Ontogeny of gastric emptying patterns in the human fetus.

Objective. Fetal swallowing and gastric emptying contribute importantly to amniotic fluid (AF) homeostasis and fetal gastrointestinal development. We speculated that fetal gastric emptying must be functional early in gestation to prevent rapid increases in AF. We sought to determine the human fetal ontogenic pattern of gastric emptying. Study design. Gastric emptying of eighty normal fetuses at 12–39 weeks was studied. Real-time ultrasound of the fetal stomach was continuously recorded for 1 hour. The gastric area ratio (GAR) was defined as the gastric area divided by the abdominal transverse area. The delta GAR was defined as the change between the maximum and the minimum gastric area ratio x 100 (expressed as percent). A change of the fetal gastric area more than the 10th percentile of the delta GAR at 36–39 weeks was used to define gastric emptying. Results. The 10th, 50th and 90th percentile of delta GAR at 36–39 weeks' was 5.2, 6.5 and 8.7%, respectively. Fetal gastric emptying was detected as early as 12 5/7 weeks of gestation. The proportion of fetuses demonstrating gastric emptying (?>?10th percentile delta GAR) increased with gestational age: 4/33 (12.1%) 12–23 weeks, 3/9 (33.3%) at 24–27 weeks, 8/11 (72.7%) at 28–31 weeks, 12/14 (85.7%) at 32–35 weeks, and 11/13 (84.6%) at 36–39 weeks. Conclusions. Fetal gastric emptying occurs by the beginning of the second trimester, contributing to AF regulation. The increased frequency of gastric emptying in late gestation is likely secondary to increased swallowing, altered fetal behavioral state or endogenous production of gastrointestinal motility factors. [ABSTRACT FROM AUTHOR]