Temporal changes in gastric volume in the human fetus in late pregnancy.

Disturbed fetal gastrointestinal tract function is associated with hydramnios and may be a marker of later gastrointestinal disease. We investigated gastric motor function in the human fetus to establish the range and rate of fluctuation of gastric volume. Two pairs of orthogonal gastric diameters were measured at 5-min intervals for 1-h periods using a linear-array ultrasound scanner in 12 fetuses in late pregnancy (26-40, median 35.5 weeks gestation). A gastric volume index (GVI) was calculated. Maximum absolute gastric volume index correlated significantly with gestational age. The minimum gastric volume index as a percentage of the maximum (0-60.4%, median 28.1%) showed that marked changes in gastric dimensions occur. Filling (41.5-74.1, median 62.6 degrees) and emptying (46.6-80.9, median 61.7 degrees angles were calculated for the longest continuous filling and emptying periods using a linear model, and showed no difference in the rates of filling and emptying. Peak-to-peak and trough-to-trough durations suggested a periodicity of 35-55 min. Investigation of the development of normal fetal gastric motor activity may lead to a better understanding of postnatal adjustment to enteral feeding, and may provide a diagnostic method for antenatal diagnosis of gastrointestinal functional disturbances.