A 58-year-old man from Delhi presents to the emergency department with acute right groin pain and swelling following a fall while climbing stairs. On examination, there is a tender, pulsatile mass in the right groin below the inguinal ligament. The mass is expansile on palpation, and a continuous 'machinery' murmur is heard on auscultation. Femoral pulses are bounding distally. What is the most likely vascular complication at this anatomical site?

Explanation

## Clinical Diagnosis: Femoral Artery Pseudoaneurysm with Arteriovenous Fistula ### Anatomical Context The femoral triangle is bounded by: - **Medial:** Medial border of adductor longus - **Lateral:** Medial border of sartorius - **Superior:** Inguinal ligament - **Floor:** Pectineus, adductor longus, iliopsoas The femoral artery and vein lie within this triangle, making them vulnerable to blunt or penetrating trauma. ### Key Clinical Features Supporting the Diagnosis **Key Point:** The triad of pulsatile mass + continuous machinery murmur + bounding distal pulses is pathognomonic for arteriovenous fistula (AVF). | Feature | Mechanism | Clinical Significance | |---------|-----------|----------------------| | Pulsatile, expansile mass | Pseudoaneurysm (contained rupture) | Indicates active bleeding into tissues | | Machinery murmur | Turbulent flow from artery → vein | Pathognomonic for AVF | | Bounding pulses distally | Decreased peripheral resistance from shunt | Increased cardiac output to compensate | | Warm overlying skin | Increased blood flow through fistula | Hyperthermia at site | ### Pathophysiology 1. **Trauma mechanism:** Fall with blunt force to groin → intimal tear in femoral artery 2. **Pseudoaneurysm formation:** Blood escapes arterial lumen but contained by surrounding fascia 3. **AVF development:** Continued bleeding erodes into adjacent femoral vein, creating direct arteriovenous communication 4. **Hemodynamic consequence:** Shunt flow bypasses capillary bed → decreased peripheral resistance, increased cardiac output, bounding pulses **High-Yield:** The machinery murmur results from continuous high-velocity flow from high-pressure artery directly into low-pressure vein, creating turbulence throughout the cardiac cycle. ### Why This Location Matters **Clinical Pearl:** The femoral triangle is a common site for iatrogenic vascular injury (femoral artery puncture for angiography, cardiac catheterization) and trauma. The superficial location makes it amenable to ultrasound diagnosis and intervention. ### Diagnostic Confirmation - **Duplex ultrasound:** First-line imaging — shows pseudoaneurysm sac, bidirectional flow in fistula tract - **CT angiography:** If extent of injury or distal involvement unclear - **Angiography:** Reserved for intervention (endovascular repair) ### Management - **Immediate:** Compression (if stable), IV access, cross-matched blood - **Definitive:** Percutaneous thrombin injection (preferred) or surgical repair **Mnemonic: FEMORAL AVF = Fistula, Expansile mass, Machinery murmur, Overflow (bounding pulses), Rupture (pseudoaneurysm), Artery-Vein, Loss of resistance**