What are the necessary stat labs for an adult patient presenting with right upper quadrant (RUQ) and right flank pain, with a potential history of abdominal or renal issues?

Stat Laboratory Workup for RUQ and Right Flank Pain

Order a comprehensive metabolic panel (including liver function tests), complete blood count, lipase/amylase, urinalysis, and pregnancy test (for women of reproductive age) immediately. 1, 2

Essential First-Line Laboratory Tests

The following labs should be ordered stat for all patients presenting with RUQ and right flank pain:

Core Laboratory Panel

• Complete Blood Count (CBC) to assess for leukocytosis indicating infection, inflammation, or acute cholecystitis 1, 2
• Comprehensive Metabolic Panel including:
  • Liver function tests (ALT, AST, alkaline phosphatase, GGT, bilirubin) to evaluate hepatobiliary pathology 1, 2
  • Renal function tests (BUN, creatinine) given the right flank pain component suggesting possible renal pathology 2
• Pancreatic enzymes (amylase and lipase) to rule out pancreatitis, which can present with RUQ pain 2
• Urinalysis to evaluate for renal stones or urinary tract infection, particularly important given the flank pain component 2
• Pregnancy test for all women of reproductive age to exclude ectopic pregnancy before any imaging 1, 2

Additional Tests Based on Clinical Suspicion

If Biliary Pathology Suspected

• Elevated alkaline phosphatase and bilirubin with a cholestatic pattern suggests choledocholithiasis or acute cholangitis 1, 2
• Leukocytosis with fever strongly suggests acute cholecystitis or cholangitis requiring urgent surgical consultation 1

If Complications or Critical Diagnoses Suspected

• Lactate level if mesenteric ischemia is suspected (a "can't miss" diagnosis) 1, 2
• Coagulation studies (PT/INR, PTT) if bleeding disorder, hepatic dysfunction, or splenic pathology is suspected 2

Critical Interpretation Pearls

Elevated white blood cell count with left shift indicates infection or inflammation such as acute cholecystitis, cholangitis, or pyelonephritis 2. The American College of Gastroenterology notes that fever with leukocytosis requires immediate referral to emergency department or acute surgical service 1.

Normal laboratory values do not exclude serious pathology—imaging studies remain necessary based on clinical presentation 2. Ultrasound has only 88% sensitivity for acute cholecystitis, so if clinical suspicion is high despite negative labs, proceed to imaging 1.

Common Pitfalls to Avoid

• Never skip the pregnancy test in women of reproductive age, as ruptured ectopic pregnancy is a life-threatening "can't miss" diagnosis 1, 2
• Do not rely solely on laboratory tests without appropriate imaging—ultrasound is rated 9/9 (usually appropriate) by the American College of Radiology as first-line imaging for RUQ pain 1, 3
• Recognize that right flank pain broadens the differential beyond pure biliary disease to include renal pathology (stones, pyelonephritis), making urinalysis essential 2
• Be aware that referred pain can occur—right upper quadrant pain with deranged liver function tests is not always hepatobiliary pathology and may represent thoracic or spinal pathology 4