risk factors for the formation of a steinstrasse after shock wave lithotripsy

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Original Paper

Urol Int 2005;74:323–325 DOI: 10.1159/000084431

Risk Factors for the Formation of a Steinstrasse after Shock Wave Lithotripsy

Sedat Soyupek Abdullah Arma g ̆ an Alim Ko s ̧ ar T. Ahmet Serel M. Burak Ho s ̧ can Hakkı Perk Taylan Oksay

Department of Urology, Süleyman Demirel University Faculty of Medicine, Isparta , Turkey

spectively. The incidence rates of a steinstrasse in stones located in upper calices, middle calices, lower calices, and renal pelvis were 6.12, 10.52, 6.36, and 19.32%, re-spectively. Conclusions: Stone size and site are the sig-nifi cant factors predicting the formation of a steinstras-se. If a patient has a high probability of steinstrasse formation, close follow-up with early intervention or pro-phylactic pre-SWL ureteral stenting is indicated.

Copyright © 2005 S. Karger AG, Basel

Introduction

A steinstrasse is an accumulation of stone fragments obstructing the ureter after shock wave lithotripsy (SWL). It is a well-recognized complication of the SWL treatment [1] . A steinstrasse is usually transient and asymptomatic. But it may cause partial or complete obstruction, renal colics, urinary tract infection, and renal insuffi ciency. Currently SWL is widely used for the treatment of renal or ureteral calculi. Steinstrassen occur in 2–10% of the cases, with the incidence rising with increasing stone bur-den [1, 2] . Large stone burden, staghorn calculi, bilateral SWL, and pre-existing ureteral obstruction are known risk factors [2] . We studied the various stone, renal, and therapy factors that could predict steinstrasse formation after SWL.

Key Words Incidence rates, steinstrasse formation � Shock wave lithotripsy, complications � Steinstrasse, prediction

Abstract Introduction: We studied the various stone, renal, and therapy factors that could affect steinstrasse formation after shock wave lithotripsy (SWL) to defi ne their predic-tive value. Patients and Methods: Between May 1999 and September 2002, 563 patients were treated with a Stonelight V3 lithotriptor. A steinstrasse was recorded in 46 patients. All patient data, stone and renal characteris-tics, and data of SWL were reviewed. Statistical analyses of patients, stones, and therapy characteristics in corre-lation with the incidence of steinstrasse formation were performed to assign factors that had a signifi cant impact on the formation of this complication. Results: The over-all incidence of a steinstrasse was 8.17%. The steinstras-se was in the pelvic ureter in 84.3% of the cases, in the iliac ureter in 7.84% of them, and in pelvic and iliac ureter in 7.84% of the patients. The incidence of a steinstrasse signifi cantly correlated with stone size and site. The in-cidence rates of a steinstrasse in renal stones ! 1 cm, 1–2 cm, and 1 2 cm were 4.46, 15.87, and 24.3% respec-tively. The incidence rates of this complication in ure-teral stones ! 1 cm and 1–2 cm were 3.37 and 9.52%, re-

Received: August 19, 2004 Accepted: December 23, 2004 Internationalis

Urologia

Sedat Soyupek, MDDepartment of UrologySuleyman Demirel University HospitalTR–32050 Isparta (Turkey)Fax +90 246 2371762, E-Mail ssoyupek@hotmail.com

© 2005 S. Karger AG, Basel0042–1138/05/0744–0323$22.00/0

Accessible online at:www.karger.com/uin

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Soyupek/Arma g ̆ an/Ko s ̧ ar/Serel/Ho s ̧ can/Perk/Oksay

Urol Int 2005;74:323–325 324

Patients and Methods

Between May 1999 and September 2002, 563 patients were treated by means of a Stonelight V3 lithotriptor. Renal stones were present in 347 patients and ureteral stones in 216 patients. Stein-strassen were recorded in 46 patients, including 30 males (65.2%) and 16 females (34.8%). The mean age of the patients was 38.4 (range 10–71) years. Treatment was initiated at 9 kV, and energy was gradually increased by 0.5 kV to the maximum level (23 kV) that a patient could tolerate. Patients with congenital anomalies of the urinary tract, a history of previous surgery for urolithiasis, ap-parent metabolic disorders, staghorn calculi, and those treated with combined therapy with open surgery or percutaneous nephrolithot-omy were excluded from the study. Stone size, stone localization (renal or ureteral; upper, middle, or lower calices; pelvic), intrarenal stone number, and renal morphology parameters were recorded. Statistical analyses of patients, stones, and therapy characteristics in correlation with the incidence of steinstrasse formation were performed to assign factors that had a signifi cant impact on the oc-currence of this complication. A comparison between the group with and the group without a steinstrasse after the SWL treatment was done using chi-square and Fisher’s exact tests to assess the im-pact of the different factors on steinstrasse formation. Differences resulting in p ̂ 0.05 were considered statistically signifi cant.

Results

A steinstrasse developed 1 day to 2 months after stone fragmentation. The overall incidence was 8.17%. The steinstrasse was in the pelvic ureter in 84.3% of the cases, in the iliac ureter in 7.84% of them, and in the lumbar part of the ureter in 7.84% of the patients. The steinstras-se incidences in renal stones ! 1 cm, 1–2 cm, and 1 2 cm were 4.4, 15.7, and 24.3%, respectively. The steinstrasse incidences in patients with ureteral stones ! 1 cm and 1–2 cm were 2.7 and 8.8%, respectively. The steinstrasse incidences in upper, middle, and lower caliceal and renal pelvis stones were 4.1, 9.4, 6.4, and 18.8%, respectively. Statistical analyses of stones and renal morphology char-acteristics in correlation with the incidence of steinstras-se formation are shown in table 1 . The steinstrasse inci-dence signifi cantly correlated with stone size and intrare-nal stone localization (p ! 0.05). In contrast to ureteral stones, the steinstrasse incidence increases to a statisti-cally signifi cant degree, as the stone diameter becomes larger in patients with renal calculi. When assessed ac-cording to renal location, the probability of steinstrasse formation after SWL is statistically signifi cantly higher in patients with intrapelvic as compared with caliceal stones. There was statistically no difference, whether there were one or more renal stones, but renal stones caused stein-strasse formation signifi cantly more often than ureteral stones. The presence of pelvicaliceal dilatations was not statistically correlated with steinstrasse formation.

In our study, we placed routinely JJ stents before the SWL procedure in 33 cases whose stones were 1 2.5 cm. A steinstrasse was seen in 8 of these patients (24.2%). Catheter removal was necessary in 9 patients because of the catheter-related discomfort.

Discussion

SWL has been shown to be a safe and effective method for the treatment of most patients having upper urinary tract stones. Major complications, although few, include haemorrhage, septicaemia, steinstrasse formation, and cardiac arrhythmias [1] . Stone fragments that develop af-ter SWL may lodge within the ureter. This column of fragments is referred to as a ‘steinstrasse’. Appropriate use of percutaneous techniques, double-J stents, ureteros-copy, and aggressive use of antibiotics can minimize the potentially serious complications associated with SWL [3] .

Table 1. Stone and renal morphology characteristics in correlation with the incidence of steinstrasse formation (total n = 563)

Parameters Steinstrasse present(n= 46)

Steinstrasse absent(n = 517)

p

Renal morphologyNormalDilatation

2719

273242

0.53

Intrarenal stonesSingleMultiple

379

44176

0.38

Stone siteRenalUreteral

388

309208

0.0023

Ureteral stones^1 cm1–2 cm

53

17731

0.1142

Renal stones^1 cm1–2 cm>2 cm

82010

17110731

0.0001

Intrarenal localization of stonesUpper calicesMiddle calicesLower calicesIntrapelvic

277

22

4667

101 95

0.0055

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Steinstrasse Formation after Shock Wave Lithotripsy

Urol Int 2005;74:323–325 325

A steinstrasse occurs in 2–10% of the cases, with the incidence rising with increasing stone burden [1, 3, 4] . Our incidence of a steinstrasse was 6.3%. The steinstras-se was in the pelvic ureter in 78.3% of the cases, in the lumbar ureter in 13.86% of them, and in the iliac ureter in 7.84% of the patients. This distribution may be a result of the narrowing at the vesico-ureteric junction, which causes fragments to accumulate above it, or sometimes of ureteric/meatal stenosis.

A direct correlation was found between stone size and subsequent steinstrasse development [1, 2, 5] . The stein-strasse incidence rates in renal stones ! 1 cm, 1–2 cm, and 1 2 cm were 4.4, 15.7, and 24.3%, respectively. This rela-tionship to stone size was statistically confi rmed in our patients, but the stone size was not signifi cant in ureteral stones ! 1 cm and 1–2 cm.

The stone site had a statistically signifi cant impact on steinstrasse formation. Our results showed that there was a signifi cant correlation in steinstrasse formation between intracaliceal renal stones and intrapelvic stones. This may be explained by the fact that intrapelvic stones had a larger size than intracaliceal ones. There was a signifi -cant correlation in steinstrasse formation between renal (10.95%) and ureteral (3.7%) stones. Ureteral stones were more likely when fully disintegrated to pass spontane-ously with rapid elimination. This fi nding may be due to a higher ureteral peristaltic rate and a greater amplitude of peristaltic contractions as compared with the intrapel-vic activity [6] . There was no statistically signifi cant dif-ference between the number of stones (single or multiple) and the steinstrasse incidence in renal stones.

In order to decrease the steinstrasse incidence in pa-tients with a large stone burden, an indwelling ureteral

stent can be placed before the SWL procedure. It has been reported [7, 8] that placing an indwelling ureteral stent may lower the steinstrasse incidence in patients with a large stone burden. However, catheters may cause patient discomfort, and catheter obstruction may occur [9] . Thus a routine use of ureteral stents is generally not indicated. In our study, we placed routinely JJ stents in patients whose stones were 1 2.5 cm, and the steinstrasse incidence in these patients was 24.2%.

The renal morphology is another important factor that infl uences the process of elimination of stone fragments. Many studies revealed that a high renal intrapelvic pres-sure is associated with reduced or absent renal pelvic mo-tility and profound inhibition of pelvic and ureteral peri-stalsis [10] . Thus, radiologically dilated systems have less propulsive power and a decreased antegrade fl uid pres-sure with a higher probability of stone fragment stasis and prolonged calculus transit time. Madbouly et al. [10] found that the steinstrasse formation was 1.8 times less in normal than in dilated renal units, but in our study we found that the steinstrasse incidence rates were 9% in pa-tients with a normal renal morphology and 7.5% in those having hydronephrosis. There was no statistically signifi -cant difference between the two groups. The decreased ureteral peristaltic activity can be explained by the pro-pulsive effect of the higher intrapelvic pressure of kidneys with a normal parenchyma. This propulsive effect may push post-SWL fragments to the bladder.

To conclude, stone size and site are the signifi cant fac-tors predicting steinstrasse formation. If a patient has a high probability of steinstrasse formation, close follow-up with early intervention or prophylactic pre-SWL ureteral stenting is indicated.

References

1 Coptcoat MJ, Webb DR, Kellett MJ, Fletcher MS, McNicholas TA, Dickinson IK, Whitfi eld HN, Wickham JE: The complications of extra-corporeal shockwave lithotripsy: Management and prevention. Br J Urol 1986; 58: 578–580.

2 Weinerth JL, Flatt JA, Carson CC 3rd: Lessons learned in patients with large steinstrasse. J Urol 1989; 142: 1425–1427.

3 Roth RA, Beckmann CF: Complications of ex-tracorporeal shock-wave lithotripsy and percu-taneous nephrolithotomy. Urol Clin North Am 1988; 15: 155–166.

4 Sulaiman MN, Buchholz NP, Clark PB: The role of ureteral stent placement in the preven-tion of Steinstrasse. J Endourol 1999; 13: 151–155.

5 Fedullo LM, Pollack HM, Banner MP, Amen-dola MA, Van Arsdalen KN: The development of steinstrassen after ESWL: Frequency, natu-ral history, and radiologic management. AJR Am J Roentgenol 1988; 151: 1145–1147.

6 Ryan PC, Lennon GM, McLean PA, Fitzpat-rick JM: The effects of acute and chronic JJ stent placement on upper urinary tract motil-ity and calculus transit. Br J Urol 1994; 74:

434–439.

7 Bregg K, Riehle RA Jr: Morbidity associated with indwelling internal ureteral stents after shock wave lithotripsy. J Urol 1989; 141: 510–512.

8 Wolf S: Choice of Lithotriptor and Clinical Is-sues. AUA Guidelines 2003.

9 Libby JM, Meacham RB, Griffi th DP: The role of silicone ureteral stents in extracorporeal shock wave lithotripsy of large renal calculi. J Urol 1988; 139: 15–17.

10 Madbouly K, Sheir KZ, Elsobky E, Eraky I, Kenawy M: Risk factors for the formation of a steinstrasse after extracorporeal shock wave lithotripsy: A statistical model. J Urol 2002;

167: 1239–1242.

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