Robotic System Aims to Improve Surgery for High-Risk Twin

A new robotic platform could make a complex, life-saving surgery for a high-risk twin pregnancy condition easier and more precise. The system, developed by researchers at ETH Zurich and doctors at the University of Zurich, is designed for treating twin-to-twin transfusion syndrome (TTTS).

In Switzerland, about 2,400 children are born as twins annually. When twins share a placenta, they are connected by blood vessels. An imbalance in this shared circulation, known as TTTS, is life-threatening for both fetuses. It affects approximately 20 to 30 women a year in the country. The only effective treatment is a highly complex laser operation performed by a handful of specialists globally.

Currently, surgeons use a rigid fetoscope-a delicate endoscope for pregnant patients-to guide a laser to seal the connecting blood vessels in the placenta. Depending on the placenta's position, it can be extremely difficult to reach all the affected vessels with a rigid instrument.

Magnetic Control for Greater Maneuverability

In response, the team created a flexible fetoscope just 3.2 millimeters in diameter. Its tip contains small magnets. Three large electromagnets outside the patient's body generate a controllable magnetic field, allowing surgeons to bend the instrument's tip. The magnetic field is harmless. The principle is similar to a compass needle aligning with Earth's magnetic field.

Lead author Michelle Mattille, a postdoctoral researcher, stated they achieved a bend of up to 173 degrees. "This means we can easily reach even the hard-to-access vessels," Mattille said. The work is detailed in a paper published in the journal Science Robotics.

Handling with a Panoramic View

A second key component is a panoramic view. During standard minimally invasive surgery, surgeons see only a small section through the endoscope and must memorize vessel paths. The new system combines individual endoscopic images in real time to form a two-dimensional panoramic map. A surgeon can select a target on this map, and the fetoscope handles there automatically.

Doctors can take manual control at any time using a PlayStation game controller. Software translates the desired movement into a corresponding change in the magnetic field. Mattille noted the robotic procedure differs significantly from conventional surgery. "Even the very steady hand of an experienced surgeon causes the fetoscope to wobble slightly." she explained.

In experiments, participants hit simulated targets far more accurately with the robotic system. Mattille reported that with the robotic system, the deviation was typically 140 micrometers, making it more than four times more precise than comparable conventional instruments.

Critical Testing Outside the Laboratory

A key step toward clinical use was an experiment on a pregnant ewe. This was the first test outside a controlled lab environment, requiring the team to contend with the animal's breathing, heart rate, cloudy amniotic fluid, and a moving fetus. We spent a year preparing for the approximately three-hour animal experiment. Mattille said.

Mattille developed the platform during her doctoral work with researchers from ETH Zurich and surgeons Nicole Ochsenbein of the University Hospital and Ueli Moehrlen of the University Children's Hospital Zurich. Professor Quentin Boehler also played a key role.

Following successful tests, the team plans to further develop the platform for human use. This requires more safety assessments and refining algorithms to create a robust clinical system. They are also developing additional assistance functions for surgeons.

The technology could have applications beyond fetal surgery, such as assisting navigation during gastroscopies and cystoscopies while mapping examined areas. Mattille noted the requirements differ, as these procedures involve mapping a three-dimensional cavity rather than a relatively flat placental surface. The successful animal trial marks an important milestone toward robot-assisted procedures in fetal surgery.