Epidural analgesia for post-caesarean pain relief: a comparison between morphine and fentanyl.

In 20 post-operative patients who had undergone caesarean section, morphine 2 mg or fentanyl 75 micrograms in 0.9% saline were given epidurally in a randomized study, to compare their effectiveness in providing post-operative pain relief and the incidence of untoward reaction. There was a faster onset of action (P less than 0.01) and the quality of pain relief was substantially better after epidural fentanyl (P less than 0.01). However, the duration of action was markedly longer after epidural morphine (P less than 0.01). There was a significantly greater incidence of urinary retention after morphine administration (P less than 0.05). It is suggested that fentanyl gives better relief of pain than morphine when given epidurally.