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Intercostal blocks provide good postoperative analgesia for inguinal hernia repair, orchidopexy and varicocele/hydrocele repair.
Anatomy
Source: USRA
The iliohypogastric and ilioinguinal nerves form part of the lumbar plexus, arising from T12/L1 nerve root. At the lateral border of quadratus lumborum muscle, the nerves pierce the lumbar fascia to run anteriorly and medially between transversus abdominus and internal oblique muscles.
- Iliohypogastric nerve perforates the internal oblique muscle to lie deep to external oblique muscle at ~2cm medial to ASIS. It then runs medially to pierce external oblique aponeurosis ~3cm above superficial inguinal ring, supplying the skin above pubis and medial half of inguinal ligament.
- Ilioinguinal nerve perforates the internal oblique muscle inferior and medial to iliohypogastric nerve, traversing the inguinal canal to emerge from the superficial inguinal ring. It supplies the skin over the root of the penis and scrotum, and structures within the cord.
Complications: Block of femoral nerve, block of lateral cutaneous nerve of thigh, bowel/viscus perforation, subcutaneous/pelvic haematoma, nerve injury, intravascular injection
Technique
- Position patient supine
- Insert needle perpendicular to skin at 1cm medial and 1cm inferior to ASIS
- As the external oblique muscle is pierced, a 'click' or 'pop' is felt, and 6-8ml of LA injected to block the iliohypogastric nerve
- Advance needle further to pierce the internal oblique muscle. Another 'click' or 'pop' is felt, and a further 6-8ml of LA injected to block the ilioinguinal nerve
To do a field block for hernia repair, in addition to the above, further injections are used to block the cutaneous branches of the subcostal nerve and genital branch of genitofemoral nerve:
Just anterior to ASIS, infiltrate 3-5ml of LA subcutaneously in a fan-shaped manner. Similar injection made over pubic tubercle. Finally, inject 5ml of LA into fascial coverage of spermatic cords once exposed, to block genitofemoral nerve and sympathetic fibres.
References
Warman P, Conn D, Nicholls B, Wilkinson D. Regional Anaesthesia, Stimulation, and Ultrasound Techniques. Oxford Specialist Handbooks in Anaesthesia.
Author:
Ms Yanyu Tan
| Speciality:
Anaesthetics/ICU
| Date Added:
09/11/2018
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