Assessment of Spread of Transversus Abdominis Plane Block After Administration of 20 ml Ropivacaine 0,5% Bilaterally

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.