When Brioney was diagnosed with a serious condition affecting her unborn twins, she was told she might lose one of them. The condition, called twin-twin transfusion syndrome, meant her two babies were sharing blood unevenly inside the womb. But thanks to an experimental treatment using high-energy sound waves, Brioney and her twins are now doing fine.

Twin-twin transfusion syndrome, or TTTS for short, affects about 10% to 15% of identical twins who share a placenta — the organ that feeds babies in the womb. When twins share a placenta, their blood vessels can connect in ways that cause one baby to get too much blood while the other gets too little. Without treatment, this can cause serious health problems and even death for one or both babies.

The current way to treat TTTS involves surgery. Doctors insert a tiny telescope into the womb and use a laser to close the connected blood vessels on the placenta's surface. This works well, but it requires a small cut in the mother's stomach and can sometimes cause miscarriage.

Now, a small trial at Queen Charlotte's and Chelsea Hospital in London has tested a much gentler approach. Instead of surgery, doctors used high-intensity focused ultrasound — powerful sound waves aimed from outside the body — to block the problem blood vessels. The waves pass through skin and muscle without cutting anything.

The trial included 10 pregnant women with early-stage TTTS. The results, published in the American Journal of Obstetrics and Gynecology, were encouraging. Doctors successfully closed 90% of the targeted blood vessels. All the mothers and their unborn twins had no serious side effects from the treatment. Two weeks later, 18 of the 20 babies were still healthy.

"This is very promising research, confirming for the first time that this noninvasive procedure can be used safely in twin-twin transfusion syndrome," said Professor Christoph Lees, who led the study at Imperial College London.

For Brioney, the 15-minute procedure was a lifeline. "It was such a tough time for us, being diagnosed with such an advanced form of TTTS," she said. "We were facing the very real prospect of losing one of my babies." After the treatment worked, she said, "It was such a relief to find out that both twins were OK."

Researchers are now planning a larger trial with 50 to 100 women to see if the sound wave treatment can become a regular option for TTTS patients.