What is the proper procedure for ordering an abdominal ultrasound?

How to Order an Abdominal Ultrasound

Abdominal ultrasound should be ordered as the initial imaging modality for most patients presenting with abdominal symptoms, particularly for right upper quadrant pain, suspected biliary disease, or when evaluating hepatocellular abnormalities. 1, 2

Clinical Indications for Ordering Abdominal Ultrasound

Primary Indications (Ultrasound as First-Line)

Right Upper Quadrant Pain:

• Order ultrasound immediately for suspected cholecystitis or cholelithiasis 1, 2
• Sensitivity of 81% and specificity of 83% for cholecystitis 2
• Can detect gallstones, gallbladder wall thickening >3mm, pericholecystic fluid, and sonographic Murphy's sign 1

Abnormal Liver Function Tests:

• For hepatocellular predominance with mild aminotransferase elevation, order US abdomen with Doppler 1
• For cholestatic pattern with elevated alkaline phosphatase, ultrasound is appropriate as initial imaging 1
• For jaundice evaluation, ultrasound at admission to assess for cholelithiasis or choledocholithiasis 1

Acute Pancreatitis:

• Order abdominal ultrasound at admission to evaluate for gallstone etiology 1
• If initial ultrasound is inadequate, repeat after recovery 1

Blunt Abdominal Trauma (Hemodynamically Unstable):

• Bedside FAST (Focused Assessment with Sonography for Trauma) examination can be performed rapidly during resuscitation 1
• Sensitivity of 83-100% for detecting free intraperitoneal fluid requiring intervention 1

Secondary Indications (Consider Ultrasound)

Left Lower Quadrant Pain:

• Ultrasound may reduce unnecessary CT examinations in suspected diverticulitis, though CT with contrast remains preferred in the United States 1

Liver Lesion Characterization:

• For incidental liver lesions <1 cm on other imaging, ultrasound can prove cystic nature in 67% of cases 1
• Contrast-enhanced ultrasound (CEUS) correctly characterizes 95% of subcentimeter lesions 1

Ordering Specifications

Essential Order Components

Patient Preparation:

• NPO (nothing by mouth) for 6-8 hours prior to examination for optimal gallbladder and upper abdominal visualization 3
• Full bladder required if pelvic structures need evaluation as part of complete abdominal study 4

Order Details to Include:

• Specify "complete abdominal ultrasound" or target specific region (e.g., "right upper quadrant ultrasound") 1, 3
• Include clinical indication and specific question to be answered 1
• Note any relevant laboratory values (liver enzymes, bilirubin, lipase) 1
• Document pertinent physical findings (location of tenderness, Murphy's sign, masses) 1, 2

Special Considerations:

• Add Doppler evaluation when assessing for vascular pathology, portal hypertension, or hepatic abnormalities 1
• Consider contrast-enhanced ultrasound (CEUS) for liver lesion characterization if available 1
• For trauma patients, specify "FAST examination" for focused assessment 1

When NOT to Order Ultrasound First

Order CT with Contrast Instead:

• Right or left lower quadrant pain (CT preferred over ultrasound in United States) 1, 2
• Suspected appendicitis (CT sensitivity >95%) 2
• Suspected diverticulitis with complications 1
• Diffuse or nonlocalized abdominal pain 2
• Hemodynamically stable trauma patients requiring comprehensive evaluation 1

Order MRI with MRCP Instead:

• Suspected biliary obstruction requiring detailed ductal evaluation 1
• Indeterminate liver lesions >1 cm requiring characterization 1

Common Pitfalls to Avoid

Technical Limitations:

• Ultrasound has limited sensitivity for bowel pathology, retroperitoneal structures, and in obese patients 5
• Cannot reliably exclude small bowel obstruction or detect extraluminal air 1
• Operator-dependent with significant inter-observer variability 5

Clinical Errors:

• Do not delay CT imaging in hemodynamically stable patients with acute abdomen when ultrasound is non-diagnostic 2
• Avoid ordering "routine" whole abdominal ultrasound without specific lower abdominal indications—74.8% show no significant findings and delay care 4
• Do not rely on ultrasound alone for suspected acute cholecystitis with high clinical suspicion but negative initial study—consider repeat imaging or alternative modality 1
• Pregnancy test is mandatory before ordering any abdominal imaging in women of reproductive age 2

Documentation Requirements:

• Results should be incorporated into medical record with indication, views obtained, organs studied, and interpretation 1
• Images should be archived per facility policy 1