World-First Study Shows HIFU Is Safe and Promising for Treating Twin-to-Twin Transfusion Syndrome
核心洞察
A first-in-human study confirms high-intensity focused ultrasound (HIFU) can safely block abnormal placental blood vessels in early-onset twin-to-twin transfusion syndrome (搜索) (TTTS).
The non-invasive procedure successfully blocked blood flow in 90% of treated vessels with no adverse side effects, though half of the 10 participants required further treatment.
Researchers are now planning a larger trial of 50 to 100 women to determine whether HIFU can stabilize or reverse TTTS as an alternative to invasive laser therapy.
A pioneering non-invasive procedure using high-intensity focused ultrasound (HIFU) has been shown to be safe and has the potential to treat twin-to-twin transfusion syndrome (搜索) (TTTS), according to a world-first study published in the American Journal of Obstetrics and Gynecology.
Led by Professor Christoph Lees at Imperial College London and Imperial College Healthcare NHS Trust, the first-in-human feasibility study involved 10 pregnant women from the UK and Europe diagnosed with early-onset TTTS. The research marks the culmination of over 15 years of collaborative work, with the HIFU device designed and built by a team from The Institute of Cancer Research (ICR) in London.
"This is very promising research, confirming for the first time that this non-invasive procedure can be used safely in twin-twin transfusion syndrome," said Professor Lees, head of fetal medicine at Imperial College Healthcare NHS Trust and professor of obstetrics at Imperial College London. "That's really encouraging, because at present we are only able to treat this condition by using a more invasive method which has its own risks."
How the HIFU Procedure Works
TTTS occurs in 10–15% of identical twin pregnancies that share a placenta, affecting between 300 and 400 pregnancies each year in the UK. The condition arises when blood flow between the babies becomes unbalanced: one twin receives too much blood while the other receives too little, potentially leading to organ failure or death for both if left untreated.
The current standard of care involves inserting a fetoscope into the womb and using a laser to seal the shared blood vessels on the placenta's surface. While often successful, this invasive approach carries risks including miscarriage.
In the HIFU study, researchers used Doppler ultrasound to identify the tiny placental blood vessels connecting the twins' circulations. A beam of high-energy sound waves, generated by a device placed outside the mother's body, was then directed to precisely heat and block blood flow through those vessels. The procedure was performed between 12 and 17 weeks of pregnancy.
Professor Gail ter Haar, Professor of Therapeutic Ultrasound at the ICR, explained: "High levels of ultrasound heat tissue, so we can essentially cook the cells – and with the focused intensity, we can do this very specifically to the cells and structures of interest, including blood vessels."
Key Findings and Limitations
The study found that the HIFU procedure successfully blocked blood flow in 90% of the placental blood vessels treated, and no adverse side effects were reported among the women or their unborn twins. The treatment was received positively by participants.
However, because the study was designed to assess safety and feasibility rather than clinical efficacy, half of the 10 women required further treatment, including laser ablation. Of the 20 twin babies involved, 12 survived following the treatment.
The researchers have not yet established whether HIFU can stabilize or reverse TTTS. A larger clinical trial involving 50 to 100 women is now being planned to determine whether the procedure can serve as a less risky and equally or more effective option compared to current invasive methods.
A Patient's Perspective
Brioney Garrett, who lives in Cornwall, was diagnosed with advanced TTTS at her 12-week scan in 2022. After learning that laser treatment was not an option for her, she was referred to Queen Charlotte's and Chelsea Hospital, where she enrolled in the HIFU trial.
"The procedure itself took about 15 minutes, with a few follow-up scans over the next few weeks," Brioney said. "It was such a relief to find out that the treatment had worked a couple of weeks later and that both twins were OK."
Her daughters, Margo and Nancy, are now nearly four years old and about to start primary school. "I'm so grateful to the hospital team and to everyone involved in the research. They saved my girls' lives," she added.
Broader Support and Next Steps
The study was funded by a £2.2 million grant from the Medical Research Council (MRC) awarded in 2017, with additional support from The Wiseman Trust, the UK Focused Ultrasound Foundation, and commercial partner Canon Medical Systems Ltd. Patient support groups including Twins Trust and the Twin-Twin Transfusion Foundation in the US also contributed.
Dr Adam Babbs, Associate Director of Translational Research at UKRI MRC, said: "This study provides important proof of concept that high intensity focused ultrasound could offer a non-invasive way to intervene earlier, with the potential to improve outcomes for affected babies."
Helen Peck, head of healthcare engagement and research at Twins Trust, described the approach as potentially "a turning point," adding: "Any procedure that is non-invasive and can potentially identify TTTS earlier and improve outcomes for our families with this life-threatening condition could be a turning point."
Professor Lees and his team are now preparing for the next phase of research. "We hope to follow this study with a bigger clinical trial with 50 to 100 women, so we can determine if it can successfully treat TTTS and understand whether this procedure could be a less risky and equally or more effective option for women and their twin babies," he said.