Safety of chronic fetal vascular access in the sheep model

Objective: Long-term access to the fetal circulation has the potential to open up new perspectives in the treatment of numerous fetal anomalies. The purpose of this study was to investigate the safety of long-term catheterization of fetal placental vessels. Methods: A midline laparotomy was performed in 4 time-mated pregnant ewes at 125 days' gestation (term 145 days). Placental vessels were exposed by a small uterine incision. A specially designed catheter was inserted into a placental vessel over a length of 3 cm, the distal end of the catheter was tunneled underneath the maternal skin and attached to a subcutaneous port implanted in the maternal flank. All pregnancies were allowed to go to term. Results: Ewes and fetuses tolerated the placement of the catheter and port without complications. The catheter remained patent in all cases. All lambs were delivered vaginally at term and did not require resuscitation after birth. No fetal anomalies or growth restriction were noted. Conclusion: The ovine placental vessel can be accessed long term without complication.