Fascia iliaca compartment block (ultrasound)

Last revised by Dr David Carroll on 28 Mar 2022

The fascia iliaca compartment block is a nerve block used to provide anesthesia to the lower extremity commonly in the perioperative period. It is most commonly used for analgesia of the hip, thigh, and knee. It involves the deposition of a local anesthetic beneath the fascia iliaca, targeting the femoral, obturator, and lateral femoral cutaneous nerves 3.

  • acute analgesia for femoral neck fractures
  • perioperative analgesia for:
    • knee and hip surgery
    • above knee amputation
  • closed reduction/casting of femoral shaft fractures 1
  • lack of patient consent or cooperation
  • overlying infection
  • coagulopathy
  • nerve injury
  • hematoma/bleeding
  • local anesthetic systemic toxicity
  • peritoneal violation
  • high frequency (6-14 MHz) linear ultrasound probe
  • disinfectant agent
  • sterile ultrasound gel
  • sterile probe cover
  • local anesthetic
  • skin or block needle

Prior to the advent of ultrasound this block was performed using surface landmarks; in brief, the technique was performed by visualizing an imagined line between the anterior superior iliac spine (ASIS) and pubic tubercle, then divided into thirds 1. The point of skin puncture was located 1 centimeter inferior to the junction of the lateral and middle thirds, and (two) sequential tactile pops were noted to appreciate passage through the fascia lata (superficial) and fascia iliaca (deep).

Sonographic and anatomic landmarks (while variable based on intended technique) which should be identified during a pre-procedural scan include:

  • femoral artery
  • femoral vein
  • femoral nerve
  • iliopsoas muscle
  • fascia iliaca
  • sartorius
  • anterior superior/inferior iliac spines
  • internal oblique muscle
  • inguinal ligament

The probe is placed transversely at the midpoint of the inguinal crease, with the most conspicuous sonographic landmarks typically being the femoral artery and vein. Deep and lateral to the artery the hypoechoic iliopsoas muscle may be visualized, covered superficially in the hyperechoic fascia iliaca which envelops the femoral nerve, found just lateral to the artery, thereafter passing deep to the femoral vessels. The superficial fascia lata may also been seen 5.

Moving the probe laterally towards the sartorius allows identification of a puncture point a safe distance from the femoral neurovascular bundle. A lateral to medial approach is typically taken, and the needle tip guided in an in-plane orientation to a point just beneath the fascia iliaca 2. After negative aspiration, aliquots of local anesthetic may be deposited; proper placement of the needle tip should result in a brisk medial/lateral spread of local anesthetic, lifting the hyperechoic fascial plane from the underlying muscle. As this is a plane block, larger volumes (as tolerated by safe maximal dosing) of local anesthetic are preferable.

The ASIS is located, and the ultrasound probe should be placed just medial in a parasagittal orientation, roughly perpendicular to the inguinal ligament. Moving the probe caudad, one may identify the iliacus as it passes over the pelvic brim invested in the fascia iliaca; with slight probe adjustments one should be able to delineate the “bowtie” formed by the internal oblique cephalad, the sartorius caudad, and the height of the curved iliopsoas with the overlying fascia iliaca in the middle of one’s image 2. Care should be taken to then identify the deep circumflex iliac artery, which lies just superficial to the fascia iliaca.

In-plane needle advancement from caudal to cranial may proceed, aiming to puncture the fascia iliaca just cephalad to the pelvic brim, with injection of local anesthetic elevating the fascia iliaca, progressing to open the plane in a cranial direction, and elevating the deep circumflex iliac artery. Similar volumes of injectate are required (as compared to the infrainguinal approach).

  • femoral nerve block
  • pericapsular nerve group (PENG) block
  • popliteal sciatic nerve block

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