Ureteral StentsUreteral StentsFor the Diagnostic RadiologistFor the Diagnostic Radiologist

Jud Gash, MDJud Gash, MD University of Tennessee, KnoxvilleUniversity of Tennessee, Knoxville

The Typical StentThe Typical Stent

IndicationsIndications PlacementPlacement StentStent Normal PositionNormal Position Common SymptomsCommon Symptoms

IndicationsIndications

Benign or Malignant obstruction reliefBenign or Malignant obstruction relief Adjunct to stone therapyAdjunct to stone therapy

ObstructionObstruction ESWLESWL

PerioperativePerioperative Identification of the ureterIdentification of the ureter

Management of Urine leaksManagement of Urine leaks After trauma, surgery or fistulaAfter trauma, surgery or fistula

PlacementPlacement

Typically in ORTypically in OR Cystoscopy (identify ureteral orifice)Cystoscopy (identify ureteral orifice) +/- Retrograde pyelogram to outline upper tract+/- Retrograde pyelogram to outline upper tract Placement of soft guidewire into upper tract Placement of soft guidewire into upper tract

(kidney)(kidney) Place stent over guidewire (using pusher)Place stent over guidewire (using pusher) Remove guidwireRemove guidwire

Stent PlacementStent Placement

Typical StentTypical Stent

Double J/Pigtail configurationDouble J/Pigtail configuration 5-9 Fr5-9 Fr 20-32 cm20-32 cm PolyurethanePolyurethane

An aside – French Scale for DradsAn aside – French Scale for Drads Charriere, Parisian surgical Charriere, Parisian surgical

instrument makerinstrument maker French scale or gauge systemFrench scale or gauge system

Fr, F or GaFr, F or Ga Catheter sizeCatheter size

Sp. = External diameterSp. = External diameter 1 Fr = 1/3mm1 Fr = 1/3mm

D(mm) = Fr/3D(mm) = Fr/3 Ex. 30 fr catheter is (30/3) Ex. 30 fr catheter is (30/3)

– 10mm in diameter– 10mm in diameter Fr is close to circumferenceFr is close to circumference

30 fr cath is about 30mm in 30 fr cath is about 30mm in circumferencecircumference

pi*d = Cpi*d = C Contrasts Needle gauge size, Contrasts Needle gauge size,

where increasing gauge is where increasing gauge is smallersmaller

Normal PositionNormal Position Proximal coil in renal Proximal coil in renal

pelvispelvis Distal coil in bladder Distal coil in bladder

In upper 1/4In upper 1/4 Within 5cm of UVJWithin 5cm of UVJ Not beyond midline or Not beyond midline or

along bladder basealong bladder base Proper position …Proper position …

Assures proper functionAssures proper function Reduces chance of Reduces chance of

migrationmigration Reduces irritative Reduces irritative

symptomssymptoms

Proximal loop in renal pelvis

Distal loop in bladder, best in

upper 1/4

Common SymptomsCommon Symptoms

Stent IrritationStent Irritation Flank discomfortFlank discomfort Bladder discomfortBladder discomfort

PainPain Desire to voidDesire to void IncontinenceIncontinence

Hematuria/PyuriaHematuria/Pyuria Vesicoureteral RefluxVesicoureteral Reflux

Complications/IssuesComplications/Issues

Malposition (Too short or long/outside ureter)Malposition (Too short or long/outside ureter) MigrationMigration UTIUTI Inadequate Relief of ObstructionInadequate Relief of Obstruction EncrustationEncrustation FractureFracture Ureteral erosion/fistulaUreteral erosion/fistula Forgotten StentForgotten Stent

MalpositionMalposition Too shortToo short

Doesn’Doesn’t bridge the t bridge the obstruction/ureterobstruction/ureter

““fish reeling”fish reeling” Too longToo long

IrritationIrritation Urinary tract penetrationUrinary tract penetration

Usually proximalUsually proximal Urinoma; hematomaUrinoma; hematoma

Stent in optimal position

Malposition - Too Short Malposition - Too Short

Malposition – Too LongMalposition – Too Long

Update – Multi Length StentsUpdate – Multi Length Stents Variable length Variable length

22-28 cm most 22-28 cm most commoncommon

Distal coil adjusts to Distal coil adjusts to ureter lengthureter length Shorter ureter – more Shorter ureter – more

coilcoil Longer ureter – less Longer ureter – less

coilcoil Many fewer Many fewer “too “too

short” or “too long” short” or “too long” stentsstents

MalpositionMalposition

Proximal stent outside kidney

Subtle indication of malposition with stent distant to ureteral stone (after reposition)

MigrationMigration

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

MigrationMigration

Distal (more common) and proximal migration

Urinary Tract InfectionUrinary Tract Infection

Not uncommon with stentNot uncommon with stent CausesCauses

Stent placement (Abx before placement)Stent placement (Abx before placement) ColonizationColonization

Urinary tract infectionUrinary tract infection

Patient with flank pain and fever 1 week following stent for distal stone

Inadequate Relief of Obstruction Inadequate Relief of Obstruction or Stent Malfunctionor Stent Malfunction

Relief of obstruction with ureteral stent is Relief of obstruction with ureteral stent is complexcomplex Intrinsic obstruction (ie stones - stent good)Intrinsic obstruction (ie stones - stent good) Extrinsic obstruction (ie malignant – less effective)Extrinsic obstruction (ie malignant – less effective)

Complex issuesComplex issues

Stent May become clogged/obstructedStent May become clogged/obstructed Clinical SuggestionClinical Suggestion

Flank pain (but often present anyway)Flank pain (but often present anyway) Renal insufficiency (insenstive)Renal insufficiency (insenstive) Hydronephrosis (may persist from previous)Hydronephrosis (may persist from previous)

Inadequate Relief of Obstruction Inadequate Relief of Obstruction or Stent Malfunctionor Stent Malfunction

Imaging DiagnosisImaging Diagnosis Doppler US – no ureteral jet and increasing hydroDoppler US – no ureteral jet and increasing hydro No reflux at VCUG (or loopagram)No reflux at VCUG (or loopagram)

Patent StentPatent Stent

Stent Obstruction with exchangeStent Obstruction with exchange

EncrustationEncrustation

All stents will accrue crystalline depositionAll stents will accrue crystalline deposition Hastened by UTI; lithogenic urineHastened by UTI; lithogenic urine Increases with time (50% at 6-12 weeks)Increases with time (50% at 6-12 weeks)

A main reason for stent exchangeA main reason for stent exchange

Particularly involves proximal and distal endsParticularly involves proximal and distal ends ComplicationsComplications

Urinary tract injury and stent fracture at removalUrinary tract injury and stent fracture at removal Must be dealt with if severe prior to removalMust be dealt with if severe prior to removal

Lithotripsy, cystoscopy, etc.Lithotripsy, cystoscopy, etc.

EncrustationEncrustation

EncrustationEncrustation

EncrustationEncrustation

EncrustationEncrustation

Stone analysis revealed calcium oxalate 8% and calcium phosphate 92%

Kidney International (2007) 72, 899–900. doi:10.1038/sj.ki.5002429

Ureteral Erosion or FistulaUreteral Erosion or Fistula

Rarest and most feared Rarest and most feared complication, especially complication, especially arterialarterial

Usually in setting of Usually in setting of XRT and malignancy, XRT and malignancy, with indwelling stent with indwelling stent eroding into vesseleroding into vessel

Hematuria, can be Hematuria, can be massivemassive

Arteriogram or CTAArteriogram or CTA

Stent FractureStent Fracture

Urine is a hostile enviromentUrine is a hostile enviroment Rare todayRare today

Increases with indwelling timeIncreases with indwelling time Increases with encrustationIncreases with encrustation

Stent FractureStent Fracture

Forgotten StentForgotten Stent

Forgotten StentForgotten Stent

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

Ureteral Stents – Wrap upUreteral Stents – Wrap up Typical StentTypical Stent

IndicationsIndications PlacementPlacement StentStent Normal PositionNormal Position Common SymptomsCommon Symptoms

ComplicationsComplications Malposition (Too short or long/outside ureter)Malposition (Too short or long/outside ureter) MigrationMigration UTIUTI Inadequate relief or recurrent obstructionInadequate relief or recurrent obstruction EncrustationEncrustation FractureFracture Ureteral erosion/fistulaUreteral erosion/fistula Forgotten StentForgotten Stent