Types and characteristics of guide wires and ureteric stents used in urology

3. A device used to enter tight spaces, e.g.,
obstructed valves or channels, within the body, or
to assist in inserting, positioning, and moving a
catheter. Guide wires vary in size, length,
stiffness, composition, and shape of the tip

4. The development of guidewires in urology began
with the application of angiographic tools in urologic
endoscopy. Angiographic guidewires reported to be
used in 7 patients with ureteral obstruction in 1981 .
The authors noted in this study that their methods
allow the “placement of angiographic guide wires
and catheters past ureteral obstacles when
standard urological retrograde procedures are not
feasible technically.”

5. The transvesical approach was described as where
a 6Fr open-ended polyethylene catheter was placed
at the ureterovesical junction and followed by
advancing a 0.035 in. diameter guide wire.
The authors noted several advantages of the
angiographic catheters and wires that allowed their
urological application

6. Today, guide wires are developed for specific
specialities and specific situations. Each one is
designed and manufactured with different
characteristics. In fact, the basic concepts of guide
wire technology actually cover 15 broad areas:
• flexibility
• torqueability (control of the distal tip of the wire by rotation of
the proximal tip)
• crossability (ability to navigate past obstructions),

7. • supportability (ability to support another device over it),
• core diameter
• tip style
• shaping ribbons
• tip coils
• coatings
• support
• tip load
• support catheters
• wire length

8. - Materials from which wires are made varies.
- Core : Nitinol (nickel-titanium alloy) or steel is
usually the main core in most wires.
- Coat : Some guide wires are coated with other
substances such as silicone or
polytetrafluoroethylene (PTFE) which enhance
lubricity, or with other novel hydrophilic coatings
to allow for easier manoeuvrability in tortuous
lumens

9. - Tips : The tips of these wires are generally
“floppy” for 1 to 3 cm.
Bentson and Newton wire designs have flexible
tips of up to 15 cm and are seldom used today.
Some wires have a movable core that can
be partially withdrawn to increase
length of the flexible tip.
- The distal tip can be straight, angled, or “J”
tipped.
- Rigidity : of the wires can be varied by
changing the diameter and design of the
inner core wire

11. - Diameter : ranges from 0.018 to 0.038
inches, the most commonly used being 0.038
inches.
- Length : vary from 80 to 260 cm. The most
useful length for endourology is
145 cm.

12. - Establishment of percutaneous or ureteroscopic
acces
- straightening of the ureter
- A guide for dilation of the ureter or percutaneous
tract, and stent placement.
- allow a catheter to be
advanced along it .

13. - The most common design is a solid stainless steel
core around which an outer wire is wrapped.
- Nitinol (nickel-titanium) can be used for inner core
construction, and this gives guidewires a kink-
resistant, slightly stiffer property. Some newer wires
(Zebra wire; Boston Scientific, Natick, MA, and
Roadrunner wire, Cook Urological, Spencer, IN)
have a nitinol core wire and polyurethane outer
layer

14. - These wires are well suited for passage of the
ureteroscope as there is less friction of the
ureteroscope over the polyurethane, and the stiffer
core allows more reliable transmission of the
“push” from the urologist to the tip of the
ureteroscope.

15. - When the outer polyurethane layer is coated with a
hydro-philic polymer, these wires become
exceptionally slippery. These “glide wires” are
incredibly adept at negotiating around impacted
ureteral calculi, tortuous ureters, and ureteral
strictures.
- A new hybrid designed wire (Sensor; Boston
Scientific, Natick, MA) incorporating a hydrophilic
tip with a polytetrafluoroethylene (PTFE)-coated
shaft may serve as both an access and safety wire
for difficult access cases.

16. Amplatz Super Stiff™ Guidewire
is a stainless steel wire with a
flat-wire coil and PTFE coating.
It is available in a variety of
diameters and tip configurations
& designed so we can straighten
tortuous anatomies and deliver
heavier instruments

17. Sensor PTFE-Nitinol Guidewire
with Hydrophilic Tip
A new hybrid designed wire
incorporating
a hydrophilic tip
with a polytetrafluoroethylene
(PTFE)-coated shaft
may serve as both an access
and safety wire for difficult
access cases

19. Zebra™Guidewire
Distinct Construction
Kink-resistant nitinol core
Flexible PTFE "jacket" designed for
torqueability
Enhanced Visualization
Blue and white striped pattern is
designed to provide clear endoscopic
visualization of wire movement
Platinum distal tip is visible under
fluoroscopy to aid in confirmation of
guidewire position
Lubricious Coating
Uro-Glide™ Coating on distal 60cm
designed to reduce surface friction for
smooth entry, advancement and
withdrawal with precise proximal
handling

21. Roadrunner
Hydrophilic Wire Guide
Used to gain ureteral
access, to establish a tract,
and to assist in the
placement, replacement,
and exchange of medical
devices during urological
procedures. May also be
used for catheter
positioning and exchange in
a tortuous or kinked ureter,
traversing a stone en route
to the kidney,

22. BiWire
Nitinol Core Wire Guide
Used to gain ureteral
access, to establish a
tract, and to assist in the
placement, replacement,
and exchange of medical
devices during
urological procedures.
The BiWire has flexible
tips at both ends—a
straight tip on one end
and an angled tip at the
other.

23. Fixed Core Guide wire
j tip
& straight tip

24. - The choice of the most appropriate wire depends
on the present task, the patient’s anatomy, and
upper urinary tract problem being confronted.
- Despite all of these advances in wire design and
construction, a 0.038-inch–diameter straight,
flexible-tip, Teflon-coated stainless steel wire is still
an excellent choice for most cases.

25. - Fragmentation.
- Bleeding and mucosal injury
- Perforation of urinary tract
- Knotting

26. URETERIC CATHETER
Material
The material is polyethylene with
radiopaque coating
Markings—Single marking at every
centimeter. The marking is as follows:

27. 5 cm—single mark
10 cm—two marks
15 cm—3 marks
20 cm—4 marks
25–5 marks
30—one bold mark
35–2 marks
40–3 marks
45–4 marks
50–5 marks
No marking beyond 50 cm. The length
generally is 70 cm.

28. 
The ureteric catheters are classified
depending on the tip configuration:
1. Open end catheter
Single opening at the tip, no side
openings. It is used for drainage and
performing pyelography. It can be
passed over glidewire across obstruction or
kink.

31. 3. Cone tipped ureteric catheter
: Available in different sizes. The
size is described as the size of tip
and the catheter. The tip is pointed
and a hole just proximal to the tip
Used for bulb retrograde pyelogram
.

33. 9. Double lumen ureteric catheter: It is 10 Fr in
size and has
two channels one opening at the tip and one on
the side . The openings are approximately 1 cm
apart. This is used for passing
additional safety catheter or performing a contrast
study without removing
the preplaced wire. It is 50 cm long.
A variant in the form of flexitip is also available.
This catheter eliminates the
need for multiple catheterization. The flexitip is
intended for a traumatic
catheterization into the ureter

35. 7. Pig tail ureteric catheter

: Available as 70 cm and 90 cm. It has a
single curl at
the kidney end. This can be kept as self-
retaining ureteric catheter.

36. Double J (DJ) stent can be classified on basis of:
1. Length.
2. Size.
3. Material.
4. Miscellaneous.
1. Classification on basis of length: Length of
stent is the straight part of stent
and not from tip to tip.
For tortuous ureter larger length is necessary.
Generally length are variable
between 12 cm and 30 cm

38. Different ways to measure length of DJ are:
a. Formula for deciding the length of the stent
– Pediatric age group: Age +10 (in cm)
– Adults: Height from 149.5 cm to 178.5 cm—
DJ length of 22–26 cm
b. On plain X-ray KUB (of actual size) length of
DJ required is equal to length
measured from xiphisternum to pubic
symphysis.
c. In an IVP plate (of actual size) length of the
DJ required is equal to distance
between VUJ and PUJ.

39. 2. Classification on basis of size: Size is
measured at the shaft and represents at
the outer diameter of stent. It generally varies
from 3 Fr to 8 Fr.
3. Classification on basis of material used.
1. Polymers:
– Polyurethane
– Silicone
– C Flex – (Cook urological)
– Sof- flex (Cook urological)
– Percuflex (Boston Scientific)
2. Metallic (Resonance, memocath)

41. A. Polyurethane stents: It has good tensile
strength and can be passed over
guidewire and does not collapse on extrinsic
pressure easily. Rigidity causes
more stent related discomfort and can damage
ureter. More prone to
encrustation and colonization, should not be
left for more than 6 months
ideally should be removed within 3 months.

42. B. Silicone stent: it has poor
tensile strength and susceptible for extrinsic
compression. Poor strength
requires low inner diameter to outer diameter
ratio which leads to smaller
lumen. It has poor drainage efficiency as
compared to polyurethane. The
poor coil retention leads to spontaneous
migration.

43. C. Percuflex,
less bladder irritation. More biocompatible and
can be left for longer
time. These have higher inner diameter/outer
diameter ratio and hence
have bigger lumen. This property is permitted
by these copolymers with
higher strengths. These stents have hydrophilic
polymer coating for smooth
surface and easy insertion

44. D. Metallic stent: It is made of special metallic
material, unlike other stent it is not hollow and
is solid cylindrical stent.
Preferably used for extrinsic compression of
ureter. Resistant to encrustation
can be left for 12 months.

45. Miscellaneous Stents
A. Dangler stents18 are usual DJ with
additional nylon or prolene wire loops
dangling out of the stent end. This helps in its
removal without cystoscopy.

46. B. Endopyelotomy stent :
Used after endopyelotomy or
endourological management of upper ureteric
stricture or PUJ obstruction,
to maintain the lumen of the upper ureter and
PUJ. Proximal end is wide
with narrow distal end like usual stent.