Relationship between stomach contents and analgesia in labour.

The volume of stomach contents found in patients undergoing Caesarean section was studied. The largest volumes were found in patients who had received pethidine analgesia and the smallest volumes in patients who had received either extradural analgesia or no analgesia. Intermediate volumes were found in patients who had received pethidine in addition to extradural analgesia. Pethidine, rather than the emotional stress of labour, was thought to cause gastric retention. Patients having elective Caesarean sections had considerably less gastric retention than patients in labour.