TRANSUTERINE PUNCTURE OF THE FETAL STOMACH PROVIDES ACCESS TO THE SMALL-BOWEL IN THE RABBIT

The prevention of perinatal complications of congenital gastrointestin al (GI) diseases such as cystic fibrosis may require prenatal treatmen t. New Zealand White rabbits were evaluated as a potential animal mode l to study gastrointestinal anatomy and transit in the fetus. The leng ths of the GI tract of fetuses at 21/31 and 28/31 days gestation were established, and gastric volume was measured. Gastric volume at 28 day s gestation averaged 2.6 mL, adequate to permit instillation of a solu tion into the fetal stomach. A study was then carried out to establish gastric emptying and delivery of the solution into the small bowel. U sing ultrasound guidance, the stomachs of 26 fetuses from 7 litters we re punctured and 0.5 mL of dilute barium was injected. A cesarean sect ion was performed 4 h later and the progression of barium though the G I tract was measured. In 18/26 (69.2%) of the fetuses barium was succe ssfully delivered to the lumen of the stomach. In these 18 fetuses, ba rium progressed to the duodenum in 15 (58%), the jejunum in 13 (50%), and the ileum in 8 (31%). The stomach of the 3.5- to 4-week-old fetus is large enough to allow transuterine delivery of a solution of dilute barium. Gastric and intestinal motility in the 25-day-old rabbit fetu s is coordinated and results in delivery of barium to the small bowel in 50% of animals successfully injected. The results suggest that the rabbit is an acceptable model for the study of gastrointestinal delive ry of therapeutic drugs or genes to the fetus.