How to assess digital vascularity in a patient with a laceration on the mid-digit, considering potential pre-existing vascular conditions or medications that may affect blood flow?

Assessment of Digital Vascularity in Mid-Digit Laceration

In a mid-digit laceration, assess digital vascularity immediately using capillary refill, digital color/temperature comparison to the contralateral digit, and handheld Doppler ultrasound to detect arterial flow in both digital arteries—these bedside methods are sufficient to determine if vascular repair is needed, as formal imaging is rarely indicated for isolated digital injuries. 1

Immediate Bedside Assessment

Clinical Examination Components

• Check capillary refill in the injured digit distal to the laceration, comparing to the contralateral digit; normal refill is <2 seconds and indicates adequate perfusion 1
• Assess digital color and temperature by comparing the injured digit to the uninjured contralateral digit; pallor, cyanosis, or coolness suggests arterial insufficiency 1
• Palpate for digital pulses if the digit is large enough, though this is often unreliable in fingers due to vessel size 1
• Test for active bleeding from the wound; pulsatile bright red bleeding suggests arterial injury, while oozing dark blood suggests venous injury 2

Handheld Doppler Assessment

• Use an 8-10 MHz handheld Doppler probe to interrogate both radial and ulnar digital arteries along the lateral aspects of the digit 3, 4
• Document presence or absence of arterial signals in each digital artery; absence of signal in one artery with normal capillary refill indicates adequate collateral flow through the remaining artery 2
• Perform a modified Allen test by occluding one digital artery while checking Doppler signal in the other to assess collateral circulation 2

Decision Algorithm for Vascular Intervention

When Vascular Repair is NOT Required

• If capillary refill is normal (<2 seconds) and at least one digital artery has Doppler signal, simple ligation of the injured artery is safe and cost-effective, as hand symptoms relate to nerve or tendon damage rather than arterial patency 2
• Single digital artery laceration with intact contralateral artery does not require repair, as patency following digital artery repair does not exceed 50% and provides no clinical benefit over ligation 2

When Vascular Repair IS Required

• If capillary refill is >3 seconds, the digit is pale/cool, and no Doppler signals are detected in either digital artery, this indicates acute digital ischemia requiring immediate arterial repair 1
• If both digital arteries are transected with signs of ischemia, at least one artery must be repaired to restore perfusion 2

Role of Advanced Imaging

When Imaging is NOT Needed

• Isolated digital lacerations do not require CT angiography, duplex ultrasound, or formal angiography if bedside assessment demonstrates adequate perfusion 1, 3
• The cost of formal vascular imaging and repair is 3-4 fold higher than simple ligation without demonstrable clinical benefit in single-vessel digital injuries 2

When Imaging May Be Considered

• If there is concern for proximal vascular injury (at the wrist or forearm level) with diminished radial or ulnar pulses, obtain ankle-brachial index equivalent for the upper extremity or duplex ultrasound 1, 3
• CT angiography has 96.2% sensitivity and 99.2% specificity for detecting vascular injuries in limb trauma but is reserved for complex injuries with suspected proximal involvement 1

Critical Pitfalls to Avoid

• Do not assume both digital arteries must be patent for adequate hand function; collateral circulation through one artery is sufficient in most cases 2
• Do not routinely repair single digital artery lacerations based solely on the presence of injury, as repair patency rates are poor (46%) and do not improve outcomes compared to ligation 2
• Do not delay assessment; evaluate digital perfusion immediately upon presentation, as symptoms developing over hours suggest progressive ischemia requiring intervention 1
• Do not attribute later hand symptoms to arterial patency; weakness, cold sensitivity, and paresthesias relate to associated nerve injury, not vascular status 2

Special Considerations for Pre-existing Conditions

Patients on Anticoagulation or Antiplatelet Therapy

• Assess for ongoing bleeding from the wound, as these medications may prolong hemorrhage but do not change the vascular assessment algorithm 1
• Document medication history including aspirin, clopidogrel, warfarin, or direct oral anticoagulants, as this may influence surgical decision-making for repair 1

Patients with Peripheral Vascular Disease

• Compare digital perfusion to the contralateral hand to distinguish acute traumatic injury from chronic baseline ischemia 1
• Consider that patients with known PAD can develop acute-on-chronic thrombosis after trauma, requiring more aggressive intervention 1
• Use Doppler assessment bilaterally to establish baseline vascular status before attributing findings solely to the laceration 3, 4