Which preoperative laboratory tests should be obtained for an adult with a suspected abdominal or groin hernia, including pregnancy testing for women of child‑bearing age, diabetes screening, evaluation for incarceration or strangulation, assessment of liver disease or coagulopathy, review of anticoagulant therapy, and consideration of cardiovascular risk?

Preoperative Laboratory Testing for Hernia Evaluation

For routine elective hernia repair in otherwise healthy adults, minimal laboratory testing is required—typically only basic screening labs if indicated by patient comorbidities, with pregnancy testing mandatory for women of childbearing age.

Essential Laboratory Tests

Pregnancy Testing

• All women of childbearing age must undergo pregnancy testing before hernia repair 1
• Pregnancy significantly increases intraabdominal pressure and is associated with increased hernia recurrence risk (adjusted OR 1.73) 1
• Emergency hernia surgery during pregnancy carries substantial risks that must be avoided through preoperative screening 1

Basic Screening Labs (Selective, Based on Clinical Context)

For patients with specific risk factors or emergency presentations:

• Complete blood count (CBC): Obtain when evaluating for incarceration/strangulation to assess for leukocytosis (WBC >10,000/mm³) which may indicate peritonitis or ischemia, though sensitivity is relatively low 2
• Lactate level: Critical in emergency settings—elevated lactate (≥2.0 mmol/L) predicts non-viable bowel strangulation and necessitates urgent surgical intervention 3
• C-reactive protein (CRP): CRP >75 mg/L suggests peritonitis, though this has limited sensitivity and specificity 2
• Electrolytes and BUN/creatinine: Essential to assess for dehydration and acute kidney injury, particularly in patients with incarcerated hernias who may have prolonged symptoms 2

Comorbidity-Specific Testing

Diabetes Screening

• Obtain hemoglobin A1c or fasting glucose in patients with known diabetes or risk factors 4
• Diabetes increases risk of 30-day postoperative complications (OR 1.35) following hernia surgery 4
• Complicated diabetes (with secondary manifestations) carries even higher risk and warrants optimization before elective repair 4
• Diabetes does not increase long-term recurrence risk, so should not delay necessary surgery 4

Coagulopathy and Anticoagulation Assessment

• Coagulation profile (PT/INR, aPTT) is mandatory for patients on anticoagulant therapy or with known liver disease 5
• Patients on anticoagulants or with coagulopathy have significantly increased bleeding risk (3.9% vs 1.6%, OR 2.0) and reoperation rates (2.4% vs 1.0%) 5
• Document all antiplatelet agents (aspirin, clopidogrel) and anticoagulants (warfarin, DOACs) with specific plans for perioperative management 5
• Consider laparoscopic approach when feasible, as it reduces bleeding complications in this higher-risk population 5

Liver Disease Evaluation

• Liver function tests (AST, ALT, bilirubin, albumin) if clinical suspicion of hepatic dysfunction 2
• Coagulopathy from liver disease substantially increases surgical bleeding risk 5

Emergency Presentation: Additional Urgent Labs

When incarceration or strangulation is suspected:

• Immediate lactate measurement: Values ≥2.0 mmol/L indicate high probability of bowel ischemia requiring emergency surgery 3
• CBC with differential: Leukocytosis with left shift suggests ischemia, though normal values cannot exclude it 2
• Comprehensive metabolic panel: Assess electrolyte disturbances and renal function from dehydration 2
• Elevated CRP and lactate together strengthen the case for emergency exploration, though their absence does not rule out strangulation 2

Cardiovascular Risk Assessment

ASA Classification Documentation

• ASA score must be documented as it directly correlates with adverse events 6
• Emergency operations carry 3-fold increased risk of cardiovascular events (OR 3.1 in men, 2.8 in women) 6
• Regional anesthesia increases cardiovascular morbidity compared to local anesthesia (OR 1.4) 6

Age-Related Considerations

• Patients >85 years have dramatically increased delirium risk (OR 6.24) and require cognitive screening 2
• Advanced age alone warrants more comprehensive preoperative assessment including cardiac evaluation 6

What NOT to Routinely Order

Avoid unnecessary testing in healthy patients undergoing elective repair:

• Plain radiographs are not indicated for hernia diagnosis—physical examination is sufficient 7
• Imaging (ultrasound or CT) is reserved for diagnostic uncertainty, obesity, or suspected complications—not routine preoperative workup 7
• Extensive metabolic panels in asymptomatic patients without comorbidities add no value 2

Critical Clinical Pitfalls

• Never delay pregnancy testing in women of reproductive age—unrecognized pregnancy dramatically alters surgical risk-benefit analysis 1
• Do not dismiss normal lactate in a patient with clinical signs of strangulation—sensitivity is imperfect and clinical judgment supersedes laboratory values 3
• Emergency hernia repairs have substantially higher complication rates—optimize medical comorbidities when time permits, but do not delay surgery for bowel ischemia 6
• Bilateral hernias and sliding hernias approximately double the risk of severe surgical complications (OR 1.9 and 2.2 respectively), warranting heightened perioperative vigilance 6