Ureteral Stent Electromagnetic Removal (USER) Device for Pediatric Patients - PROJECT SUMMARY
Significance: Over 5,000 children have ureteral stents placed each year to alleviate an obstruction caused by
a kidney stone between the kidney and the bladder or to maintain urinary flow following reconstructive or
transplant surgery. In adults, a dangler string that is threaded through the urethra and secured to the skin is
simply pulled at a follow up visit to remove the stent, but this string is removed in children to prevent infection
and accidental removal. Children must then undergo an invasive procedure via cystoscopy, which consists of
inserting a scope into the urethra under general anesthesia to pull the stent out. Recent evidence suggests
early overexposure to anesthesia has been associated with an increased risk of long-term cognitive deficits in
language and abstract reasoning. As such, medical solutions that can provide the same results as traditional
procedures without general anesthesia are being sought out in all areas of medicine, but particularly in
pediatrics. Innovation: The Ureteral Stent Electromagnetic Removal (USER) device is a non-invasive stent
removal system that uses a magnetic bead and an external electromagnet to smoothly guide the stent out of
the patient's body without the need for general anesthesia. The magnetic bead is coated in a biocompatible
material and is secured to the lower stent curl by tying the bead to the dangler string and cutting it short so that
the bead and string remain in the patient's bladder. The electromagnet is held in a patient-friendly casing with
smooth surfaces and handles for ease of manipulation. This solution shortens the removal process, reduces
the cost of the procedure and minimizes the risk of cognitive deficits in children from early overexposure to
general anesthesia. Approach: In this SBIR Phase I project, Fannin Innovation Studio will optimize the
prototype device design and test it in benchtop, animal, and cadaver models of the urinary tract. The Specific
Aims of this project are: (1) Build and characterize a prototype USER device including magnetic beads and
electromagnet with adjustable field strength. The performance of various magnet geometries, materials, and
coatings will be characterized and implemented into the prototype. The field geometries of the electromagnet
will then be evaluated and a user interface to control the magnetic field strength will be built. (2) Test the
prototype USER device in benchtop, animal, and cadaver urinary tract models. The previous benchtop model
will be refined to be more anatomically representative of the pediatric urinary tract with respect to material
elasticity and surface characteristics. The prototype will then be tested in porcine and cadaver models to
assess for signs of tissue damage and further demonstrate the feasibility of the device in living tissue. We
believe that the USER device will bring value to pediatric patients, providers, and children's hospitals by
providing a solution for stent removal that reduces the use of costly OR resources, shortens surgeon
procedure time, and eliminates the risk of cognitive deficits from overexposure to anesthesia in children.
