3. HISTORY
• The first appearance of the term “stent” in the
literature originated from a new dental impression
material described by an English dentist, Charles
T. Stent.
• The use of ureteral stents in surgery was
described as early as the 19th century
• The first urologist to access the ureter
endoscopically was Dr. James Brown at Johns
Hopkins Hospital in 1893.
4. • Zimskind, however, in 1967 was the first to describe
the cystoscopic placement of indwelling ureteral stents
for obstructed ureters.
• Gibbons was the first to patent a barbed stent as a
self retaining mechanism
• T h e first “double-J” (DJ) or double pigtail stent was
developed almost simultaneously by Finney and
Hepperlen.
5. IDEAL STENT
• Easy toinsert
• Ability to relieve intraluminal and extraluminal obstruction
• H a s excellent flowcharacteristics
• Resistant to encrustation and infection
• Chemically stable after implantation in a
urinary environment.
6. Therefore stents should have
• High tensile strength
• A low friction coefficient
• Memory
• A self-retainment mechanism
• Should be both biocompatible and affordable
8. POLYETHYLENE
• First plastic polymer
Become brittle in urinary medium
Encrustation
Blockage
Fragmentation
9. POLYURETHANE
• Good tensile strength
• Can be passed overguidewire
• Does not collapse on extrinsic pressureeasily
Rigidity causes more stent related discomfort
Can damage ureter
Prone to encrustation and colonization
• Ideally should be removed within 3 months.
10. SILICON
• Silicone is the most biocompatible material
• High friction coefficient and flexibility
More difficult to navigate through a tortuous or
obstructed ureter.
Poor tensile strength
Susceptible for extrinsic compression
11. COATINGS
• HYDROGEL-
Commonly applied stent coating composed of hydrophilic
polymers that absorb water.
This added surface water reduces friction and increases
elasticity, rendering the stent easier to insert.
• PENTOSAN POLYSULFATE (PPS),
PHOSPHORYLCHOLINE (PC) COPOLYMER, AND
POLYVINYLPYRROLIDONE (PVP)
Are the newer coatings to reduce
1. Inflammation
2. Encrustation
3. Biofilm formation
12. • POLYVINYLPYRROLIDONE-IODINE (PVPI)
--PVPI complex modified polyurethane Tecoflex stents
appear to be
highly hydrophilic
Reduce encrustation
Reduce adherence of P.aeruginosa and S. aureus
14. • TRICLOSAN-ELUTING STENTS (TRIUMPH)
significantly reduced stent- related pain and urinary
symptoms
reduced symptomatic UTI
• KETOROLAC-ELUTING STENT (LEXINGTON)
developed with the goal of reducing
stent-induced pain symptoms.
15. NEWER COATINGS
• Drug-eluting and antiadhesive
under investigation
improving stent handling
reducing biofilm formation
preventing encrustation
improving patient comfort
• Silver coatings
reducing biofilm adherence without the risk of
inducing resistance
16. 3F MICROSTENT
The newly developed 3F Microstent uses a film
anchor as a proximal retaining mechanism.
Once above the obstruction, the film anchor is
deployed by retracting the integrated guidewire.
Flow characteristics of the 3F Microstent are equivalent
to those of a 4.7-Fr DJ stent.
Because a smaller-caliber stent occupies less space in
the ureter, stone passage may improve.
17. THE DUAL LUMEN STENT
It was developed with the goal of optimizing urinary
drainage.
It significantly improved the flow in an ex vivo obstructed
ureter model compared with a single 7-Fr stent and had
similar flow rates compared with two ipsilateral 7-Fr
stents.
Insertion of a dual-lumen stent has a practical
advantage over insertion of two ipsilateral stents
because it can be inserted in one pass.
18. SPIRASTENT
I t is a DJ stent with helical metalridges.
I t was designed to obtain better flow and easier stone
fragment passage by theoretically increasing the
distance between ureter wall and stent.
Although in vitro study showed promising results, the
stent appeared to allow less flow than the conventional
DJ stent
19. STENT WITH AN ANTIREFLUX VALVE
Stents equipped with an antireflux valve mechanism at
the intravesical portion of the stent demonstrate a
significant decrease in reflux rate compared with a
conventional DJ stent.
Resulting in less flank and bladder pain and thus
improved patient comfort.
20. DUAL DUROMETER
T h e hypothesis that less or softer material in the
bladder would result in fewer symptoms has
influenced stent design toward variable diameter.
Stents developed for use after endopyelotomy havea
conventional 7-Fr proximal and distal coil and a broader
body of 10 Fr.
21. TAIL STENTS OR BUOY STENTS
Developed to prevent
stent-related lower
urinary tract symptoms .
Composed of a 7-Fr or
10-Fr upper body that
tapers down to a 3-Fr
distal tail rather than a
coil.
Tail stents and buoy
stents (10 Fr to 3 Fr) are
reported to have
significantly better
drainage, reduced
bladder inflammation,
and reduced irritative
symptoms
22. MAGNETIP STENT
• T h e Magnetip stent has been developed to avoid
cystoscopic removal of the stent.
It has a metallic bead at the distal tip and can be
removed with a magnetic-tipped urethral catheter.
Studies have demonstrated up to 100% successful
retrieval in women and 75% to 97% in men.
24. ABSOLUTE AND EMERGENCY
INDICATION
• Bilateral obstruction
• Unilateral obstruction in the absence of a
functional contralateral kidney
• Ureteral obstruction with hydronephrosis andurinary
infection or sepsis.
• Intractable renal colic that cannot be controlled by
analgesia
25. RELATIVE INDICATIONS
• Stent placement before or after treatment of
urolithiasis has been a subject of controversy.
• I t is safer to place a ureteral stent incombination with
SWL for a stone larger than 1.5 to 2 cm.
26. • Stenting a ureter post-URSL is, on the other hand, still
advised if there are sizeable residual fragments,
in the presence of an anatomically or functionally
solitary kidney
if the ureter has been balloon dilated
if the patient has a UTI
if a complication such as bleeding or perforation has
occurred
27. > Routine placement of an internal stent after
uncomplicated percutaneous nephrolithotomy (PCNL)
with a low tract is not necessarily required.
> Stenting is, however, advised in the presence of
• Residual stone burden in the kidney
• Migration of residual fragments to the ureter
• Extensive edema
• Perforation of the collecting system in the presence of
persistent urinary leakageafter nephrostomy tube
removal
28. o Stents are widely used in urologic reconstructive surgery
for
• splinting the ureter.
o Stents have a dual role in this setting
the first being scaffolding the tissue to improve
organized healing
second being to allow urine to flow unhindered past
the operated field.
30. Stents are often placed prophylactically before
• Gynecologic surgery
• Urologic surgery
• Abdominal surgery
This facilitates identification of the ureter during
surgery and theoretically may reduce iatrogenic
ureteral trauma.
31. OTHER USES
• Several authors have reported on the use of stents inthe
treatment of malignant pathology of the upper
urinary tract with, BCG or Mitomycin C.
• After intravesical instillation of the agent,
vesicoureteral reflux may permit the substance to
reach the upper urinary tract.
32. • When a single ureteric stent is insufficient in relieving
benign or malignant extrinsic ureteral compression,
placing an additional ipsilateral stent has been reported
to be successful in achieving adequate kidney drainage.
• Persistent urinary extravasation after blunt renal
trauma can bet reated by ureteral stent placement with
high success rates.
33. TECHNIQUES
• Preparation — Aspirin, antiplatelet, or anticoagulation therapy
does not need to be withheld prior to stent placement.
• A urinalysis should be obtained prior to stent placement or
removal since manipulation of the stent in the setting of a
urinary tract infection can lead to bacteremia and sepsis.
• For patients with a positive urinalysis, urinary instrumentation
should be delayed, if possible, until appropriate antibiotic
treatment has sterilized the urine.
• Antibiotics — Antimicrobial prophylaxis is recommended for
all procedures involving cystourethroscopy with manipulation
including ureteral stent placement to minimize the potential for
infection.(Grade 1B)
34. Stents can be placed using various techniques including
• Retrograde placement
• Antegrade placement
• During open surgery
• Laparoscopic surgery of the urinary tract
35. > Stent placement in males
• supine position - flexible cystoscopy
• lithotomy position - rigid cystoscope
> Stent placement in females
• frog-leg position - flexible cystoscopy
• lithotomy position- rigid cystoscopy
> The distal end of the stent is positioned by advancing the
radiopaque marker under fluoroscopic guidance at the
middle of the pubic symphysis in male patients and the
lower border of the pubic symphysis in female patients.
36. COMPLICATIONS
• Ureteral Stent Symptom Questionnaire (USSQ) measures
stent-related morbidity in five categories that include
voiding symptoms, pain, work performance, sexual health,
and overall general health.
• QOL- decreased in 80%
• Work capacity –decreased in 60 %
• Sexual dysfunction-
40-80% in males
30-80 % in females.
• VUR ~ 60 %
37. COMPLICATIONS
Stent-associated symptoms can have a significant impact on
patient quality of life.
• Hematuria
• urgency
• frequency
• Dysuria
Bladder and flank pain are the most prevalent symptoms
related to indwelling ureteral stents.
Irritation of the bladder mucosa and especially the trigone by
the distal portion of the stent, reflux of urine, and smooth
muscle spasm are thought to contribute to stent-related
symptoms.
38. • Positioning the proximal coil in the upper pole of the
kidney in contrast to in the renal pelvis appears to be
better tolerated by stented patients.
• Several authors have reported that stents crossing the
midline of the bladder have a significant and deleterious
influence on associated discomfort.
• Use of alpha-blocker + anticholinergic significantly
improve SRS compared to monotherapy
39. IDEAL STENT LENGTH
> Pilcher and Patel suggested a predictive model for
ideal stent length based on patient height:
• shorter than 5 feet 10 inches 22-cm stent;
• 5 feet 10 inches to 6 feet 4 inches 24-cm stent;
• taller than 6 feet 4 inches 26-cm stent
> Straight linear measurement from PUJ to VUJ on
preoperative intravenous pyelography correlated better
with the actual ureteric length than the patient’s height
40. IDEAL STENT LENGTH
• Distance from xiphisternum to pubic symphysis
• The distance from the tip of the retrograde catheter to the
ureteropelvic junction is measured in centimeters with a
tape measure. To account for the average magnification
effect of the film, 10% of this reading is subtracted.
• Forchildren-Ideal stent length has been formulated as
“child’s age + 10” cm
• We should choose largest fitting stent available for optimal
drainage
41. STENT MIGRATION
> Despite the self-retaining design of DJ ureteral stents,
distal migration into the bladder or proximal into the
ureter is possible.
> Proximal stent migration into the ureter has been
reported to occur in 1% to 8% of patients.
> This can largely be prevented by choosing a sufficiently
long stent and having an adequate loop both in the renal
pelvis and in the bladder
> Migration of the stent into the bladder can be treated
by stent exchange.
42. UTI
> Ureteral stents are inherently subject to bacterial
colonization and therefore represent a source of UTI.
> In chronically stented patients, bacterial colonization
reaches 100%
> Indwelling time, female sex, diabetes, and chronic
kidney disease are factors influencing colonization of
ureteral stents.
43. ENCRUSTATION
> Minor encrustation on stent surfaces is often present
and usually does not result in stent blockage or
resistance at stent removal.
> More extensive and clinically significant encrustation can
be a very challenging complication and often arises
from a forgotten or retained stent.
> > 75% of stents indwelling for more than 12 weeks
44. > The duration of indwelling time of ureteral stents is the
most important risk factor for development of
encrustation.
> Additional risk factors for stent encrustation
include pregnancy (change 4-6 weekly), UTI or
urosepsis, history of stone disease,metabolic
or congenital abnormalities.
> Calcium oxalate appears to be the major
component of stent encrustation in the
absence of UTI, pH values below 5.5, and
hyperuricosuria.
45. FORGOTTEN STENTS
• T h e forgotten or neglected stent is amultifactorial problem that
originates from both poor patient compliance and health
system issues related to patient follow-up.
• How to prevent it??
Patient education
Reminder mechanisms:
• Log books
• Card
• Web-based registries
• Computerized logs
• Software that arranges stent change or removal and
sends reminder e-mails to patient and physician.
46. FECal stents
• Classification: Acosta-Miranda et al.
• Grade I: minimal linear encrustations along bladder portion of
the pigtail of the indwelling ureteral stent
• Grade II: minimal linear encrustations along kidney portion of
the pigtail of the indwelling ureteral stent
• Grade III: circular encrustation completely encasing either of
the pigtail portions as well as linear encrustation of the ureteral
aspects of the indwelling ureteral stent
• Grade IV: circular encrustations completely encasing both of
the pigtail portions of the indwelling ureteral stent
• Grade V: diffuse and bulky encrustations completely encasing
both of the pigtail and ureteral portions of the indwelling
ureteral stent.
47.
48. TREATMENT
• Based on FECal classification
• Grade I encrusted stents- can be removed with
cystoscopy or with cystolithotripsy of the distal part only.
• Grade II-proximally encrusted stents can be removed
after ESWL on this part.
• Grades III, IV and V encrusted stents usually require
combined endourological interventions, including URS,
RIRS (retrograd intrarenal surgery) and PCNL.
• Rarely, open or laparoscopic surgery is needed for
removal of the heavily encrusted DJSs.
51. HISTORY
• Thomas Hillier reported on the first PCN for the
drainage of a hydronephrotic kidney in a 4-year old boy
in 1865.
• Fernström’s report on the first percutaneous stone
extraction in 1976 initiated the PCNL era.
52. INDICATIONS
> Acute or chronic upper urinary tract obstruction in
which access to the kidney is impossible from the
lower urinary tract because of stones, infections,
tumours, or anatomic anomalies.
> Patient's creatinine level is rising above the reference
range and the urine cannot be drained through the
ureter.
> Renal pelvis disorders (UPJ obstruction, ureter duplex,
ureter fissures, double renal collecting systems)
> Hydronephrosis in renal transplant allografts
53. MATERIALS
• Similar to ureteral stents
• A n ideal nephrostomy tubeis
Biocompatible
Has excellent flow characteristics
Is easy to insert
Resists Infection, encrustation, and
dislodgement
And does not induce symptoms
54. COUNCILMAN CATHETER
• This is a modified Foleys catheter, with a end hole.
> This type of nephrostomy drainage is useful if the
nephrostomy tube requires frequent changes.
55. KAYE’S BALLOON TAMPONADE
> Originally the catheter
was designed to arrest
post-PCNL bleeding.
> The tamponade is
provided by the balloon
and the
central channel provides
drainage.
57. FOLEY CATHETER
> These are used for
long term drainage.
> Those patients which
require
repeat tube changes.
> Disadvantage is,
it is not
radiopaque.
58. MALECOTS CATHETER
> These catheters have a
flower at the end of
catheter as self-
retaining mechanism.
> They tend to fall out with
firm pull.
> Not widely used as
urethral catheters,
> Mainly used as
nephrostomy catheter.
59. CIRCLE NEPHROSTOMY TUBES
> Less mucosal irritation when compared with foley
catheters.
> It remained in the same position in the renal pelvis
> Better drainage of the renal pelvis and calyces
when compared with a foley catheter
> It was useful to irrigate the renal pelvis
> Easier to change in the office without requiring
fluoroscopic guidance
> It would not slide out if adequately secured.
60.
61. RE-ENTRY CATHETERS
• Re-entry catheters are
designed to permit
nephrostomy drainage
while ensuring access
to the ureter, should
this be necessary.
62. ADVANTAGES
> Placement and exchange of the tube under local
anesthesia.
> Nephrostomy tube offers better flow characteristics.
> In contrast to a DJ stent, the external drainage
nephrostomy tube can be easily unblocked by gentle
irrigation in the event of blockage.
> Toadminister therapeutic drugs to the upper urinary
tract. BCG or mitomycin C
> ?Chemolytic agents to achieve stone dissolution
> Toobtain a nephrostogram
