Macroscopic and histopathologic findings in a laparoschisis model in fetal sheep: comparisons with gastroschisis in human fetuses and implications for prenatal interventions.

ABSTRACT

PURPOSE: In order to further define the challenges, minimally invasive fetal surgery will have to overcome human fetuses with gastroschisis. The purpose of this study was to compare macroscopic and histopathologic characteristics of experimental laparoschisis in sheep fetuses with actual cases of gastroschisis from a postmortem series of human fetuses. METHODS: Employing fetoscopy, we created a laparoschisis model in eight fetal sheep between 74 and 92 days of gestation (median 86.5 days). Twenty to 31 days after fetoscopic creation of fetal laparoschisis, six surviving fetuses were harvested for macroscopic and histopathologic assessments of the experimental lesion. These findings were compared to those of ten human fetuses with gastroschisis after termination of pregnancy. RESULTS: In the six sheep fetuses, both macroscopic and histopathologic intestinal changes achieved by this animal model resembled those of the human fetuses with gastroschisis. The surface of the intestine, liver and stomach exposed to the amniotic fluid was covered by a thick pseudocapsule made up of reactive fibroblasts and a dense capillary network. Parts of the capsule showed a foreign body-type reaction. CONCLUSIONS: Macroscopic and histopathological findings in a new minimally invasive laparoschisis model in sheep resemble those found in human fetuses with gastroschisis. The new model seems therefore suitable for assessing the potential of prenatal minimally invasive fetoscopic interventions in this condition.