Effects of preoperative fasting on morbidity and gastric contents in patients undergoing day-stay surgery.

The effects of overnight fasting on gastric contents and on the symptoms associated with fasting were studied prospectively in female outpatients. Group A (n = 66) were patients scheduled for first trimester therapeutic abortion; group B (n = 66) were scheduled for minor gynaecological surgery. It was demonstrated that overnight fasting (15 +/- 3 h) did not guarantee an empty stomach (volume 22 +/- 13 ml) and that gastric acidity was high (pH 1.6 +/- 0.5). Gastric volumes and pH were the same in both groups. Group A patients had a higher incidence of preoperative nausea and vomiting (P less than 0.001). Before anaesthesia, 50% of all patients had symptoms of moderate to severe hunger, while 44% of patients had symptoms of moderate to severe thirst. Neither the severity of symptoms of fasting nor the duration of fast correlated with gastric volume or pH. Patients in group A had significantly greater symptoms of hunger; however, they also had fasted for significantly longer (P less than 0.002).