Urolithiasis (2015) 43:83–88 DOI 10.1007/s00240-014-0724-6


Ureteral wall thickness at the impacted ureteral stone site: a critical predictor for success rates after SWL Kemal Sarica · Alper Kafkasli · Özgür Yazici · Ali Cihangir Çetinel · Mehmet Kutlu Demirkol · Murat Tuncer · Cahit S¸ahin · Bilal Eryildirim 

Received: 13 August 2014 / Accepted: 15 September 2014 / Published online: 25 November 2014 © Springer-Verlag Berlin Heidelberg 2014

Abstract  The aim of the study was to determine the possible predictive value of certain patient- and stone-related factors on the stone-free rates and auxiliary procedures after extracorporeal shock wave lithotripsy in patients with impacted proximal ureteral calculi. A total of 111 patients (86 male, 25 females M/F: 3.44/1) with impacted proximal ureteral stones treated with shock wave lithotripsy were evaluated. Cases were retrieved from a departmental shock wave lithotripsy database. Variables analyzed included BMI of the case, diameter of proximal ureter and renal pelvis, stone size and Hounsfield unit, ureteral wall thickness at the impacted stone site. Stone-free status on follow-up imaging at 3 months was considered a successful outcome. All patients had a single impacted proximal ureteral stone. While the mean age of the cases was 46 ± 13 years (range 26–79 years), mean stone size was 8.95 mm (5.3–15.1 mm). Following shock wave lithotripsy although 87 patients (78.4 %) were completely stone-free at 3-month follow-up visit, 24 (21.6 %) cases had residual fragments requiring further repeat procedures. Prediction of the final outcome of SWL in patients with impacted proximal ureteral stones is a challenging issue and our data did clearly indicate a highly significant relationship between ureteral wall thickness and the success rates of shock wave lithotripsy particularly in cases requiring additional procedures. Of all the evaluated stone- and patient-related factors, only ureteral wall thickness at the impacted stone site independently predicted shock wave lithotripsy success.

K. Sarica · A. Kafkasli (*) · Ö. Yazici · A. C. Çetinel · M. K. Demirkol · M. Tuncer · C. S¸ahin · B. Eryildirim  Dr. Lutfi Kirdar Kartal Training and Research Hospital, Istanbul, Turkey e-mail: [email protected]

Keywords  Ureter · Stone · SWL

Introduction Impacted ureteral stone (s) are defined as the calculi remaining in the same position for a reasonable period of time (more than 1-month) and causing ureteral obstruction with lack of evident visualization beyond the stone on intravenous urography (IVU) [1–3]. Optimal management of these stones has been controversial for the urologists, and clinical introduction of minimally invasive treatment approaches has made the decision-making more complex than ever with no established guidelines [3–5]. Bringing the patient(s) into a completely stone-free status with limited or no morbidity is the ultimate goal and to achieve that, in addition to stone- (size and location) and patient-related factors, surgeon’s experience and the availability of particular technologies are the crucial factors that should be considered in an individual basis. Technological advancements in recent years have changed the management principles of impacted ureteral stones to a certain extent where less invasive procedures did gradually replace the open surgical approach [5, 6]. Related with this subject, extracorporeal shockwave lithotripsy (SWL), ureteroscopy, antegrade PCNL and rarely laparoscopic surgery are being performed to remove such stone (s) with some certain advantages and disadvantages [5–8]. Of these alternatives, currently both SWL and ureteroscopic lithotripsy are the most commonly applied procedures with acceptable and effective results [7, 9–11]. As an anesthesia-free alternative, SWL has been applied as a practical, non-invasive and effective method in the majority of upper urinary tract stones. However, despite all these advantages, this technique



achieves good results at the expense of repeated treatments in a certain percent of the cases making the total duration of the treatment longer than the other approaches. In addition, passage of the fragmented calculi may be causing colic pain and urinary symptoms that may pose further discomfort to the patients. Stone size is a crucial factor for the ultimate success of SWL and relevant studies did clearly demonstrate that the initial stone-free rate is decreased when the stone is large and impacted with high re-treatment rates [5, 7, 9, 11, 12]. Moreover, large and impacted ureteral stones have been found to be more resistant to shock wave disintegration because of insufficient water–stone interface and lack of the natural expansion space around such stones with reported stone-free rates of 45–60 % [13–15]. In addition, these stones are frequently associated with distal lesions such as stricture or polyps that may also further limit the chance of spontaneous passage of the fragments after SWL. Thus, taking the associated factors into account, prediction of the final SWL outcome in impacted proximal ureteral stones seems to be highly difficult. Although many studies focused mainly on the treated stone size, limited number of studies evaluated the efficacy of the procedure when the presence and degree of impaction are the main concerns. No study so far evaluated the possible predictive parameters for the final outcome of SWL in these cases focusing mainly on the presence and degree of impaction. In this present prospective study, we aimed to evaluate the possible predictive factors for the stone-free rates and the additional procedures after SWL application in impacted proximal ureteral stones to provide recommendations on the optimal treatment choice for their management.

Patients and methods Between January 2012 and December 2013, a total of 111 adult patients (86 males and 25 females: M/F: 3.44/1) with impacted proximal ureteral calculi were treated with SWL and included into the study program. All cases had a single impacted radio-opaque stone in the proximal ureter that failed to pass spontaneously causing recurrent renal colic and or obstruction. Patients with multiple stones, previous open surgery or endoscopic procedures for ureteral stones, previous SWL of a stone in the same ureter, stent placement, congenital anomalies, coagulopathy, or renal insufficiency were excluded from the study. Proximal portion of the ureter has been defined as the part of the ureter between the ureteropelvic junction and the lower border of the fourth lumbar vertebra. Prior to the treatment, a detailed information regarding the procedure and possible re-treatment sessions, additional procedures or complications had been explained to all patients and a written informed consent was obtained. In addition to a detailed history and thorough urogenital


Urolithiasis (2015) 43:83–88

Fig. 1  Non-contrast computed tomography (CT) demonstrating evident increase in ureteral wall thickness (UWT) around the large proximal ureteral stone

examination, biochemical evaluation (serum creatinine, blood urea nitrogen), bleeding profile, urinalysis and urine culture-sensitivity tests were performed. On the other hand, radiological investigations included plain X-ray of the kidney, ureter and bladder, ultrasound, excretory urography and computed tomography (CT) urography. All patients with positive urine culture were treated by proper antibiotics regimen before the procedure. Depending on the radiologic evaluation findings, the criteria of impaction were failure of visualization of the ureter distal to a proximal ureteral stone on IVU or CT urography, along with confirmation of the presence of the stone (and/or symptoms) in the same position more than 1 month. In addition to the body mass index (BMI) of all cases treated, all radiologic possible predictive parameters have been derived by making calculations from the IVU and CT performed prior to the procedure in all cases. In this regard, the size as well as the Hounsfield unit value have been calculated at first and particularly, the ureteric wall thickness at the impacted stone site (calculated from CT images) (Fig. 1a, b),

Urolithiasis (2015) 43:83–88


Table 1  Effect of the patient- and stone-related factors on the auxiliary procedures performed after SWL Age (year)

BMI (kg/m2)

SS (mm)

UWT (mm)

PUD (mm)

PAPD (mm)


AP no AP yes

44.9 ± 12,8 50.2 ± 10.7

25.9 ± 2.7 26.6 ± 3.5

8.48 ± 1.54 10.67 ± 2.00

2.98 ± 0.75 4.39 ± 0.81

9.03 ± 2.25 11.80 ± 2.15

22.3 ± 12.5 29.5 ± 7.8

619 ± 196 896 ± 211




Ureteral wall thickness at the impacted ureteral stone site: a critical predictor for success rates after SWL.

The aim of the study was to determine the possible predictive value of certain patient- and stone-related factors on the stone-free rates and auxiliar...
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