Background and aims We describe a novel ultrasound guided peripsoas block (PSB), an anterior approach to lumbar plexus. We corelated cadaveric, clinical and contrast studies.

Methods Institutional Ethics Committee approval and Informed consent was obtained from hospital and patients respectively.

Cadaveric Study. In 5 unembalmed cadavers, psoas and iliacus fascia was exposed.18 G needle was placed under vision below psoas fascia and 20 ml diluted crimson red dye was injected.

Clinical Study. 20 ASA-PS I-II patients underwent open reduction and internal fixation of fracture shaft femur under spinal anesthesia. US-guided PSB was performed at the end of surgery. a linear probe was used to identify infrainguinal psoas tendon with a transverse scan in supine position. on turning the probe longitudinal to psoas tendon, psoas fascia and muscle were identified. 18 G Tuohy needle was introduced below fascia. 20 G catheter was inserted below fascia after injecting 25 ml local anesthetic.

Contrast Study. 24 hours later 30 ml dilute contrast was injected through catheter and CT scan was performed. Images were viewed in axial, sagittal and coronal sections and analysed.

Results Cadaveric Study. 24 hours later after dissection, dye was observed around femoral, lateral cutaneous femoral, genitofemoral and obturator nerve.

Clinical Study. Excellent pain relief was observed for more than 48 hours.

Contrast Study. on analysis of CT scan, the contrast spread in the vicinity of the lumbar plexus elements.

Conclusions The PSB, a novel anterior approach to lumbar plexus is safe, simple approach and can be considered a definite alternative to posterior lumbar plexus approach.