound is the first-line imaging modality with 81% sensitivity and 83% specificity for cholecystitis 3, 4
• If ultrasound is non-diagnostic and symptoms persist, proceed to CT or MRI 5

Nonlocalized or Diffuse Abdominal Pain

• CT abdomen/pelvis with IV contrast is the preferred imaging for broad differential diagnosis 1, 3
• CT changes the leading diagnosis in 49% of cases, alters admission status in 24%, and changes surgical plans in 25% 1
• Most institutions no longer use oral contrast routinely due to delays without clear diagnostic advantage 1
• Consider acute cholecystitis (9-11%), small bowel obstruction (4-5%), pancreatitis, diverticulitis, and perforated peptic ulcer 2

Blunt Abdominal Trauma

• Bedside ultrasound should be the initial diagnostic modality in unstable trauma patients 1
• CT is preferred in hemodynamically stable trauma patients 1
• DPL has 96% sensitivity but 24% non-therapeutic laparotomy rate and 1.5% complication rate 1

Essential Laboratory Workup

• Obtain CBC, basic metabolic panel, lactate, CRP, liver function tests, and lipase immediately 3
• Elevated lactate is critical for detecting bowel ischemia, severe sepsis, or acute mesenteric ischemia 3
• WBC >10,000/mm³ has positive likelihood ratio of 2.47 for appendicitis; WBC >15,000/mm³ has positive likelihood ratio of 3.47 1
• Pregnancy test is mandatory in all women of reproductive age before any imaging—this is non-negotiable 2, 3, 5

Special Population Considerations

Elderly Patients

• Imaging is especially critical as laboratory tests may be normal despite serious infection 2
• Typical signs of abdominal sepsis may be masked, leading to delayed diagnosis 1, 2
• Lower threshold for CT imaging and surgical consultation 2

Immunocompromised/Neutropenic Patients

• Typical signs of abdominal sepsis are masked with high mortality rates 1, 2
• Laboratory values may be normal despite serious infection 2
• Maintain very low threshold for imaging and surgical consultation 1, 2

Critical Pitfalls to Avoid

• Never discharge patients with "pain out of proportion to exam" without CTA—this is acute mesenteric ischemia until proven otherwise 2, 3
• Never delay analgesia—pain medication does not mask symptoms or impair diagnostic accuracy 3
• Never rely solely on clinical exam or labs without imaging when diagnosis is unclear—imaging changes management in 51% of cases 3
• Never miss the window in appendicitis—delays beyond 24 hours increase perforation risk 3
• Never overlook gynecologic emergencies (ectopic pregnancy, ovarian torsion, PID) in women of reproductive age 3
• Never assume normal labs exclude serious pathology in elderly or immunocompromised patients 2

Disposition Algorithm

Immediate surgical consultation if:

• Hemodynamic instability despite resuscitation 1, 3
• Peritoneal signs (rigidity, guarding, rebound) 2, 3
• Pain out of proportion to exam 2, 3
• Free air on imaging 2
• CT findings of perforation, ischemia, or obstruction requiring intervention 1, 3

Admit to hospital if:

• Hemodynamic instability 3
• Peritoneal signs 3
• Suspected surgical conditions pending further evaluation 3

Discharge with 24-hour follow-up if:

• Imaging negative and alternative benign diagnosis confirmed 3
• Approximately 30% of ED abdominal pain cases remain undiagnosed initially 3