Modified approach to external oblique intercostal block: a proof-of-concept pilot case series and anatomical evaluation.

Background: Regional anesthesia techniques that provide analgesia to the entire lateral abdomen are limited. We present a modified external oblique intercostal block for complete lateral abdominal analgesia with a single injection.

Case: We performed a modified version of the external oblique intercostal block unilaterally at the tenth rib along the mid-axillary line in three patients undergoing robot-assisted partial nephrectomy (two single injections, one catheter placement) and tested the technique on a cadaver with 20 ml of dye bilaterally. All patients reported good postoperative pain relief without complications and had consistent sensory coverage of the T8-T12 dermatomes from the anterior-to-posterior axillary line. Anatomical assessment confirmed consistent bilateral staining of the lateral cutaneous branches T8-T12.

Conclusions: The initial clinical success and anatomical findings of the modified approach to the external oblique intercostal block suggest that this technique may be an effective option for lateral abdominal analgesia.