World-first ultrasound procedure saves twins in womb from rare disorder

Doctors used ultrasound-guided high-intensity focused ultrasound, or HIFU, to block abnormal placental blood vessels in identical twins Nancy and Margo before 18 weeks of gestation. Twin-to-twin transfusion syndrome, or TTTS, is a rare and often dangerous complication that develops when twins share one placenta and blood flow between them becomes unbalanced.

TTTS affects about 10% to 15% of identical twins who share a placenta, or roughly 300 to 400 pregnancies each year in the UK. One twin can be deprived of blood while the other receives too much, a shift that can cause serious harm or death if it is not treated. The standard intervention has usually been fetoscopic laser surgery, an invasive procedure that seals off abnormal vessels and carries its own risks.

The trial tested whether HIFU could do the same job without entering the womb. In 10 women, the study achieved successful occlusion of targeted placental vessels in 90% of cases, with no significant maternal or fetal adverse events in the short term. The treatment did not end the need for surgery in every case: half of the women still required subsequent fetoscopic laser treatment, and 60% of fetuses survived to discharge.

Nancy and Margo were born healthy after the procedure. The twins were delivered at nearly 34 weeks and each weighed more than 3 pounds. Their mother, Brioney Garrett, called them her “miracle twins” and said, “We were in a very dire situation,” adding that she still counts her blessings every day.

The UK Health Research Authority identified the work as the first in-human clinical study of ultrasound-guided HIFU to treat TTTS diagnosed before 18 weeks, while Imperial called it the world’s first phase 1 trial of HIFU as a non-invasive treatment for the condition.