Fascia’s Back: The Supra-Inguinal Fascia Iliaca (SIFI) Block

Do you like Sci-Fi? You’ll love the SIFI! Since we’re in May, Star Wars fans get to celebrate with “May the 4th be with you”, but we’re here to introduce you to an even better type of SIFI: The Supra-Inguinal Fascia Iliaca (SIFI) Block. (…we’re well aware that we posted this after May 4th, but just play along).

Why?

• Hip fractures are common. At our local institution, the Ottawa Hospital, we admit approximately two patients each day. However, only about 8% of these patients receive a block in the ED.
• Delirium, pain, and opioids: Up to 50% of elderly patients with hip fractures experience delirium – poorly controlled pain, and opioids are major contributors ¹
• Long waits: Patients in Canadian ERs are waiting longer than ever before to be admitted to the hospital, underscoring the need for effective pain management.
• Blocks help: Canadian best practices and CAEP-endorsed literature recommend early fascia iliaca nerve blocks—ideally performed in the ED—as a first-line adjunct to systemic pain control.² ³

SIFI

• You’ve likely heard of, or performed, a fascia iliaca block: a high-volume plane block where local anesthetic spreads under the fascia to bathe multiple nerves.
• The original technique used landmarking and the classic “two pops” for fascia penetration, but PoCUS dramatically improved accuracy.²
• We’ve since learned that proximal blocks are more effective, capturing more branches before they diverge distally.
• Traditional (infra-inguinal) fascia iliaca blocks reliably cover the lateral femoral cutaneous nerve (LFCN) and femoral nerve but often miss the obturator nerve. A supra-inguinal (SIFI) approach improves your chances of blocking all three.⁴

Equipment

1. Nerve Block Tray

• If your shop does not have premade kits, you will need: sterile ultrasound gel, probe cover, drape, towels, chlorhexidine prep applicators, and gauze. They should also have an echogenic (Pajunk) nerve block needle.
  • Alternative: If a nerve block needle is unavailable, a 20- or 22-gauge spinal needle can suffice.

2. Local Anesthetic:

• Bupivacaine 0.25% (+ a 50-cc Syringe)
  • If < 50 kg: 30 mL
  • If ≥ 50 kg: 40 mL
• If only 0.5% bupivacaine is available: Use half the volume and dilute with sterile normal saline to maintain a total volume of at least 30–40 mL for adequate fascial spread.

3. Ultrasound Machine

• Use a high-frequency linear probe on the “Nerve” preset.
• Consent & Contraindications
  • Cover standard risks, benefits, and reasonable alternatives.
  • Standard risks: Incomplete coverage, Bleeding, Infection, Nerve Injury, LAST
  • The most serious risk is Local Anesthetic Systemic Toxicity (LAST)—know where your departmental intralipids are stored.
• Absolute contraindications – Remember: “No AIR!”
  • Neurologic deficit in the affected leg
  • Allergy to local anesthetic
  • Infection over the site
  • Refusal by the patient

Note: Anticoagulation and minimal rest pain are not contraindications. Even in patients without severe pain at rest, early blocks are recommended to facilitate movement (e.g., X-rays, CT) and reduce delirium.³

Technique

Positioning

• The patient is supine, with the ipsilateral leg slightly externally rotated (if tolerated).

Probe Placement

• Just medial to the ASIS, with the probe marker cranial.
• Slide probe inferiorly 3-4cm over inguinal ligament.

View

• Look for the “bow-tie sign”: the iliacus muscle draping over the pelvic brim.

Injection

• Insert the needle in-plane, from caudal to cranial, advancing just over the pelvic brim and beneath the fascia iliaca.
• Inject a small test aliquot—look for the characteristic “unzippering” of the fascial plane. If the local spreads within muscle, reposition.
• The injectate should spread linearly, lifting the hyperechoic fascia iliaca and the deep circumflex iliac artery (DCIA). If it surrounds vessels, the needle is too superficial.⁴
• Once proper placement is confirmed, inject the remaining local anesthetic.

Bonus PoCUS Pearls

• Having trouble seeing the fascia? Try a toe-in or tilt maneuver to reduce anisotropy — this helps sharpen fascial definition.
• Anatomy unclear? Sweep laterally from the femoral triangle to help orient your view
• Larger patients? Consider taping up the pannus or having someone assist with retraction to improve access to the inguinal region.

• 6-Minute Video Review found here