“…31,36 Background analgesia included acetaminophen alone, 33,40,49,51 or in combination with NSAIDs (celecoxib 36 or metamizole 52 ), opioids (codeine, 30,34 tramadol, 38,42,45,48 fentanyl, 48,50 or oxycodone 45 ), or both, 31,39 and NSAIDs 37,41,43,47 or opioids (morphine or pentazocine) 29 alone. Four trials 32,35,44,46 did not report baseline analgesia. Opioids (morphine, fentanyl, 41,45 tramadol, 46 and pethidine 43,51 ) were used as rescue analgesia in 15 trials 30,34,36e38,40,41,43e48,50,51 ; combination of acetaminophen and opioids was used in two trials 33,39 and diclofenac in one trial 42 ; six trials 29,31,32,35,49,52 did not report rescue analgesia.…”