Feasibility of minimally invasive intrauterine fetal access in a monkey model

Purpose: We evaluated new intervention techniques and surgical instruments in a fetal monkey model to determine improvements that would be useful for early intrauterine intervention. Our findings may be helpful in the future for treating select cases of severe prenatal obstructive uropathology. Materials and Methods: in a series of experiments on 18 pregnant rhesus monkeys (Macaca mulatta) at mid trimester we assessed various endoscopic intra-amniotic access techniques as well as morbidity, mortality and possibilities for fetoscopy. Results: In all 18 fetuses adequate fetoscopy was possible with no maternal mortality. Of the 18 pregnancies 14 went to term with no early or late postoperative complications. Technical improvements changed the intrauterine access technique from open placement of trocars to the use of the Seldinger technique, gun introduction of needles with small caliber sheets and small caliber introduction trocars, resulting in minimal amniotic membrane separation. Various rigid and flexible endoscopes were evaluated for fetoscopy and up to 3 cannulas were placed. No change in the fetal growth pattern was observed on postoperative ultrasound. Subsequent pregnancies occurred during this study period, and there were no acceptance problems of the newborns by the mothers. Conclusions: New techniques have led to improved intrauterine fetal access. Morbidity mainly depends on the disruption of amniotic membranes, which has an important preterm role. Adapted endoscopes and other instruments offer new possibilities for fetal diagnosis and therapy in the future. Our primate model seems to be suitable for evaluating these new techniques before they are used in a clinical setting.