Each year, about 250,000 Americans undergo sleeve gastrectomy, one of the most common weight-loss operations in the United States. For most patients, recovery is uneventful.
But for a small share — between one and three percent in routine cases, and as many as one in ten in revision surgeries — the procedure can leave behind a gastric leak, in which fluid escapes from the stomach and forms an abscess.
Treating those leaks can be a long process. Doctors usually rely on endoscopic internal drainage, threading a small plastic tube called a double-pigtail stent through the stomach wall so the fluid can drain. But the devices typically used are built for bile ducts, not for the oddly shaped cavities created by gastric leaks.
That mismatch matters. The stents can slip, drain slowly and require repeated procedures before the leak resolves.
Now, researchers at New York University say they have found a better approach by changing the shape of the stent itself. Their findings have been published in Advanced Healthcare Materials .
Their prototype, called the Lily stent, is the first product of a design framework the researchers named PETALS, for Personalized Endoscopic Transmural Abscess Leak Solution, a mathematical approach to optimizing drain shape for complex biological fluids that the team says could be applied beyond gastric leaks to other drainage challenges in the body.
Using computer simulations and mathematical modeling, the researchers found that length and inner diameter mattered most, while the curled anchoring ends had little effect on fluid flow. Counterintuitively, a wider tube does not drain better. Increasing the inner diameter shrinks the gap around the outside of the stent, where most of the fluid actually travels. That means exterior topography, not interior volume, is the primary driver of drainage performance.
That insight is the foundation of the PETALS framework. By mathematically optimizing the outer surface geometry for the viscosity and pressure of gastric fluid, the team arrived at their new stent, a six-part structure that creates more effective routes for fluid to move around the device.
"The key insight is that the geometry of the tube's cross-section, especially the exterior surface, fundamentally determines how fast fluid moves through and around it," said Khalil Ramadi , an assistant professor at NYU Abu Dhabi and NYU Tandon School of Engineering and the study's senior author. "We're not just making it out of a different material. We're changing the shape to make it work better."
If the results hold up beyond the lab, the payoff could be meaningful. Roughly 2,500 people in the United States require treatment each year for gastric leaks after bariatric surgery. Faster drainage could shorten recovery and reduce the need for repeat procedures, easing both the burden on patients and the cost of care.
The device is still early in development. So far it has been tested only in simulations and benchtop models. Animal studies will be needed before it can move closer to clinical use.
The Lily stent also proved more flexible than the commercial polyethylene device it is meant to replace, an attribute surgeons associate with better patient tolerance and reduced tissue damage. In short-term animal studies, tissue surrounding the implanted material showed no significant difference from tissue around standard polyethylene, an early indicator of biocompatibility.
The researchers note that the Lily design's constant cross-section geometry would allow it to be manufactured by conventional extrusion methods, without requiring hospitals to invest in 3-D printing infrastructure.
"Our work shifts the focus from just placing a stent to engineering its function at a structural level," said Parima Phowarasoontorn, a research assistant in Ramadi's NYU Abu Dhabi lab and the paper's first author. "Instead of simple tubes, we introduce cross-sectional designs that improve drainage while remaining compatible with existing endoscopic delivery procedures."
The Lily stent research follows Ramadi's lab's announcement of the CORAL capsule, an ingestible pill whose coral-like structure traps bacteria from the small intestine, enabling researchers to study microbial communities that contribute to certain diseases. Both devices draw on nature's own geometry to solve medical problems that conventional tools have struggled to address.
