Fascia iliaca block

12 min read Last updated April 9, 2026

Surgical approach (where relevant)

  • Not a surgical operation, used to facilitate/optimise care around hip/femur surgery and ED management
  • Typical perioperative contexts
    • Neck of femur fracture: pre-op analgesia, positioning for spinal, opioid-sparing, delirium reduction strategy
    • Femoral shaft fracture, femoral neck/acetabulum injuries (variable coverage)
    • Post-op analgesia after hip arthroplasty/hip fracture fixation (as part of multimodal plan)

Anaesthetic management (typical scenarios)

  • Type of anaesthesia
    • Analgesic regional block, performed awake/sedated, commonly adjunct to spinal for NOF fracture surgery
    • Can be used with GA or neuraxial, does not replace anaesthesia for surgery
  • Airway (if in theatre)
    • If GA: ETT or SGA depending on surgery/aspiration risk, NOF patients often higher aspiration risk and frail—individualise
  • Duration
    • Block performance: ~5–10 min (ultrasound), onset typically 10–30 min depending on LA and volume
    • Analgesia duration: ~6–18 h (agent dependent, longer with adjuncts/catheters)
  • How painful is the underlying condition/surgery?
    • Hip fracture and femoral fractures: severe pain, movement/positioning very painful, high opioid sensitivity in elderly
    • Hip arthroplasty/fixation: moderate–severe post-op pain, multimodal analgesia required

Indications and aims

  • Analgesia for hip fracture, femoral fractures, anterior thigh pain, facilitates positioning for spinal/transfer/imaging
  • Opioid-sparing in frail elderly (reduce nausea, respiratory depression, delirium risk, improve mobilisation/physio participation)
  • Can be delivered as single-shot or catheter (continuous infusion/intermittent bolus) for ongoing analgesia

Relevant anatomy (exam core)

  • Target plane: beneath fascia iliaca, superficial to iliopsoas muscle (iliacus) in the iliac fossa
  • Nerves potentially affected
    • Femoral nerve (L2–L4): anterior thigh sensation, quadriceps motor, contributes to hip pain
    • Lateral femoral cutaneous nerve (L2–L3): lateral thigh sensation
    • Obturator nerve (L2–L4): medial thigh sensation, adductor motor, often inconsistently blocked with classic infra-inguinal FIB
      • More reliable obturator coverage with proximal/“supra-inguinal” approach (spread towards lumbar plexus)
  • Key landmarks/structures on ultrasound (infra-inguinal approach)
    • Femoral artery (medial), femoral nerve (lateral to artery, under fascia iliaca), iliopsoas muscle deep
    • Fascia lata (superficial) and fascia iliaca (deeper) are two distinct hyperechoic lines
  • Dermatomal/clinical effect (typical)
    • Reduced pain from hip fracture/anterior thigh, variable lateral thigh numbness, quadriceps weakness possible

Techniques (what you should be able to describe in a viva)

  • Approaches
    • Infra-inguinal (classic): injection below fascia iliaca lateral to femoral nerve/artery at inguinal crease
    • Supra-inguinal: injection cephalad to inguinal ligament to encourage proximal spread (better LFCN/obturator coverage)
    • Landmark (loss-of-resistance “two pops”): less reliable and higher risk of failure/complications vs ultrasound
  • Ultrasound-guided infra-inguinal: stepwise
    • Position: supine, slight external rotation, expose inguinal region, consider analgesia/sedation cautiously
    • Probe: high-frequency linear, transverse at inguinal crease, identify femoral artery then femoral nerve lateral
    • Identify fascia lata and fascia iliaca, aim needle tip under fascia iliaca (not just under fascia lata)
    • Needle: in-plane lateral-to-medial commonly, aspirate, hydrodissect with small aliquots to confirm correct plane
    • Inject large volume to promote spread laterally/cephalad, observe separation of fascia iliaca from iliopsoas and spread around femoral nerve
  • Supra-inguinal: stepwise (high-yield differences)
    • Probe placed just medial to ASIS, oriented to visualise iliacus muscle and fascia iliaca, needle advanced to plane deep to fascia iliaca
    • Aim for cranial spread towards iliac fossa/lumbar plexus to improve LFCN and obturator involvement

Local anaesthetic choice, dose and practical prescribing (UK exam style)

  • Principle: FIB is a fascial plane block → success depends on volume and correct plane more than precise nerve contact
  • Typical single-shot volumes (adult)
    • Infra-inguinal: 30–40 mL commonly used (adjust to patient size, frailty, and maximum safe dose)
    • Supra-inguinal: often 30–40 mL, may achieve better proximal spread at similar volumes
  • Common LA regimens (examples, always calculate maximum safe dose and consider frailty)
    • Ropivacaine 0.2–0.375% 30–40 mL (good sensory with less motor than bupivacaine at equipotent doses)
    • Levobupivacaine 0.25% 30–40 mL (longer duration, more motor block possible)
    • Lidocaine 1% (with/without adrenaline) for faster onset if needed, shorter duration
  • Adjuvants
    • Dexamethasone (perineural/off-label) may prolong duration, consider local policy and consent
    • Avoid mixing multiple LAs without clear rationale, increases dosing complexity and toxicity risk
  • Catheter technique (if used)
    • Thread catheter 3–5 cm in plane under fascia iliaca, secure well, label, document sensory/motor baseline
    • Infusion examples: ropivacaine 0.2% at 5–10 mL/h or intermittent bolus per local protocol, monitor quadriceps strength and falls risk

Contraindications and precautions

  • Absolute
    • Patient refusal, allergy to LA, infection at injection site
  • Relative / caution
    • Anticoagulation: FIB is a superficial fascial plane block (generally lower bleeding risk than deep plexus blocks) but still consider compressibility, local policy, and patient-specific risk
    • Sepsis/systemic infection (risk–benefit), altered anatomy, previous groin surgery
    • Severe hypovolaemia/shock: prioritise resuscitation, avoid masking evolving compartment/ischemic pain (rare context)
    • Pre-existing femoral neuropathy: document baseline deficits, counsel re attribution

Complications and how to reduce them

  • Local anaesthetic systemic toxicity (LAST)
    • Risk increased by large volumes, frailty, low body weight, hepatic dysfunction, inadvertent intravascular injection
    • Mitigation: dose calculation, incremental injection with aspiration, ultrasound visualisation, consider adrenaline marker dose if appropriate, monitoring
    • Management: stop injection, call for help, airway/oxygen/ventilation, treat seizures, lipid emulsion, manage arrhythmias per guidelines
  • Vascular puncture/haematoma
    • Avoid medial needle trajectory, identify femoral vessels, use colour Doppler if uncertain, compress if puncture
  • Nerve injury
    • Less likely than femoral nerve block (needle not aimed at nerve), but still possible, avoid intraneural injection, stop if pain/paraesthesia/high pressure
  • Block failure / incomplete analgesia
    • Common causes: injection above fascia iliaca (only under fascia lata), inadequate volume, poor spread, wrong approach for pain source (posterior hip pain)
    • Management: reassess anatomy, consider repeat under ultrasound within safe dosing, add systemic analgesia, consider alternative blocks (PENG, femoral, LPB) depending on indication and expertise
  • Motor weakness and falls risk
    • Quadriceps weakness can occur, ensure mobilisation plan accounts for this, document and communicate to ward/physio, consider lower concentration/ropivacaine
  • Infection (especially catheters)
    • Asepsis, sterile probe cover/gel, secure dressing, daily review and timely removal
  • FIB vs femoral nerve block
    • FIB: fascial plane, larger volume, potentially covers femoral + LFCN (± obturator), less needle-near-nerve, good for hip fracture pathways
    • Femoral nerve block: targeted femoral nerve, reliable anterior thigh analgesia, more direct motor block, may miss LFCN/obturator
  • FIB vs PENG block (pericapsular nerve group)
    • PENG aims at articular branches to anterior hip capsule (femoral, obturator, accessory obturator) and may be more motor-sparing, technique-dependent and evolving evidence base
    • FIB is simpler, widely taught, may provide broader cutaneous coverage but can cause quadriceps weakness
  • FIB vs lumbar plexus block
    • Lumbar plexus block is deep, higher bleeding/neuraxial spread risk, requires expertise, stronger analgesia/coverage but greater complication profile

Documentation and governance (often tested indirectly)

  • Record: indication, consent, side, technique (US/landmark), needle approach, LA drug/concentration/volume, total dose (mg), aspiration, complications, sensory/motor assessment, post-block instructions
  • Communicate falls risk and mobilisation advice, ensure ward knows block performed and expected duration

Test yourself…

Describe how you would perform an ultrasound-guided infra-inguinal fascia iliaca block for a patient with a fractured neck of femur.

Aim: deposit LA deep to fascia iliaca to allow spread to femoral nerve and LFCN (± obturator).

  • Preparation: confirm indication, consent/capacity, allergies, anticoagulation status, baseline neuro exam, monitoring (ECG/NIBP/SpO2), IV access, resus drugs and lipid available
  • Position: supine, expose groin, analgesia/sedation cautiously (frail elderly, avoid oversedation)
  • Asepsis: sterile gloves, skin prep, sterile probe cover and gel
  • Scan: linear probe transverse at inguinal crease, identify femoral artery then femoral nerve lateral, identify fascia lata and fascia iliaca
  • Needle: in-plane lateral-to-medial, advance to just deep to fascia iliaca, confirm with hydrodissection
  • Inject: incremental aliquots with aspiration, aim for spread under fascia iliaca laterally/cephalad, total volume typically 30–40 mL within safe dose
  • Aftercare: monitor for LAST, document, reassess pain and quadriceps strength, communicate falls risk and expected duration
Which nerves does a fascia iliaca block cover, and why can it be unreliable for obturator nerve blockade?

Coverage depends on LA spread within the fascia iliaca compartment.

  • Most consistent: femoral nerve, often: lateral femoral cutaneous nerve
  • Obturator nerve: inconsistent with infra-inguinal approach because obturator lies more medial/deeper and outside the main spread pathway, requires more proximal spread (supra-inguinal) to improve likelihood
  • Clinical implication: hip fracture pain may persist (especially medial thigh/adductor-related or posterior capsule pain) despite a technically correct infra-inguinal FIB
Explain the ultrasound anatomy you expect to see for an infra-inguinal fascia iliaca block.

Key is distinguishing fascia lata from fascia iliaca and locating femoral vessels/nerve.

  • Femoral artery (pulsatile, anechoic lumen) with femoral vein medial, femoral nerve hyperechoic/oval lateral to artery
  • Two fascial layers: fascia lata superficial, fascia iliaca deeper over iliopsoas/iliacus
  • Target plane: deep to fascia iliaca, correct injection separates fascia iliaca from iliopsoas with visible LA spread
What local anaesthetic and volume would you choose for a fascia iliaca block in a 50 kg frail elderly patient? Talk through your safety considerations.

FRCA focus: safe dosing, frailty, large-volume plane block, LAST mitigation.

  • Choose a long-acting LA at lower concentration to allow volume while staying within maximum dose (e.g., ropivacaine 0.2–0.25% or levobupivacaine 0.125–0.25%)
  • Calculate maximum safe dose (mg/kg) and reduce further for frailty/low muscle mass, consider using 25–30 mL rather than 40 mL if dose-limited
  • Inject incrementally with aspiration, use ultrasound to avoid intravascular injection, monitor closely and have lipid immediately available
  • Balance analgesia vs motor block/falls risk, communicate to ward and physio
A patient becomes agitated and then has a seizure shortly after you inject local anaesthetic for a fascia iliaca block. What is your diagnosis and immediate management?

This is presumed LAST until proven otherwise.

  • Stop injection, call for help, ABC approach with 100% oxygen, support ventilation to avoid hypercarbia/acidosis
  • Treat seizures: benzodiazepine first line, avoid large propofol doses in cardiovascular instability
  • Start lipid emulsion therapy per guideline, continue resuscitation and manage arrhythmias (avoid lidocaine, cautious with adrenaline dosing)
  • Post-event: ICU/HDU monitoring, document and report, review dosing and technique
How does a supra-inguinal fascia iliaca block differ from an infra-inguinal approach, and what are the potential advantages?

Difference is injection site relative to inguinal ligament and intended proximal spread.

  • Supra-inguinal is performed cephalad to inguinal ligament near ASIS with the aim of cranial spread in iliac fossa
  • Potential advantages: improved LFCN block and higher chance of obturator involvement, may provide better hip analgesia
  • Same safety principles: large volume, dose limitation, LAST vigilance
Your fascia iliaca block has not worked. Give a structured approach to troubleshooting.

Think: wrong patient/problem, wrong plane, wrong dose/volume, wrong time, or alternative pain source.

  • Reassess pain source: posterior hip pain or non-femoral distribution may not respond, consider PENG or alternative strategies
  • Check timing: allow adequate onset (10–30 min depending on LA)
  • Review technique: was LA injected under fascia iliaca (not just under fascia lata)? Was spread seen? Adequate volume?
  • If safe: repeat under ultrasound within maximum dose, otherwise add systemic analgesia and non-opioid adjuncts
  • Document and communicate, consider senior help for alternative blocks
Discuss the risks and benefits of fascia iliaca block in an anticoagulated patient with a hip fracture.

FRCA expects risk stratification and pragmatic governance.

  • Benefit: strong opioid-sparing analgesia facilitating care and neuraxial positioning, may reduce delirium/respiratory complications
  • Bleeding risk: generally lower than deep plexus blocks because it is superficial and compressible, but vascular puncture/haematoma still possible
  • Approach: check drug/timing/renal function, follow local/regional anaesthesia anticoagulation guidance, use ultrasound to avoid vessels, apply compression if needed
  • Communicate and document shared decision-making, monitor for expanding haematoma or neurovascular compromise
What are the key points you would include when consenting a patient for a fascia iliaca block?

Consent should be proportionate, patient-specific, and documented.

  • Benefits: improved pain control, less opioid, easier movement/positioning, possibly reduced nausea/delirium
  • Common/important risks: failure/incomplete block, bruising/bleeding, infection, temporary leg weakness/numbness and falls risk
  • Serious but rare: LAST (seizure/cardiac arrest), nerve injury
  • Alternatives: systemic analgesia, other regional blocks, no block
How would you assess and document block success after a fascia iliaca block?

Assess pain and function, not just sensation.

  • Pain scores at rest and on movement (e.g., passive leg raise/roll), opioid requirements, ability to tolerate positioning
  • Sensory testing: anterior thigh (femoral), lateral thigh (LFCN), medial thigh (obturator—often unreliable)
  • Motor: quadriceps strength (knee extension/straight leg raise) and mobilisation advice/falls precautions
  • Document timing, findings, and any adverse events
You are asked to provide analgesia for an 86-year-old with a fractured neck of femur in ED. Discuss the role of fascia iliaca block and how you would deliver it safely.

Structure: indication/benefits → assessment/consent → technique → dosing → monitoring/complications → governance.

  • Role: early analgesia, opioid-sparing, facilitate movement/positioning for spinal, potentially reduce delirium/respiratory depression
  • Assessment: pain severity, cognition/capacity, allergy, anticoagulants, infection, baseline neuro status, haemodynamic stability
  • Safety setup: monitoring, IV access, resus equipment, lipid available, trained assistant if possible
  • Technique: ultrasound-guided preferred, identify fascia lata vs fascia iliaca, inject deep to fascia iliaca with adequate volume, incremental injection and aspiration
  • Dosing: choose LA and volume within safe mg/kg, reduce dose for frailty/low weight, avoid exceeding maximum when combined with other LAs (e.g., later spinal infiltration)
  • Aftercare: reassess pain and motor function, falls precautions, document and handover, plan for breakthrough pain
  • Complications: LAST, vascular puncture/haematoma, infection, nerve injury, block failure, provide immediate management plan for LAST
Compare fascia iliaca block with femoral nerve block for hip fracture analgesia. Include anatomy, technique, efficacy, and complications.

Examiner expects a balanced comparison and clinical implications.

  • Anatomy/coverage: FIB targets plane to cover femoral + LFCN (± obturator), femoral block reliably covers femoral nerve only
  • Technique: FIB is plane block with large volume, femoral block is perineural targeted injection, both can be ultrasound-guided
  • Efficacy: both reduce pain, FIB may provide broader cutaneous coverage, obturator involvement is variable (better with supra-inguinal FIB)
  • Complications: both—LAST/bleeding/infection, femoral block may have higher risk of direct nerve trauma, both may cause quadriceps weakness and falls risk
  • Practical: FIB often favoured in pathways due to simplicity and distance from nerve, femoral block useful when targeted femoral analgesia is desired
Outline the management of local anaesthetic systemic toxicity (LAST) in the context of a high-volume fascial plane block.

Must include immediate actions, seizure management, lipid, and modified ALS.

  • Recognise early CNS signs (tinnitus, metallic taste, agitation) progressing to seizures, CVS collapse may occur
  • Immediate: stop LA, call for help, airway management, 100% O2, ventilate to normocapnia
  • Seizure control: benzodiazepines, consider small propofol only if stable, avoid hypoxia/acidosis
  • Lipid emulsion: start promptly per guideline, continue supportive care and treat arrhythmias appropriately
  • If cardiac arrest: high-quality CPR, modify adrenaline dosing, avoid vasopressin and LA antiarrhythmics, continue lipid and prolonged resuscitation if needed
  • Post-resuscitation: ICU/HDU, incident reporting, review dosing/technique and patient factors

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