A 28-year-old woman undergoes femoral artery catheterization for coronary angiography via the right groin. Six hours post-procedure, she develops a pulsatile swelling in the femoral triangle with pain and a systolic bruit on auscultation. Distal pulses are intact. What is the most appropriate next step in management?

Explanation

## Post-Catheterization Femoral Artery Pseudoaneurysm ### Clinical Scenario A pulsatile mass in the femoral triangle with a systolic bruit following femoral artery puncture is pathognomonic for a **pseudoaneurysm** (false aneurysm). This is a known complication of femoral artery catheterization. ### Correct Approach: Duplex Ultrasonography **Key Point:** Duplex ultrasound is the gold standard first-line imaging modality for diagnosis and assessment of femoral artery pseudoaneurysm. It is non-invasive, real-time, and guides management decisions. **High-Yield:** Pseudoaneurysm occurs when the arterial puncture site fails to seal, creating a communication between the artery and surrounding tissue. The "to-and-fro" flow pattern on duplex is diagnostic. **Mnemonic for Pseudoaneurysm Features:** **PULSATILE** — Pulsatile mass, Ultrasound shows to-and-fro flow, Location at puncture site, Systolic bruit, Arterial communication, Tender, Intact distal pulses, Leak from artery, Expansion risk. ### Duplex Ultrasound Findings - **To-and-fro flow** (pathognomonic): systolic flow into the sac, diastolic flow back into the artery - Measures pseudoaneurysm size, neck diameter, and relationship to surrounding structures - Assesses femoral artery patency and distal flow ### Management Algorithm Based on Duplex Findings ```mermaid flowchart TD A[Pseudoaneurysm on duplex]:::outcome --> B{Size and symptoms?}:::decision B -->|Small <2 cm, asymptomatic| C[Observation + serial ultrasound]:::action B -->|Large >2 cm OR symptomatic| D{Neck diameter?}:::decision D -->|Narrow neck <6 mm| E[Ultrasound-guided compression repair]:::action D -->|Wide neck| F[Thrombin injection or surgical repair]:::action C --> G[Repeat duplex at 2-4 weeks]:::action E --> H[Success in 80-90% of cases]:::outcome F --> I[Definitive repair]:::outcome ``` **Clinical Pearl:** Intact distal pulses suggest the pseudoaneurysm is not causing hemodynamic compromise, making conservative management or minimally invasive repair (ultrasound-guided compression or thrombin injection) appropriate. [cite:Gray's Anatomy Ch 41; Harrison 21e Ch 256]