Silent obstruction after extracorporeal piezoelectric lithotripsy

Irreversible Renal Function Impairment Due to Silent Ureteral Stones

OBJECTIVE

To evaluate if renal function loss and hydronephrosis due to a silent ureteral stone might be reversed.

MATERIALS AND METHODS

We prospectively selected patients with silent ureteral stones between January 2006 and January 2014. A silent case was considered if there were no specific or subjective symptoms related to the ureteral stone. Patient, stone, and kidney characteristics were evaluated preoperatively, 3 and 12 months postoperatively. Renal function was accessed in the same intervals with serum creatinine (SCr), glomerular filtration rate (GFR), and (99m)Tc-dimercaptosuccinic acid. Patients without complete pre- and postoperative evaluation were excluded. Primary end point was midterm progress of global and ipsilateral renal function. Secondary end points included the evaluation of renal and collecting system anatomy from diagnosis to 12 months after treatment. Analysis of variance with repeated measures and marginal homogeneity test were used to evaluate renal function and hydronephrosis progression.

RESULTS

Twenty-six patients met our inclusion criteria. Mean preoperative SCr and GFR were 1.24 mg/dL and 72.5 mL/min, respectively. At initial scintigraphy, mean renal function was 33.4%. Laser ureterolithotripsy was performed in 84.6% of cases and all patients were rendered stone free. Two patients (8%) developed ureteral stenosis. There was no difference regarding SCr (P = .89), GFR (P = .48), and renal function at scintigraphy (P = .19) during follow-up. Hydronephrosis significantly improved from preoperatively to 3 months postoperatively (P < .0001), but not from 3 to 12 months (P = .065).

CONCLUSION

Patients with silent ureteral stones present with significant impairment of ipsilateral renal function and hydronephrosis at diagnosis. On midterm follow-up evaluation, renal function of the affected unit remains stable whereas hydronephrosis improves after treatment.

Functional aspects of silent ureteral stones investigated with MAG-3 renal scintigraphy

Background

To investigate functional aspects of silent ureteral stones with special focus on obstruction and its relationship to renal anatomy. The present study is the first investigation of renal excretory function in patients with silent ureteral stones.

Methods

Patients with primarily asymptomatic ureteral stones underwent a mercapto-acetyltriglycine (MAG-3) renal scintigraphy prior to treatment, in addition to anatomic evaluation of renal units and serum creatinine levels. The primary outcome measure was the presence or absence of obstruction. Secondary outcome measures were kidney anatomy, grade of hydronephrosis, location of stones, stone size, and serum creatinine levels.

Results

During a ten-year period, 14 patients (median age 52.6 years; range 37.3 to 80.7 years) were included in the study. The relative frequency of primarily asymptomatic ureteral stones among all patients treated for ureteral stones in the study period was 0.7%. Eleven renal units showed some degree of hydronephrosis while 3 kidneys were not dilated. On the MAG-3 scan, 7 patients had an obstruction of the ureter, 5 had no obstruction, and 2 had dysfunction of the kidney. A statistically significant correlation was established between the grade of obstruction and stone size (p = 0.02).

Conclusions

At the time of presentation, only 64.3% of the patients revealed an obstruction in the stone-bearing renal unit. The degree of hydronephrosis and renal function were very diverse in this subgroup of patients with ureteral stones. The onset of ureterolithiasis and the chronological sequence of obstruction remain unclear in patients who have never experienced symptoms due to their stones.

Silent ureteral stones: impact on kidney function--can treatment of silent ureteral stones preserve kidney function?

OBJECTIVE

To report our experience with silent ureteral stones and expose their true influence on renal function.

METHODS

We analyzed 506 patients who had undergone ureterolithotripsy from January 2005 to May 2010. Silent ureteral stones were calculi found in the absence of any specific or subjective ureteral stone-related symptoms. Of the 506 patients, 27 (5.3%) met these criteria (global cohort). All patients were assessed postoperatively with dimercaptosuccinic acid scintigraphy (DMSA). A difference in relative kidney function of >10% was considered abnormal. Pre- and postoperative comparative DMSA analyses were electively obtained for 9 patients (kidney function cohort). A t test was used to assess the numeric variables, and the chi-square test or Fisher's exact test was used for categorical variables. Two-tailed P<.05 was considered statistically significant.

RESULTS

Stones were diagnosed by radiologic abdominal evaluation for nonurologic diseases in 40% and after previous nephrolithiasis treatment in 33%. The primary therapy was ureterolithotripsy in 88%. The mean follow-up time was 23 months. The overall ureteral stone-free rate after 1 and 2 procedures was 96% and 100%, respectively. In the global cohort, the mean pre- and postoperative serum creatinine levels were similar (P=.39), and the mean postoperative function on DMSA was 31%. In the kidney function cohort, no difference was found between the pre- and postoperative DMSA findings (22%±12.1% vs 20%±11.8%; P=.83) and serum creatinine (0.8±0.13 mg/dL vs 1.0±0.21 mg/dL; P=.45).

CONCLUSION

Silent ureteral stones are associated with decreased kidney function present at the diagnosis. Hydronephrosis tends to diminish after stone removal, and kidney function remains unaltered.

The Silence of the Stones: Asymptomatic Ureteral Calculi

PURPOSE

We investigated the characteristics and diagnosis of primary asymptomatic ureteral calculi.

MATERIALS AND METHODS

During a period of 12 years asymptomatic ureteral stones were prospectively investigated at the Urological Stone Center. We studied mode of diagnosis, stone size, localization, composition, hydronephrosis grade and patient characteristics.

RESULTS

Between 1995 and 2006 a total of 40 patients with asymptomatic ureteral stones were identified among 3,711 patients with ureteral stones (1.1%). Mean age of the 33 male and 7 female asymptomatic patients was 58.3 years (range 28.1 to 87.1). Localization of stones was 19 proximal, 3 mid and 18 in the distal ureter. Mean stone size was 10.0 mm (+/-6). Mode of diagnosis of asymptomatic calculi was randomly diagnosed hydronephrosis in 10 patients (25%), microscopic hematuria in 8 (20%), randomly diagnosed stone on other than urological x-ray examination in 13 (32.5%) and stone diagnosed during followup after previous nephrolithiasis in 9 patients (22.5%). Primary therapy was extracorporeal shock wave lithotripsy in 35 patients (87.5%), ureterorenoscopic lithotripsy in 4 (10%), spontaneous stone passage before scheduled treatment in 1 and open ureteroneocystostomy in 1 patient.

CONCLUSIONS

De novo asymptomatic ureteral calculi do exist. Characteristics of this small group of patients with ureterolithiasis have not been described thus far. Diagnosis is usually made during routine health care examinations, during the evaluation of nonurological diseases and during followup of patients who previously had nephrolithiasis. A large proportion of patients exhibit some degree of hydronephrosis as a sign of silent obstruction.

Scintigraphy and Doppler ultrasonography for the evaluation of obstructive urinary calculi

Forty-seven patients with unilateral obstructive calculi (12 males and 35 females) were submitted to 99mTc-diethylene triamine pentaacetic acid (DTPA) or 99mTc-dimercaptosuccinic acid (DMSA) scans for assessment of renal function. The scans revealed unilateral functional deficit in 68 and 66% of the patients, respectively. A calculus size of 1.1 to 2.0 cm was significantly associated with deficit detected by DTPA, but duration of obstruction and calculus localization were not. After relief of the obstruction, the mean percent renal function of the affected kidney was found to be significantly increased from 25 +/- 12% to 29 +/- 12% in DTPA and from 21 +/- 15% to 24 +/- 12% in DMSA. Initial Doppler ultrasonography performed in 35 patients detected an increased resistive index in 10 (29%). In the remaining patients with a normal resistive index, ureteral urinary jet was observed, indicating partial obstruction. The high frequency of renal function impairment detected by DTPA and of tubulointerstitial damage detected by DMSA as well as the slight amelioration of unilateral renal function after relief of obstruction suggest that scintigraphy assessment may help evaluate the unilateral percentage of renal function and monitor renal function recovery when it occurs. The presence of a urinary jet detected by Doppler ultrasonography further indicates the severity of obstruction and the recovery prognosis.