Ultrasound guided High Intensity Focused Ultrasound is technically feasible and safe in occluding placental vessels in early onset twin-twin transfusion syndrome

Shaw, Caroline J., Rivens, Ian, Symonds-Tayler, Richard, Townson, Julia ORCID: https://orcid.org/0000-0001-8679-3619, Owen-Jones, Eleri ORCID: https://orcid.org/0000-0003-0850-4724, Strange, Heather ORCID: https://orcid.org/0000-0002-5758-8445, Playle, Rebecca ORCID: https://orcid.org/0000-0002-2989-1092, Giussani, Dino A., Haar, Gail ter and Lees, Christoph C. 2026. Ultrasound guided High Intensity Focused Ultrasound is technically feasible and safe in occluding placental vessels in early onset twin-twin transfusion syndrome. American Journal of Obstetrics & Gynecology 10.1016/j.ajog.2026.05.006

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Abstract

Background Twin-twin transfusion syndrome is a complication unique to monochorionic pregnancy, where shared placental vascular connections can lead to circulatory imbalance, resulting in preterm delivery and attendant in utero or neonatal or mortality. The only disease modifying treatment is fetoscopic laser ablation of blood vessels, which has attendant risks of invasive intrauterine therapy. Objective In this first-in-human technical feasibility and safety study we investigated non-invasive, ultrasound-guided high-intensity focused ultrasound (HIFU) to occlude placental vascular targets as identified by Color Doppler. The two outcomes were (1) Safety: Number/rate of patients experiencing significant iatrogenic harm, for first 14 days after HIFU and (2) Efficacy: Number/rate of targeted placental vessels which appear occluded at the end of a HIFU treatment cycle, assessed using comparison of colour Doppler imaging of target anastomoses pre- and post-HIFU exposure Study Design: Participants with anterior placenta and early onset twin-twin transfusion syndrome were recruited to a Phase 1a clinical trial with co-primary endpoints of safety and efficacy of vessel occlusion at 12-17+6 weeks of gestational age. Results Ten participants underwent targeted ultrasound-guided High Intensity Focused Ultrasound (HIFU) occlusion of placental blood vessels that connected the two circulations, verified by Color Doppler imaging, in whom 27 of 30 (90%) of targeted placental vessels were successfully occluded by ultrasound-guided high-intensity focused ultrasound. No treatment-related significant maternal or fetal adverse events were recorded, and eighteen of 20 fetuses were alive 14 days post-treatment. Participants expressed positive attitudes towards Ultrasound guided High Intensity Focused Ultrasound, valuing clear and consistent communication and sufficient time to consider participation in the study. Conclusion: In this Phase 1 study, ultrasound-guided High Intensity Focused Ultrasound showed a high rate of successful occlusion of placental vascular targets and no adverse side effects were observed within 14 days of treatment in women with early onset twin-twin transfusion. While clinical efficacy of the technique could not be formally evaluated, five participants required fetoscopic laser and of the pregnancies treated 12 of 20 neonates were alive at discharge.

Item Type:	Article
Date Type:	Published Online
Status:	In Press
Schools:	Schools > Medicine Research Institutes & Centres > Centre for Trials Research (CNTRR)
Publisher:	Elsevier
ISSN:	0002-9378
Date of First Compliant Deposit:	1 June 2026
Date of Acceptance:	13 May 2026
Last Modified:	01 Jun 2026 13:15
URI:	https://orca.cardiff.ac.uk/id/eprint/187340

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