Therein lies one of the challenges of TAP blocks in my opinion. Unless you are doing them as a rescue block where every patient in pain is their own control group (pain before vs. pain after), pre-op TAP block placements are hard to assess for success. Sometimes you get perfect spread and they have significant pain in the PACU, and sometimes the image is terrible and they are pain free. And pain scores are not a perfect measure of success for pre-op placed TAP blocks since visceral pain is not covered by the block and is like a confounding variable. So pre-op TAP blocks are a bit of a leap of faith each time they are placed; we rely on published data to demonstrate their benefits in general while not always being able to assess their success in individual patients.