Psoas-Compartment-Nerve-Block

Updated : December 17, 2025

Psoas Compartment Nerve Block, also known as Lumbar Plexus Block, is another method of regional anesthesia commonly applied for patients who require surgical operation or those who suffer from chronic pain in the lower limbs. This block aims at the lumbar plexus, a cluster of nerves in the psoas muscle situated in the lower back region near the spine.

Chronic Pain Relief: In the situations like lumbar radiculopathies where patient suffers from chronic pain in lower back and lower limbs.
Diagnostic Purposes: To diagnose the cause of the pain in the lower back or legs by anesthetizing selected nerves for a particular time.
Therapeutic Purposes: To give long-term pain control in situations like meralgia paresthetica or complex regional pain syndrome.
Preoperative Analgesia: Because of the requirement to minimize the usage of general anesthesia and to decrease the intraoperative and postoperative use of opioids.

Patient Refusal: In this case, if the patient does not wish to go through the procedure.
Infection: Infection where the injection has been given or when the infection spreads through the entire body.
Coagulopathy: Patients with bleeding disorders or on any other anticoagulation therapy seem to be at a higher risk of bleeding episodes.
Pre-existing condition/allergy: Known allergy to local anesthetics or other drugs used in the procedure.

Needles
25 gauze needles
Nerve Stimulator
Ultrasound Machine
Sterile ultrasound probe cover
Local anesthetic Solutions
Common choices include bupivacaine, ropivacaine, or lidocaine
Syringes of various sizes
Sterile Equipment
Pressure Transducer
Extension Tubing
Emergency Equipment
Monitoring Equipment

Patient Assessment:

Summarize all information concerning the patient, all the current medications, allergies, and any conditions which can be a contraindication.

Informed Consent:

Discuss the process, advantages, drawbacks, and available choices to the patient.

Obtain written informed consent.

Pre-Procedure Instructions:

Inform the patient not to consume any food and or beverages especially before the operation if sedation is going to be used, usually for not less than 6-8 hours before the operation.

Preoperative instructions about medications should be followed for patients, such as which ones should be taken, and which ones should be avoided.

Position the patient in a lateral decubitus position.

Make the patient comfortable and ensure their heads and limbs are in the correct positions.

Step 1-Patient Preparation:

Obtain informed consent.

Place the patient in the lateral decubitus position. The patients’ knees and hips shall be slightly flexed to enable easy palpitation of landmarks as need be.

Check, and determine, the patient’s pulse, blood pressure, oxygen levels, and other physiological parameters whilst obtaining peripheral IV access.

Wash the skin with an antiseptic solution and drape the area.

Step 2-Landmark Identification:

Localize the spinous processes representing the midline and then determine the iliac crest.

Palpate the iliac crests and draw a line joining them, this line known as Tuffier’s line commonly intersects the L4 spinous process.

Make sure that the L4 spinous process is visibly located and then, using a pen, mark the skin 3-5 cm away from the proposed block-side.

Step 3-Needle Insertion:

Make a small incision at the marked site on the skin and subcutaneous tissue, then inject a local anesthetic.

Introduce the Tuohy needle in parallel to the skin and slide it slowly forward till it touches the L4 transverse process. This happens typically at 4-6cm from the epidermis/dermis junction of the skin.

After contacting the transverse process, withdraw the needle a little, rotate it in the cephalad or caudad direction, and advance again until the transverse process is passed. The total depth might be between 8 to 12 cm.

If a nerve stimulator is to be used, set it to cause a current of 1. 0 to 1.5 mA. Check for the twitching contractions of the quadriceps in the leg, which would illustrate that the femoral nerve has been stimulated.

When doing the regional blockade with ultrasound, identify the psoas muscle and the lumbar plexus and then introduce the needle, observing the path.

Step 4-Injection:

Aspirate for blood or cerebrospinal fluid, following verification of the correct positioning of the needle by either nerve stimulation or ultrasound guidance.

Injection of a small test dose of the local anesthetic to indicate the appearance of signs related to intravascular or intrathecal injection, 1-2 ml.

If negative, inject the remaining dose of local anesthetic slowly while continuously aspirating to avoid intravascular injection. The total volume is typically 20-30 ml.

Step 5-Post-Procedure Care:

Supervise the patient for the manifestation of local anesthetic toxicity.

To evaluate the block’s efficacy, it is essential to test for the absence of sensation and movement in the given region.

Ensure follow-up of the patient after surgery and treat the pain as and when it occurs.

Infection: There is always the potential for infection with any invasive procedure.
Nerve Injury: The nerves in the psoas compartment are vulnerable to direct trauma, which could lead to nerve injury, weakness, numbness, or chronic pain.
Vascular Injury: Blood vessels may be inadvertently punctured, leading to bleeding or hematoma formation.
Retroperitoneal hematoma: Bleeding may occur into the retroperitoneal space that could be life-threatening and require surgical intervention.
Visceral Injury: Visceral injury is a risk due to the proximity of these structures to the psoas compartment.
Allergic Reactions: To the injected local anesthetic or any other drug used in block conduction.
Transient Femoral Nerve Palsy: This can lead to a temporary inability to extend the knee or flex the hip.