Background

The current gold standard for a ureteral stent is a double-J stent made from a polymeric material. The stent is comprised of a curl at the proximal end of the stent, located in the kidney, and distal end of the stent, located in the bladder. A hydrophilic coating is typically added to the stent to decrease friction, resulting in a smoother insertion. The gold standard ureteral stent contains small holes in the walls of the stent which promote the flow of urine. The  double-J stent is inserted via cystoscopy. Markings on the stent are visualized from outside the body when using the cystoscope to determine how deep the stent has been placed, but in most cases fluoroscopy is used to ensure the correct placement of the stent. When inserting the stent a 0.035” sensor tip guidewire is moved through the bladder and ureter into the kidney while being monitored via fluoroscopy. Once the guidewire is placed, the stent is advanced over the guidewire into the renal pelvis using a stent pusher. When the renal pelvis is reached, the guidewire is carefully withdrawn forming the curl in the proximal end of the stent. A majority of stents are removed via flexible cystoscopy removal. Flexible cystoscopy removal, the more common of the two methods, is used for the removal of all long term stents and some short term stents. During this procedure, a tube containing a visual scope is passed through the urethra and into the bladder where the distal curl dwells. After the tube is successfully inserted, small forceps are inserted through the tube and the distal curl of the stent is grasped and pulled out slowly along with the scope.

There is a large unmet medical need for ureteral stents that reduces complications caused by the gold standard. The first issue with the gold standard is grab ease and access to the stent upon removal. If the stent lies in the bladder upon removal, cystoscopy, endoscopy of the urinary bladder via the urethra, can be used. On the other hand, if the stent retrieves into the ureter due to reflux of urine, an outpatient procedure where a scope passes through the bladder and urethra and into the ureter known as ureteroscopy must be endured. Ureteroscopy should be avoided because the ureter is a difficult area for a surgeon to access due to the sheer size of the ureter, only a 3-4 mm opening. Another key issue with the current gold standard is stent longevity.  This is due to the formation of calcium deposits on the distal J curl which in turn causes adverse events such as discomfort, the frequency to urinate, pain during urination and bloody urine. Grade 3 and grade 4 adverse events may require the stent to be removed prior to the designated time allotment, allowing only short-term use of the ureteral stent.

Summary:

The Fornax ureteral stent and retrieval tool are designed to treat obstruction of urine flow from the kidney to the bladder. Current ureteral stents cause adverse events including, but not limited to, bladder discomfort, increased frequency to urinate, pain during urination, and bloody urine due to calcification of the J-curl in the bladder over time.  Removing the distal J-curl of a ureteral stent and replacing it with electromagnetic technology eliminates material residing in the bladder, eradicates the need for ureteroscopy, increases stent longevity and provides optimal comfort for long-term use. In turn, the new design elicits a decrease in hospital visits due to a decrease in adverse events, reducing patient spending and increasing quality of life respectively. With chronic and acute unilateral ureteral blockages affecting 5 out of every 1,000 and 1 out of every 1,000 individuals respectively, the re-designed ureteral stent and retrieval tool will revolutionize urological care. 

Benefits:

• A reduction in the possibility of an infection compared to conventional stents
• Allows for an accurate removal of stent through noninvasive method
• Less discomfort in patients than traditional stents

Applications:

• Serves as a device to keep the urine pathway open when the ureter is blocked or damaged. 

Relevant KeyWords:

• Stent
• Ureter
• Magnetics 

References

“Ureteral Stents Market Size, Share: Industry Analysis Growth.” Allied Market Research, www.alliedmarketresearch.com/ureteral-stents-market.