How is biliary colic diagnosed in a patient with episodic abdominal pain, possibly in the right upper quadrant, radiating to the back, and worsening after fatty meals?

Diagnosis of Biliary Colic

Biliary colic is diagnosed clinically through a combination of characteristic pain history, physical examination findings, and ultrasound imaging to confirm gallstones, though the pain pattern itself—episodic, steady epigastric or right upper quadrant discomfort lasting 1-5 hours without fluctuation—is the cornerstone of diagnosis. 1, 2

Clinical Features That Establish the Diagnosis

The pain characteristics are highly specific and must be carefully elicited:

• Location and radiation: Pain is most frequently epigastric (not right upper quadrant as commonly assumed), may radiate to the right shoulder, back, or scapula 1, 3
• Temporal pattern: Onset is abrupt, pain persists steadily without paroxysmal fluctuation, resolves gradually over 2-4 hours, and characteristically occurs at night with circadian periodicity peaking around midnight 1, 2
• Recurrence pattern: 84% of patients experience attacks at the same clock time, which is diagnostically useful 2
• Relationship to meals: Despite common teaching, biliary colic is not consistently meal-related 2
• Pain quality: Steady and relatively mild to moderate intensity, not truly "colicky" despite the name 1

Physical Examination

• Physical examination is typically normal between episodes and may show only mild right upper quadrant or epigastric tenderness during an attack 1
• Murphy's sign is not a feature of uncomplicated biliary colic (it suggests acute cholecystitis) 4
• Absence of fever, as fever suggests progression to acute cholecystitis 4

Laboratory Testing

• Laboratory tests are typically normal in uncomplicated biliary colic 5
• Elevated alkaline phosphatase or bilirubin suggests choledocholithiasis rather than simple biliary colic and warrants advanced imaging 6
• Elevated inflammatory markers (WBC, CRP) suggest acute cholecystitis rather than biliary colic 4

Imaging Strategy

Right upper quadrant ultrasound is the first-line and essential imaging study:

• Ultrasound has 96% accuracy for detecting gallstones and confirms the anatomic substrate for biliary colic 5, 7
• The radiologist must correlate imaging findings with the clinical pain pattern—the presence of gallstones alone does not establish the diagnosis without characteristic symptoms 1
• Ultrasound should be normal except for gallstones (no wall thickening, no pericholecystic fluid, no bile duct dilatation) 6, 5

When ultrasound shows gallstones but findings are equivocal:

• If pain pattern is atypical or ultrasound is negative despite high clinical suspicion, consider HIDA scan with cholecystokinin stimulation to measure gallbladder ejection fraction 8
• Biliary dyskinesia (GBEF <35%) or biliary hyperkinesia (GBEF >80%) can cause biliary colic symptoms with normal ultrasound 8
• MRCP has 85-100% sensitivity for cholelithiasis and can identify choledocholithiasis if bile duct obstruction is suspected 6

Critical Diagnostic Pitfalls to Avoid

• Do not misdiagnose epigastric pain as cardiac or peptic ulcer disease—biliary colic is frequently epigastric, not right upper quadrant 1, 3
• Do not assume CT is adequate—CT has only 75% sensitivity for gallstones and should not replace ultrasound as initial imaging 5
• Do not diagnose biliary colic based on incidental gallstones—approximately 80% of patients with gallstones are asymptomatic, so the pain pattern must match 1
• Recognize that 43-55% of patients with complicated gallstone disease (pancreatitis, cholecystitis) never experienced prior "warning" episodes of biliary colic, so absence of prior colic does not exclude gallstone-related complications 3

Differential Considerations

When evaluating suspected biliary colic, actively exclude:

• Acute cholecystitis (fever, persistent pain >6 hours, Murphy's sign, inflammatory markers) 4
• Choledocholithiasis (elevated bilirubin/alkaline phosphatase, bile duct dilatation on imaging) 6, 5
• Atypical myocardial ischemia, perforated ulcer, or other causes of epigastric pain 1
• Sphincter of Oddi dysfunction in patients with recurrent biliary-type pain after cholecystectomy or in absence of gallstones 9