What lab workup is indicated for suspected abdominal compartment syndrome?

Laboratory Workup for Suspected Abdominal Compartment Syndrome

In patients with suspected abdominal compartment syndrome, a complete blood count, comprehensive metabolic panel, serum lactate, and inflammatory markers (C-reactive protein, procalcitonin) should be obtained to assess organ dysfunction and guide management decisions. 1

Essential Laboratory Tests

Primary Laboratory Panel

• Complete Blood Count (CBC)

  • Evaluates for leukocytosis (marker of inflammation/infection)
  • Assesses for hemoconcentration or anemia (related to fluid status or bleeding)

• Comprehensive Metabolic Panel

  • Serum creatinine and BUN to assess renal function (kidney dysfunction is an early sign of ACS) 2
  • Liver function tests to evaluate hepatic perfusion
  • Electrolytes to identify imbalances from organ dysfunction

• Serum Lactate

  • Critical marker of tissue hypoperfusion and ischemia
  • Elevated levels suggest compromised abdominal organ perfusion 1

• Inflammatory Markers

  • C-reactive protein (CRP)
  • Procalcitonin (PCT) - particularly useful in cases with suspected infectious etiology 1

Additional Recommended Tests

• Arterial Blood Gas

  • Evaluates acid-base status
  • Identifies metabolic acidosis (common in ACS)
  • Assesses respiratory function (often compromised in ACS)

• Coagulation Profile

  • PT/INR, PTT
  • Important if surgical intervention may be needed 1

Laboratory Findings in ACS

Renal Dysfunction Markers

• Rising creatinine despite adequate fluid resuscitation
• Decreased urine output (oliguria or anuria)
• Elevated BUN-to-creatinine ratio

Metabolic Derangements

• Metabolic acidosis (decreased serum bicarbonate)
• Elevated lactate levels correlate with severity of organ hypoperfusion 1
• Electrolyte abnormalities (particularly hyperkalemia in severe cases)

Diagnostic Algorithm

1. Initial Assessment:

   • Measure intra-abdominal pressure (IAP) via intravesical (bladder) pressure measurement (gold standard) 1, 3
   • IAP >12 mmHg indicates intra-abdominal hypertension
   • IAP >20 mmHg with new organ dysfunction defines abdominal compartment syndrome 4

2. Laboratory Evaluation:

   • Order complete laboratory panel as outlined above
   • Repeat measurements every 4-6 hours in critically ill patients at risk for ACS

3. Correlation with Clinical Status:

   • Monitor for worsening laboratory values despite appropriate resuscitation
   • Pay particular attention to rising creatinine, lactate, and worsening acidosis

Clinical Pearls and Pitfalls

• Key Pearl: Renal dysfunction is often the earliest laboratory indicator of ACS, manifesting as rising creatinine and decreasing urine output 2

• Common Pitfall: Attributing laboratory abnormalities solely to other conditions (sepsis, hypovolemia) without considering ACS as a contributing factor

• Important Consideration: Laboratory values should be interpreted in conjunction with IAP measurements and clinical status - no single laboratory test can diagnose ACS

• Warning Sign: Rapidly rising lactate levels in a patient with known risk factors for ACS should prompt immediate IAP measurement and consideration of decompressive intervention 1

Laboratory findings must be interpreted in the context of the patient's clinical condition and IAP measurements. While laboratory tests are essential for evaluating organ dysfunction, the definitive diagnosis of ACS requires both elevated IAP (>20 mmHg) and evidence of new organ dysfunction 3.