INTRODUCTION: Fetal lower urinary tract obstruction (LUTO) affects approximately 1 in 5,000 pregnancies and can lead to renal failure, oligohydramnios or anhydramnios, and pulmonary hypoplasia. Mortality ranges from 60% to 80% overall, and survival in advanced cases falls to less than 5–20% without intervention. The only FDA-approved fetal shunt has a 50% dislodgement rate and is no longer manufactured. A more secure device is needed to improve outcomes in LUTO. METHODS: A novel shunt was designed using shape-memory nitinol thermoset into a unique configuration. The device can be straightened at room temperature for delivery through a cannula and upon exposure to body temperature, transitions to a superelastic state, activating the anchoring shape to secure flush in place. Force testing was conducted using a 1.8-mm silicone wall model representing fetal bladder and abdominal tissue. The shunt was inserted through a preformed opening, deployed, heated to body temperature, and then subjected to removal force measurement using a custom 3D-printed testing apparatus. RESULTS: The new shunt required an average of 0.8 pounds-force to dislodge. This removal strength is more than 15 times higher than the 0.05 pounds-force reported for the Harrison shunt. No structural damage occurred to the device or simulated tissue during testing. CONCLUSIONS/IMPLICATIONS: The nitinol flower shunt demonstrated substantially improved retention compared with the historical standard and offers a promising, secure alternative that could reduce mortality, improve fetal development, and restore hope for full-term pregnancies in this high-risk population.
Clark et al. (Thu,) studied this question.