What type of ultrasound should I order?

Selecting the Appropriate Ultrasound Examination

For comprehensive evaluation of suspected deep venous thrombosis (DVT), a complete duplex ultrasound protocol from thigh to ankle with Doppler at selected sites is recommended as the standard examination.1

Deep Venous Thrombosis (DVT) Ultrasound

Standard Protocol Recommendations

• Complete duplex ultrasound (CDUS) from thigh to ankle with Doppler evaluation at selected sites is the recommended standard examination for suspected DVT 1
• This comprehensive protocol is superior to limited examinations as it evaluates both proximal and calf veins, providing better diagnostic information 1
• Limited protocols that do not include calf veins are not recommended as they require a second study in 5-7 days to safely exclude DVT 1

When Point-of-Care Ultrasound is Necessary

• If complete duplex ultrasound is not available, a point-of-care ultrasound consisting of extended compression ultrasound (ECUS) from thigh to knee is appropriate 1
• After a negative ECUS, a complete duplex ultrasound in 5-7 days is required to safely exclude DVT 1
• If ultrasound is completely unavailable, anticoagulation before a confirmatory ultrasound is a safe strategy 1

Follow-Up Recommendations

• For patients with calf DVT who are managed expectantly, a repeat scan at 1 week (or sooner if symptoms worsen) is recommended 1
• For negative complete duplex ultrasound with persistent symptoms, a repeat scan in 5 days to 1 week is advised 1
• For technically compromised studies, a repeat scan in 5-7 days is recommended if more than minor limitations exist 1

Emergency Ultrasound Applications

Core Applications in Emergency Settings

• Emergency ultrasound has established core applications including trauma, intrauterine pregnancy, abdominal aortic aneurysm, cardiac, biliary, urinary tract, DVT, soft-tissue/musculoskeletal, thoracic, ocular, and procedural guidance 1
• These applications can be classified as resuscitative, diagnostic, symptom-based, procedure guidance, or therapeutic/monitoring 1

Point-of-Care Protocols

• Point-of-care ultrasound protocols should be standardized to minimize underdiagnosis of critical conditions 1
• For DVT evaluation, a single standardized point-of-care examination enhances patient safety and clinician confidence 1

Early Pregnancy Evaluation

• For stable patients in the first trimester with abdominal pain or vaginal bleeding, ultrasound is indicated 2
• Even with β-hCG levels below the discriminatory threshold (typically 1,500 mIU/mL), ultrasound may still be beneficial with approximately 33% sensitivity and 98% specificity for diagnosing intrauterine pregnancy 1, 2
• The decision to perform ultrasound should consider the patient's ability to arrange appropriate follow-up 2

Critical Care Ultrasound Applications

Pleural Effusion

• Ultrasound should be used to complement physical examination and chest radiography to diagnose and localize pleural effusions 1
• Ultrasound guidance should be used to assist in drainage of effusions, particularly small or loculated ones 1

Lung Pathology

• A systematic approach incorporating bedside ultrasound may be a primary diagnostic modality for ICU patients with respiratory failure 1
• Ultrasound has high sensitivity and specificity (>90%) for diagnosing alveolar consolidation 1

Pneumothorax Detection

• Ultrasound has sensitivity and specificity exceeding 85% for diagnosing pneumothorax, compared to 30-75% for conventional radiography 1
• Visualization of comet tail artifacts reliably excludes pneumothorax, while demonstration of a lung point without lung sliding confirms the diagnosis 1

Surveillance Ultrasound in Specific Populations

Cancer Surveillance

• For patients who have undergone partial or radical nephrectomy for kidney cancer, abdominal ultrasound is recommended within 3-12 months after surgery 1
• For patients with stage II kidney cancer, ultrasound may be used for surveillance every 3-6 months for at least 3 years 1

Genetic Syndrome Surveillance

• In patients with DICER1 syndrome, biannual to annual abdominal ultrasound is recommended starting at birth to screen for cystic nephroma or renal tumors 1
• Annual or semiannual pelvic ultrasound throughout childhood and adulthood should be considered in these patients to screen for ovarian sex cord-stromal tumors 1
• Thyroid ultrasound starting at age 8 years should be considered in DICER1 syndrome patients 1

Practical Considerations

• Ultrasound is widely available, extremely safe, portable, and inexpensive compared to other imaging modalities 3
• Modern ultrasound has progressed beyond anatomical imaging to include tissue perfusion studies, molecular imaging, and therapeutic applications 3
• For vascular access procedures, providers should use real-time, two-dimensional ultrasound guidance with a high-frequency linear transducer 4

Common Pitfalls to Avoid

• Avoid using static ultrasound alone to mark needle insertion sites for vascular access procedures 4
• Avoid limited DVT protocols that exclude calf veins, as they require follow-up studies and may miss isolated femoral vein DVTs 1
• Be cautious with terminology - use "chronic postthrombotic change" to describe residual material that persists after acute DVT to avoid potential overtreatment of prior thrombus 1