Ruling Out Digital Vascular Injury
CT angiography (CTA) is the first-line imaging modality to rule out digital vascular injury, with 96.2% sensitivity and 99.2% specificity for detecting vascular injuries in limb trauma. 1
Clinical Assessment First
Before imaging, perform a focused vascular examination looking for:
- Hard signs of vascular injury requiring immediate surgical exploration without imaging: active arterial bleeding, expanding hematoma, absent distal pulses, or signs of acute ischemia (pale, cold digit) 1, 2
- Soft signs that allow time for imaging: non-expanding hematoma, proximity of injury to digital vessels, isolated sensory deficit, or diminished but present pulses 1, 2
Ankle-Brachial Index Equivalent for Digits
Measure digital-brachial pressure index using Doppler ultrasound if available. 1
- Apply a small cuff just proximal to the injury site
- Use a Doppler probe at 45° angle to detect arterial flow distally
- Calculate the ratio of digital systolic pressure to brachial systolic pressure
- An index <0.9 has 87% sensitivity and 97% specificity for vascular injury 1
- If the index is normal AND there are no clinical signs of vascular injury, the probability of arterial injury is virtually zero (negative likelihood ratio 0.01) 1
Imaging Algorithm
When to Proceed with CTA
Obtain CTA if any of the following are present: 1, 3
- Externalized bleeding of arterial origin
- Injury site in proximity to main digital vascular axis
- Presence of non-expanding hematoma
- Isolated neurological deficit (sensory loss in digital nerve distribution)
- Digital-brachial index <0.9
- Large hematoma with concern for vascular compromise
CTA Technical Considerations
- CTA has replaced catheter angiography as first-line imaging with sensitivity 90-100% and specificity 98.6-100% for vascular injuries 1
- Imaging should extend from the hand through the entire digit to visualize the complete digital arterial anatomy 1
- CTA provides simultaneous evaluation of soft tissue and bony injuries 1
When CTA is Limited
Consider catheter angiography (digital subtraction angiography) if: 1
- CTA shows equivocal findings
- Metallic foreign bodies create streak artifact limiting CTA interpretation
- Endovascular therapy is being considered
- CTA is technically inadequate
Common Pitfalls to Avoid
- Do not delay imaging if vascular compromise is suspected - acute digital ischemia requires urgent recognition and treatment to prevent necrosis and preserve function 4, 5
- Single digital artery injuries may not require repair due to collateral flow from the contralateral digital artery, but this must be confirmed by demonstrating adequate perfusion 6
- Closed injuries can cause digital artery injury - do not assume vascular integrity based on intact skin alone, especially with crush mechanisms or fractures near interphalangeal joints 4
- Complete vascular assessment includes both arteries and veins - venous outflow obstruction can also cause digital ischemia 7
Surgical Exploration Indications
Proceed directly to surgical exploration without imaging if: 2, 6
- Active hemorrhage with hemodynamic instability
- Complete digit amputation
- Obvious complete circumferential vascular injury
- Progressive ischemia despite adequate assessment
Plan for surgical exploration after imaging if: 6, 5
- CTA or angiography confirms arterial injury
- Dysvascular digit with threatened viability
- Complete arterial transection requiring repair for border digits (thumb, radial index finger, ulnar small finger)
The goal is digit preservation and restoration of function through early recognition and aggressive treatment when indicated 5.