What is the initial approach for an 18-year-old female with upper abdominal pain and normal vitals?

Initial Approach to Upper Abdominal Pain in an 18-Year-Old Female with Normal Vitals

Obtain a urine pregnancy test immediately, then perform ultrasonography of the abdomen as your first-line imaging study, preceded by basic laboratory tests including CBC, liver function tests, lipase, and urinalysis. 1, 2, 3

Immediate First Steps

Mandatory Pregnancy Testing

• A pregnancy test (β-hCG) must be performed before any imaging studies in all females of reproductive age to prevent unnecessary radiation exposure and identify pregnancy-related emergencies like ectopic pregnancy. 1, 2, 3
• This is non-negotiable and takes priority over imaging decisions. 1, 2

Initial Laboratory Workup

• Complete blood count (CBC) to assess for leukocytosis indicating infection or inflammation 1, 3
• Liver function tests (ALT, AST, alkaline phosphatase, bilirubin) to evaluate hepatobiliary disease 1, 2, 3
• Serum lipase (more specific than amylase) to rule out pancreatitis 3, 4
• Urinalysis to evaluate for urinary tract infection or nephrolithiasis 2, 3
• Comprehensive metabolic panel to assess organ function and electrolytes 3

First-Line Imaging: Ultrasonography

Ultrasonography of the abdomen is the initial imaging study of choice for upper abdominal pain in teenage females, with the highest appropriateness rating (9/9) from the American College of Radiology. 1, 2

Why Ultrasound First

• No radiation exposure—critical in younger patients 1, 2
• Excellent for evaluating gallbladder pathology (cholecystitis, cholelithiasis) 5, 1, 2
• Effective for liver abnormalities, pancreatic conditions, and hepatobiliary tract disease 1, 2
• Readily available and can be performed quickly 2
• Superior to CT as initial imaging for right upper quadrant pain 2

Specific Ultrasound Targets

• Right upper quadrant pain: gallbladder pathology, liver abnormalities, hepatobiliary disease 1, 2
• Left upper quadrant pain: splenic pathology, pancreatic conditions, left kidney abnormalities 1

Second-Line Imaging (If Ultrasound Non-Diagnostic)

When Symptoms Persist Despite Negative Ultrasound

• MRI with MRCP is superior to CT for biliary sources of pain, with 85-100% sensitivity for cholelithiasis/choledocholithiasis 2
• MRI provides excellent visualization of the cystic duct and common bile duct without radiation 5, 2
• CT abdomen/pelvis with IV contrast may be considered as second-line if ultrasound is non-diagnostic and MRI unavailable 1, 2

Critical Pitfalls to Avoid

• Never skip pregnancy testing before imaging—this prevents unnecessary radiation and identifies ectopic pregnancy 1, 2, 3
• Do not use CT as first-line imaging in younger patients due to radiation concerns when ultrasound is highly effective 1, 2
• Do not order conventional radiography (plain X-rays)—they have minimal diagnostic value for upper abdominal pain 1, 2, 3
• Do not rely solely on laboratory tests without appropriate imaging when indicated, as this leads to delayed diagnosis 1

Differential Diagnosis to Consider

Based on history and examination findings, consider:

• Biliary pathology: cholecystitis, cholelithiasis (most common in young females) 5, 2, 4
• Gastroenteritis: most common cause of acute abdominal pain overall 4
• Pancreatitis: evaluate with lipase 3, 4
• Peptic ulcer disease or gastritis 4
• Pregnancy-related conditions: ectopic pregnancy, early pregnancy complications 1, 2, 3
• Urolithiasis: right or left sided 3, 4
• Hepatitis or liver pathology 1, 2

Key History Elements to Elicit

• Last menstrual period and sexual activity (pregnancy risk) 1, 2, 3
• Timing and character of pain (constant vs. intermittent, colicky vs. steady) 6, 4
• Associated symptoms: nausea, vomiting, fever, changes in bowel habits 5, 4
• Food intake and relationship to meals (biliary colic worsens after fatty meals) 5
• Previous similar episodes or abdominal surgeries 5, 4