1. Ureteral Stents
For the Diagnostic Radiologist
Jud Gash, MD
University of Tennessee, Knoxville
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3. The Typical Stent
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Indications
Placement
Stent
Normal Position
Common Symptoms

4. Indications
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Benign or Malignant obstruction relief
Adjunct to stone therapy
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Perioperative
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Obstruction
ESWL
Identification of the ureter
Management of Urine leaks
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After trauma, surgery or fistula

5. Placement
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Typically in OR
Cystoscopy (identify ureteral orifice)
+/- Retrograde pyelogram to outline upper tract
Placement of soft guidewire into upper tract
(kidney)
Place stent over guidewire (using pusher)
Remove guidwire

6. Stent Placement

7. Typical Stent
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Double J/Pigtail configuration
5-9 Fr
20-32 cm
Polyurethane

8. An aside – French Scale for Drads
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Charriere, Parisian surgical
instrument maker
French scale or gauge system
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Fr, F or Ga
Catheter size
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1 Fr = 1/3mm
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D(mm) = Fr/3
Ex. 30 fr catheter is (30/3)
– 10mm in diameter
Fr is close to circumference
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Sp. = External diameter
30 fr cath is about 30mm in
circumference
pi*d = C
Contrasts Needle gauge size,
where increasing gauge is
smaller

9. Normal Position
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Proximal coil in renal
pelvis
Distal coil in bladder
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In upper 1/4
Within 5cm of UVJ
Not beyond midline or
along bladder base
Proper position …
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Assures proper function
Reduces chance of
migration
Reduces irritative
symptoms
Proximal loop in
renal pelvis
Distal loop in
bladder, best in
upper 1/4

10. Common Symptoms
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Stent Irritation
Flank discomfort
 Bladder discomfort
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Pain
 Desire to void
 Incontinence
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Hematuria/Pyuria
Vesicoureteral Reflux

11. Complications/Issues
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Malposition (Too short or long/outside ureter)
Migration
UTI
Inadequate Relief of Obstruction
Encrustation
Fracture
Ureteral erosion/fistula
Forgotten Stent

12. Malposition
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Too short
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Doesn’t bridge the
obstruction/ureter
“fish reeling”
Too long
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Irritation
Urinary tract penetration
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Usually proximal
Urinoma; hematoma
Stent in optimal position

13. Malposition - Too Short

14. Malposition – Too Long

15. Update – Multi Length Stents
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Variable length
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Distal coil adjusts to
ureter length
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22-28 cm most
common
Shorter ureter – more
coil
Longer ureter – less
coil
Many fewer “too
short” or “too long”
stents

16. Malposition
Proximal
stent outside
kidney
Subtle indication of malposition with stent
distant to ureteral stone (after reposition)

17. Migration
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Prevented by proximal and distal “J” or loop
May occur due to peristalsis or short stent

18. Migration
Distal (more common)
and proximal migration

19. Urinary Tract Infection
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Not uncommon with stent
Causes
Stent placement (Abx before placement)
 Colonization
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20. Urinary tract infection
Patient with flank pain and fever 1
week following stent for distal stone

21. Inadequate Relief of Obstruction
or Stent Malfunction
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Relief of obstruction with ureteral stent is
complex
Intrinsic obstruction (ie stones - stent good)
 Extrinsic obstruction (ie malignant – less effective)
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Complex issues
Stent May become clogged/obstructed
Clinical Suggestion
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Flank pain (but often present anyway)
Renal insufficiency (insenstive)
Hydronephrosis (may persist from previous)

22. Inadequate Relief of Obstruction
or Stent Malfunction
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Imaging Diagnosis
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Doppler US – no ureteral jet and increasing hydro
No reflux at VCUG (or loopagram)

23. Patent Stent

24. Stent Obstruction with exchange

25. Encrustation
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All stents will accrue crystalline deposition
Hastened by UTI; lithogenic urine
 Increases with time (50% at 6-12 weeks)
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Particularly involves proximal and distal ends
Complications
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A main reason for stent exchange
Urinary tract injury and stent fracture at removal
Must be dealt with if severe prior to removal
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Lithotripsy, cystoscopy, etc.

26. Encrustation

27. Encrustation

28. Encrustation

29. Encrustation
Stone analysis revealed calcium oxalate 8% and calcium phosphate 92%
Kidney International (2007) 72, 899–900. doi:10.1038/sj.ki.5002429

30. Ureteral Erosion or Fistula
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Rarest and most feared
complication, especially
arterial
Usually in setting of
XRT and malignancy,
with indwelling stent
eroding into vessel
Hematuria, can be
massive
Arteriogram or CTA

31. Stent Fracture
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Urine is a hostile enviroment
Rare today
Increases with indwelling time
 Increases with encrustation
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32. Stent Fracture

33. Forgotten Stent

34. Forgotten Stent
IJCRI 201 2;3(4):45–47.
www.ijcasereportsandimages.com

35. Ureteral Stents – Wrap up
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Typical Stent
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Indications
Placement
Stent
Normal Position
Common Symptoms
Complications
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Malposition (Too short or long/outside ureter)
Migration
UTI
Inadequate relief or recurrent obstruction
Encrustation
Fracture
Ureteral erosion/fistula
Forgotten Stent