Drinking before endoscopy: milk or water?

The traditional fluid fast prior to endoscopy is unnecessary. We have previously shown that drinking water prior to endoscopy does not affect either the quality of mucosal views or residual gastric fluid volumes when compared to patients undergoing endoscopy after a standard fast. The present study was designed to establish whether milk, which may delay gastric emptying, could also be drunk prior to endoscopy without adverse effect.

Forty-eight patients (mean age 48 years, range 20 to 79) undergoing routine upper gastrointestinal endoscopy after overnight fast were randomized to drink 200 ml of either still mineral water or full fat milk. Endoscopy was performed 90 minutes later, when all residual gastric fluid was aspirated via the endoscope. Volume and pH of gastric aspirate were measured and the quality of the mucosal view at endoscopy recorded as poor, adequate, or excellent.

No difference was shown between water (n = 27) and milk (n = 21) drinkers in residual gastric volume (mean +/- SEM, water vs milk) (16.0 ml +/- 1.5 vs 18.9 ml +/- 2.9) or pH (2.23 +/- 0.14 vs 2.48 +/- 0.14). Of those patients with poor, adequate, or excellent views, 4 of 4, 11 of 12, and 6 of 32 patients, respectively, were milk drinkers (chi-squared test for trend = 21.7, df = 1, p < 0.001), indicating significantly worse mucosal views in the group drinking milk.

Drinking water up to 90 minutes prior to endoscopy is safe, but milk should be discouraged because of suboptimal mucosal views.