Sonographic Anatomy and performing the block

Method 1. Femoral artery identification and lateral scanning

Step 1. With probe marker pointing towards ASIS (from the femoral artery and vein are identified. The nerve lies lateral to the artery. Probe depth should be set to 3cm, and a linear 5-11Hz probe selected.

Step 2. The probe is moved lateral towards the ASIS, the iliacus muscle is identified with the fasia iliaca and fascia late superior.

Step 3. The needle is inserted and visualised in plane. A pop may be felt as it passes through the fascia lata and fascia iliaca. The needle should be placed under the fascia iliaca and the fascia hydro-dissected from the ilacus muscle.

The syringe should be aspirated prior to infiltration, and then a test dose of 1-2mls injected to confirm position. The probe can scan medially to confirm spread towards the femoral nerve.

(Local anaesthetic spread shown in blue.)

This flow chart can help guide you through the block process.

For further information on this block click here.

An excellent video demonstrating the sonographic technique is available here.