Laboratory Tests for Patients with Abdominal Pain

Initial Laboratory Evaluation

A comprehensive laboratory workup for patients presenting with abdominal pain should include complete blood count, comprehensive metabolic panel, urinalysis, serum lipase, and pregnancy testing in women of reproductive age 1
Complete blood count (CBC) is essential to assess for leukocytosis, which may indicate infection or inflammation 1
Comprehensive metabolic panel (CMP) including liver function tests should be ordered to evaluate hepatobiliary pathology and assess organ function 1
Urinalysis is recommended to evaluate for urinary tract infection or nephrolithiasis 1
Serum lipase is more specific than amylase for diagnosing pancreatitis and should be included in the initial workup 1
Beta-human chorionic gonadotropin (β-hCG) testing is mandatory in all women of reproductive age to rule out pregnancy-related conditions including ectopic pregnancy 1

For patients with right upper quadrant pain, liver function tests (ALT, AST, alkaline phosphatase, bilirubin) and hepatobiliary markers are particularly important 1
Ultrasonography is the initial imaging test of choice for patients with right upper quadrant pain 2
For patients with lower quadrant pain, complete blood count with differential is recommended to assess for appendicitis or diverticulitis 1
Computed tomography (CT) is recommended for evaluating right or left lower quadrant pain 2
For patients with diffuse abdominal pain, lactate and D-dimer may be helpful if mesenteric ischemia is suspected 1
CT with intravenous contrast is often the preferred imaging option for generalized abdominal pain 3

In patients with fever and abdominal pain, blood cultures should be considered, especially if sepsis is suspected 1
For immunocompromised patients with abdominal pain, a more extensive workup may be necessary 1
In patients with suspected pancreatitis, consider using elevated cutoff levels for pancreatic enzymes to improve diagnostic accuracy 1

Failing to obtain pregnancy testing in women of reproductive age before proceeding with imaging studies can lead to delayed diagnosis of pregnancy-related conditions 1
Conventional radiography has limited diagnostic value in the assessment of most patients with abdominal pain and should not be routinely ordered 2

If initial laboratory workup is inconclusive but clinical suspicion remains high for serious pathology, imaging studies should be considered based on the location of pain 1
The American College of Radiology has developed clinical guidelines (Appropriateness Criteria) based on the location of abdominal pain to help physicians choose the most appropriate imaging study 2
For suspected mesenteric ischemia, additional markers such as lactate and D-dimer may be helpful, though they lack specificity 1