Surgical Treatment of Renal and
Ureteral Stones
Herb Wiser
Treatment Modalities
•
•
•
•
ESWL (extracorporeal shock wave lithotripsy)
Ureteroscopy
PCNL (percutaneous nephrolithotomy)
Open or laparoscopic surgery
– Ureterolithotomy
– Anatrophic nephrolithtomy
ESWL
•
•
•
•
“Bath tub” treatment
Shock waves to break stones
Non-invasive
Results worse for
Bigger stones
Stones located in the lower pole of the kidney
Hard stones
Electrohydrolic
(Spark gap)
Energy
Sources and
Configurations
Electromagnetic
Piezoelectric
Mechanism of Action –
Electrohydraulic
• Power source at F1
• Generated in water medium
• Contained in a ellipsoid shield
• Waves (energy) concentrated at F2
Prognostic factors for ESWL success
Wang LJ et al. Eur Urol 2005
• <900 HU (72% success) vs >900 (35%)
• Size <12mm (78%) vs >12 (26%)
• Non-Lower pole (70%) vs Lower pole (46%)
Pareek G et al. Urology 2005
• 24/29 pts (83%) with SSD <10cm were stone free
• 6/35 pts (17%) with SSD >10cm were stone free
Success Rates ESWL
• Renal - 55-75% (lowest for lower pole stones)
• Proximal Ureter
– <1cm – 90%
– >1cm – 70%
• Mid/Distal Ureter
– <1cm – 85%
– >1cm – 75%
Contraindications to ESWL
•
•
•
•
•
Pregnancy
Coagulopathy
UTI
Intrarenal vascular calcifications
Renal artery aneurysm or AAA
Complications of ESWL
• Retroperitoneal Hematoma
– >25% incidence on imaging
– <0.5% clinically significant
Complications of ESWL
Complications of ESWL
• Pain from stone fragment passage
– 25-50% of pts
• Steinstrasse
– ~5% of pts
http://radiologyinthai.blogspot.co
m/2010_12_01_archive.html
Complications of ESWL
• ? Long term effects of ESWL
– DM and HTN
– Retrospective studies show increased incidence of
DM and HTN in stone formers
– Is this because a stone formers have worse dietary
habits?
– Prospective trials show no increase in DM/HTN,
but follow up is limited (a few years)
Ureteroscopy
•
•
•
•
•
Placing small scope into ureter or kidney
Flexible or rigid scopes
Remove the stone (‘basket’, ‘loop’, ‘snare’)
Break the stone - Laser
May leave a stent (surgeon’s discretion)
Uretero
scopes
Flexible Ureteroscopy
Grasso M. Arch Esp Urol 2008.
http://www.windsorurology.co.uk/
Image Quality
Laser Lithotripsy
Laser Lithotripsy
Stone Basketing
Ureteroscope Considerations
• Flexible Scope outer sizes 8.5-10 Fr
– Working channel 3.5Fr
• Semirigid Scope @ tip 7-9 Fr
proximally 6-13.5 Fr
one is 4.5/6.5 Fr
– Working channel up to 3-6 Fr
Laser Lithotripsy
• Holmium:YAG laser is most common type
for laser lithotripsy
– Erbium:YAG and Thulium lasers under
development, potentially superior to Ho:YAG,
not widespread
– Very limited depth of penetration (0.4mm)
• Limits tissue damage
– Highly effective at lithotripsy
Success Rates Ureteroscopy – Old Data
• Renal - ~70-80% (lowest for lower pole stones)
– Stone clearance decreases with increasing stone
size
• Proximal Ureter - ~80%
• Mid Ureter – 80-90%
• Distal Ureter - ~95%
Complications of URS
• Ureteral Perforation
– ~5%
– Treatment is stenting (~6 weeks)
– Can result in stricture in the long term (1% of all
URS)
• Ureteral Stricture
– Could be due to stone or URS
• Ureteral Avulsion
– Rare but really, really bad
Stents
•
•
•
•
•
Polymer tubes from kidney to bladder
Keep the ureter open
Dilates the ureter
Patient removal vs surgeon removal
Symptoms
– Bladder spasms
– Flank pain
– hematuria
Stents
People generally HATE them, but they are a
necessary evil.
Percutaneous Approach
•
•
•
•
Big stones (>2cm)
Stones likely to be struvite
Difficult anatomy (calyceal diverticulum, etc)
ESWL failures
PCNL
http://www.actasurologicas.info
Lithotripsy for PCNL
• Ultrasonic Lithotriptor
• Pneumatic Lithotriptor
• Laser (Ho:YAG)
Ultrasonic Lithotriptor
•
•
•
•
•
•
•
•
Electric current stimulates piezoelectric crystal
Crystals expand and contract
Creates vibrations at ~25,000 Hz
Transmitted to tip of probe
“Drills” the stone
Strictly mechanical energy
No heat, cavitation or shock waves
Suctions fragments through the center of the
wand
Pneumatic Lithotripsy
• Like a jackhammer
• Depression of foot pedal forces compressed
air to handpiece
• Metal projectile is propelled
• Repetitive mechanical pounding
• Mechanical energy transferred to tip
• Fragmentation by compression forces
Success Rates PCNL
• Renal stones (even staghorns)
– 80-90%
• Proximal ureteral stones
– 85%
• Stone clearance rates are affected by renal
anatomy and adequacy of access
Access for PCNL
• In the US
– 80-90% by IR
– 10-20% by urology
– When IR involved, can be just for initial PCN tube
or they may also dilate the tract and place the
final PCN tube, highly variable
Contraindications to PCNL
• UTI
• Coagulopathy
• No safe access possible
Complications of PCNL
• Bleeding
– Kidney is very vascular – each one gets 10% of
cardiac output
Complications of PCNL
• Sepsis – highest risk is with infection stones
(struvite)
• Pneumo/Hydrothorax
– Highest risk with upper pole puncture
• Up to 10% of upper pole punctures in some studies
• Colon/Spleen injury
– Very rare
Laparoscopy / Open
• Rarely necessary in 2009
• Can use for extreme cases where compliance
is a concern
• Higher morbidity, worse cosmesis, longer
recovery
Questions?