Spread of injectate after ultrasound-guided subcostal transversus abdominis plane block: a cadaveric study

Ultrasound-guided transversus abdominis plane (TAP) block can be performed using a subcostal technique. This technique was simulated using dye injection in cadavers in order to determine segmental nerve involvement and spread of injectate using either single or multiple-injection techniques. Dye most commonly spread to affect T9 and T10 nerves with the single injection technique and T9, T10 and T11 with multiple injections. The median (IQR [range]) spread of dye was 60 (36-63 [32-78]) cm(2) using the single-injection technique and 90 (85-96 [72-136]) cm(2), in the multiple-injection technique, and this difference was statistically significant (p = 0.003). These results indicate that ultrasound-guided subcostal TAP block will involve nerve roots T9, T10 and T11 and that a multiple-injection technique may block more segmental nerves and increase spread of injectate.