[Changes in the pH and volume of gastric contents during pregnancy and labor]

We measured the volume and pH of gastric contents of 97 patients after induction of anaesthesia. The patients were divided into 3 groups: group I (N = 39): elective cesarean section, group II (N = 44): elective gynecological surgery, group III (N = 14): emergency cesarean section. The study was undertaken to ascertain whether pregnancy and labour would modify the volume and mean pH of gastric contents. Mean pH of gastric contents in the 3 groups were respectively 2.57; +/- 0.23; 3.21 +/- 0.29; and 2.77 +/- 0.42. There were no significant differences between the groups: Pregnancy and labour do not influence gastric pH. As far as gastric volume is concerned there is a significant difference between Group I and III (p less than 0.01) and Group II and III (p less than 0.01).