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STONE
DISEASE
Appropriate
Cutoff for Treatment of Distal Ureteral Stones by Single Session In Situ
Extracorporeal Shock Wave Lithotripsy
Akhtar S, Ather MH
Department of Surgery, Aga Khan University, Karachi, Pakistan
Urology. 2005; 66: 1165-8
- Objectives:
To determine an appropriate cutoff for treatment by single
session in situ extracorporeal shock wave lithotripsy for a prevesical
stone by determining the differences in the efficiency quotient (EQ).
- Methods:
This was a review of a series of patients who underwent shock wave lithotripsy
for a primary, single, prevesical stone from January 1995 to June 2003.
All 153 patients were treated using a Dornier MPL 9000 lithotripter
in the prone position under intravenous sedation. The stone size was
measured in two dimensions (parallel and perpendicular to the long axis
of the ureter). The EQ was calculated using a standard formula.
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Results:
Of the 153 patients, 141 (92.2%) were stone free within a mean period
of 12.2 +/- 12.2 days (EQ 68.8). No significant complications occurred,
and none of the patients required admission. The treatment failed in
10 patients (6.5%), who subsequently required an ancillary procedure
(ureteroscopy). Statistically, we found 7 mm to be an appropriate cutoff
for treatment using in situ shock wave lithotripsy. The EQ for stones
greater than 7 mm and those 7 mm or smaller was 58 and 81, with a stone-free
period of 13.6 +/- 12.9 and 10.9 +/- 11.6 days, respectively.
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Conclusions:
Ultrasound-guided shock wave lithotripsy is an efficient and safe modality
for the treatment of prevesical stones 7 mm or less. Using an echo-guided
lithotripter, the treatment was a radiation-free, day care procedure
performed under intravenous sedation. Only 11% of our patients required
repeat treatment.
- Editorial
Comment
The optimal treatment of distal ureteral stones remains one of the more
controversial topics in endourology. Both procedures are associated
with high success rates and low complication rates. In situ SWL with
the Dornier HM3 has been shown in a number of series to be associated
with remarkably high stone free rates and low retreatment rates, even
for stones up to 15 mm in size (1,2). Although high stone free rates
have also been achieved with third generation lithotripters, retreatment
rates, particularly for larger stones, have been higher than in HM3
series. Akhtar & Ather compared stone free and retreatment rates
for in situ SWL of distal ureteral stones £ 7 mm or > 7 mm
in size in a retrospective analysis of 153 patients treated with a MPL9000
lithotripter. Although stone free rates were quite high in both size
categories (95% versus 89%, respectively), retreatment rates were significantly
higher in the larger stone group (45% versus 11%, respectively), translating
into an efficiency quotient of 81 for treatment of stones £ 7
mm and 58 for stones > 7mm. Although this size cutoff was chosen
randomly, it provides a reasonable algorithm to guide treatment of distal
ureteral calculi when considering treatment with a third generation
lithotripter. For stones £ 7 mm in size, ureteroscopy or in situ
SWL are certainly reasonable treatment options. However, for stones
> 7 mm in size, the high success rate and low retreatment rate of
ureteroscopy makes this treatment option more attractive then SWL if
an HM3 is not available.
References
1. Hochreiter WW, Danuser H, Perrig M, Studer UE: Extracorporeal shock
wave lithotripsy for distal ureteral calculi: what a powerful machine
can achieve. J Urol. 2003; 169: 878-80.
2. Pearle MS, Nadler R, Bercowsky E, Chen C, Dunn M, Figenshau RS, Hoenig
DM, McDougall EM, Mutz J, Nakada SY, Shalhav AL, Sundaram C, Wolf JS Jr.,
Clayman RV: Prospective randomized trial comparing shock wave lithotripsy
and ureteroscopy for management of distal ureteral calculi. J Urol. 2001;
166: 1255-60.
Dr.
Margaret S. Pearle
Associate Professor of Urology
University of Texas Southwestern Med Ctr
Dallas, Texas, USA |