Ultrasound-guided fetal tracheal occlusion

Abstract

Background/Purpose: This study was aimed at examining the feasibility of fetal tracheal occlusion guided exclusively by ultrasonography and at establishing the technical principles of this procedure based on current instrumentation and ultrasound technology. Methods: Time-dated pregnant ewes underwent a small laparotomy and partial uterine exposure. Under real-time ultrasound guidance, a steerable guide wire was fed into the fetal tracheal lumen. An 8F catheter then was fed around the guide wire into the trachea. This was followed by intratracheal placement of a 2F coaxial angiographic catheter, connected to a detachable silicone balloon at its extremity, which then was inflated with saline and delivered locally. Euthanasia was performed at term. Results: Complete tracheal occlusion was achieved in all fetuses (n = 7) intraoperatively. Operating time needed for tracheal occlusion, once access to the amniotic cavity was established, varied widely, but could be as short 1 minute. Tracheal lumen dimensions outgrew balloon diameter in 57.1% of fetuses (4 of 7), resulting in balloon dislodgment in those animals. No balloon rupture was observed. Conclusions: (1) Accurate access to the fetal trachea and local delivery of an occlusive detachable silicone balloon are consistently feasible exclusively under real-time ultrasound guidance with commercially available instrumentation. (2) Balloon dimensions are determining factors of displacement risk and must be selected carefully before tracheal delivery. Ultrasound-guided fetal tracheal occlusion may be a preferable alternative to surgical intervention for treatment of fetal pulmonary hypoplasia.