Assessment of Spread of Transversus Abdominis Plane Block

For the purpose of assessing the spread of the local anaesthetic after injecting it between abdominal muscles on both sides, the investigators will test if the patient can feel a change in the perception of cold and warm, as well as being pricked with a blunt needle. The investigators will also take several blood samples, together with routine samples, to measure the concentration of the local anesthetic in the blood.