Randomization and blinding
All enrolled patients were randomized (1:1) to receive TTMP block (TTM group) or placebo (PLA group) using a computer‐generated random number and was kept in the sealed envelopes by the attending anaesthesiologist. Another researcher prepared the trial medication (the normal saline or 0.30% ropivacaine) according to the group allocation of the sealed envelopes. The operator who performed bilateral TTMP blocks did not know whether the fluid is normal saline or ropivacaine. The treating physicians, patients, nurses, anaesthesiologists and the investigators were blinded for treatment allocation. This was a double‐blind, randomized, controlled study.