Influence of preoperative gastric aspiration on the volume and pH of gastric contents in obstetric patients undergoing caesarean section.

Aspiration of gastric contents, the most common anaesthetic cause of maternal mortality, is decreased by emptying of the stomach and the use of antacids and H2-receptor antagonists. One hundred and eighty-three mothers presenting for emergency Cesarean section were allocated to three groups. In group 1, the stomach was emptied before operation via an orogastric tube and thereafter 30 ml of sodium citrate 0.3 mol litre-1 was ingested 5-15 min before induction of general anaesthesia (our usual practice). Group 2 received only 30 ml of sodium citrate 0.3 mol litre-1. Group 3 received ranitidine 50 mg i.v. before operation, 5-15 min before induction of anaesthesia, in addition to sodium citrate. Our results show that preoperative gastric emptying with an orogastric tube followed by sodium citrate is preferred if anaesthesia should be induced 15-20 min later. However, the use of ranitidine and sodium citrate is preferred at subsequent times. Although our data show that preoperative gastric emptying decreased the mean intragastric volumes before Caesarean section, the number of patients at risk of acid aspiration was not reduced. In view of these findings and the unpleasantness of orogastric intubation, we suggest that routine preoperative gastric aspiration via an orogastric tube is not justified, although the manoeuvre should still be used following a recent meal.