The ultrasound-guided transversus abdominis plane (TAP) block is used to treat postoperative pain after abdominal surgery. Abdominal wall sensory nerves are anaesthetised by injecting local anaesthetics into the neurofascial plane between the internal oblique and the transversus abdominis muscles. Sensory assessment of a TAP block may guide the decision on the extent of the block. The purpose of this study was to investigate if the dermatomal extent of sensory blockade after injection of 20 ml 0.5% ropivacaine bilaterally into the TAP can be assessed using cold and pinprick sensation.