Ultrasonographic analyses of fetal gastrointestinal characteristics and correlations with gestational age and maturity in sheep

Abstract

This observational study aimed to describe the ultrasonographic development of the fetal gastrointestinal (GI) tract in late-gestation ewes and to determine the statistical probabilities of detecting the onset and progressive changes to the GI parameters with advancing gestational age. A grading scale based on studies in other species was applied, specifically for the onset and progressive changes in intestinal wall definition, luminal content characteristics, peristalsis, and segmental dilation. Based on these characteristics, a GI score was assigned to each fetus during serial ultrasonographic examinations until term (median 148 days). With advancing gestational age, progressive maturation and increasing GI scores were observed, with probabilities greater than 90 % for detecting GI scores of 3 and 4 at term. Intestinal wall definition was well-defined with 50 % and greater than 90 % detection probabilities at days 130 and 132 of gestation, respectively. The onset of detectable motility was similar for the forestomach, abomasum, and intestines between 126 and 130 days of gestation. A greater than 90 % probability of detecting motility of the forestomach, abomasum, and intestine were present at 148-, 148-, and 138-days gestation, respectively. As gestational age advanced, intestinal luminal content changed from mixed echogenic to anechoic, and the onset of purposeful segmental dilation progressed from occasional to rhythmic in frequency. At term, there was approximately 90 % or greater probability of observing anechoic luminal content and rhythmic segmental dilation, respectively. Future studies are needed in high-risk pregnancies to determine the predictiveness of fetal GI characteristics as a measure of readiness for birth and potential correlates with neonatal morbidity and mortality in the peripartum period.