A medical stent is sized for placement in a ureter. The stent includes a first section which includes a first material, defines a lumen, and includes a first coil completing at least one revolution. A second section of the stent includes a second material, defines a lumen, and includes a second coil completing at least one revolution. A third section defines a lumen and is located between the first and second sections. The third section includes a co-extrusion of the first and second materials. One of the first or second sections is harder than the other section.
1. A medical stent comprising:
a proximal end portion defining a lumen and including a first retention structure, the proximal end portion constructed from at least a first material having a first durometer value, the first retention structure includes a coil offset from a longitudinal axis of the medical stent, the proximal end portion defining a first opening and a second opening, the first opening and the second opening being in fluid communication with the lumen defined by the proximal end portion;
a suture extending through the first opening and the second opening and being configured to facilitate the removal of the medical stent from a body of a patient;
a distal end portion defining a lumen and including a second retention structure, the distal end portion constructed from at least a second material having a second durometer value, the second durometer value being greater than the first durometer value; and
a central portion disposed between the proximal end portion and the distal end portion, the central portion defining a lumen in fluid communication with the lumen of the proximal end portion and the lumen of the distal end portion, the lumen of the central portion defining a longitudinal axis, the central portion constructed from the first material and the second material, the first material and the second material being co-extruded within the central portion such that the first material and the second material are distinct from each other and arranged substantially asymmetrically within a plane normal to the longitudinal axis.
2. The medical stent of claim 1 , wherein the relative amounts of the first material and the second material within the central portion vary non-linearly within a plane parallel to the longitudinal axis.
3. The medical stent of claim 1 , wherein an outer surface of the central portion smoothly transitions to an outer surface of the proximal end portion and an outer surface of the distal end portion.
4. The medical stent of claim 1 , wherein an inner diameter of the central portion, an inner diameter of the proximal end portion adjacent the central portion and an inner diameter of the distal end portion adjacent the central portion are substantially constant.
5. The medical stent of claim 1 , wherein the proximal end portion is devoid of the second material and the distal end portion is devoid of the first material.
6. The medical stent of claim 1 , wherein the first material includes ethylene vinyl acetate.
7. The medical stent of claim 1 , wherein the first material has a durometer value of about 70 to about 90 on a Shore A scale.
8. The medical stent of claim 1 , wherein at least one of the proximal end portion, the distal end portion, and the central portion includes a lubricant.
9. The medical stent of claim 8 , wherein the lubricant is a hydrophilic material.
10. The medical stent of claim 8 , wherein the lubricant is disposed about an outer surface of the proximal end portion and an outer surface of the distal end portion.
11. The medical stent of claim 8 , wherein the lubricant is covers at least a portion of each of the proximal end portion, the distal end portion, and the central portion.
12. The medical stent of claim 8 , wherein the lubricant covers the entire medical stent.
13. The medical stent of claim 1 , wherein a proximal end of the first retention structure extends in a direction parallel to longitudinal axis defined by the medical stent.