What is the initial workup and management for a patient with suspected intraabdominal infection?

Workup for Intraabdominal Infection

Begin with routine history, physical examination, and laboratory studies to identify patients requiring further management, then obtain CT imaging for those not proceeding immediately to surgery, while simultaneously initiating fluid resuscitation and antibiotics. 1

Initial Clinical Assessment

History and Physical Examination:

• Look for rapid-onset abdominal pain, gastrointestinal dysfunction (nausea, vomiting, bloating, obstipation), and signs of inflammation (fever, tachycardia, tachypnea, abdominal tenderness) 1
• In patients with unreliable examination findings (obtunded mental status, spinal cord injury, immunosuppression), consider intraabdominal infection if infection from undetermined source is present 1
• Assess severity using clinical judgment incorporating patient age, physiologic derangements, and comorbidities—this is as accurate as numerical scoring systems 1

Laboratory Studies:

• Obtain routine laboratory tests as part of initial evaluation 1
• Blood cultures are NOT routinely recommended for community-acquired infections, but obtain them if patient appears clinically toxic or is immunocompromised 1
• For higher-risk patients (prior antibiotic exposure, healthcare-associated infection), obtain cultures from the infection site to guide therapy 1

Imaging Strategy

CT Scan is the imaging modality of choice for adult patients not undergoing immediate laparotomy to determine presence and source of infection 1, 2

Skip imaging entirely in patients with obvious signs of diffuse peritonitis who require immediate surgical intervention—do not delay surgery for diagnostic imaging 1, 2

Immediate Resuscitation (Concurrent with Workup)

Fluid Resuscitation:

• Begin rapid intravascular volume restoration immediately upon recognition of hypotension in septic shock 1, 3, 2
• Start intravenous fluids when intraabdominal infection is first suspected, even without evidence of volume depletion 1, 3, 2
• Continue resuscitation measures during surgical intervention if needed—do not delay surgery for complete stabilization 1, 3, 4

Antimicrobial Therapy:

• Administer antibiotics within 1 hour of recognizing septic shock, as every hour of delay increases mortality 1, 3
• For patients without septic shock, start antibiotics in the emergency department within 8 hours of presentation 1, 3
• Maintain satisfactory antimicrobial drug levels during source control procedures, which may require additional dosing before the procedure 1, 4

Risk Stratification for Treatment Planning

Clinical factors predicting poor outcomes include: 1, 2

• Delay in initial intervention (>24 hours)
• High severity of illness (APACHE II score ≥15)
• Advanced age
• Comorbidity and organ dysfunction
• Low albumin level
• Diffuse peritonitis
• Presence of malignancy

Source Control Planning

Emergency surgery is required immediately for patients with diffuse peritonitis, even while continuing resuscitation 1, 3, 2, 4

Percutaneous drainage is preferable to surgical drainage for well-localized abscesses when feasible 1, 2

Intervention may be delayed up to 24 hours in hemodynamically stable patients without organ failure if appropriate antimicrobials are given and close monitoring is provided 1, 2

Common Pitfalls to Avoid

• Never delay antibiotics to obtain cultures in septic shock—every hour of delay increases mortality 3
• Never delay surgery in diffuse peritonitis waiting for "complete" resuscitation—operate while continuing resuscitation 3, 4
• Never skip imaging in stable patients—CT is essential to identify source and guide intervention unless diffuse peritonitis is obvious 1, 2
• Do not obtain routine blood cultures for community-acquired infections—they rarely change management 1