Secondary signs of non-enhanced CT prior to laser ureterolithotripsy: is treatment outcome predictable?

Outcomes of primary ureteroscopic lithotripsy: The role of maximum ureteral wall thickness at the site of stone impaction

OBJECTIVES

To verify if the maximum thickness of the ureteral wall at the stone site (m-UWT) can affect the outcomes of primary retrograde ureteroscopic lithotripsy (P-URSL) within a single-center dataset.

MATERIAL AND METHODS

We retrospectively reviewed data on 354 consecutive URSL performed from January 2020 to May 2022 at "Fondazione Poliambulanza" in Brescia (Italy). We included patients older than 18 years who underwent URSL for a single ureteral stone with a maximum diameter ranging from 5 to 10 mm. Patients with anatomical abnormalities, a positive preoperative urinary culture, or without a NCCT performed during the acute event were excluded. Patients were treated in an emergency setting (P-URSL within 48 h from the diagnosis of acute ureteral colic) or in a delayed one (D-URSL after a period of maximum 90 days of ureteral double-j stenting). For the resulting 139 patients we recorded demographic, clinical and stone-related features and perioperative data. We processed these data by univariate and multivariate analysis, and with a logistic regression analysis.

RESULTS

Of the 139 included procedures, 63 were P-URSL and 76 D-URSL. At the univariate analysis we found that stone diameter (OR 0.845, p = 0.017), stone volume (OR 0.023, p = 0.001), stone density (OR 0.998, p = 0.000) and m-UWT (OR 0.499, p = 0.013) are predictors of P-URSL. Stone density (OR 0.998, p = 0.002) is an independent predictor of P-URSL at the multivariate analysis. At a logistic regression analysis, a distal ureteric position (OR 0.189, p = 0.014), stone diameter (OR 1.289, p = 0.006), and m-UWT (OR 2.297, p = 0.02) were found to be statistically significant predictors of incomplete stone clearance in patients undergoing P-URSL. m-UWT is the only predictor of short-term postoperative adverse events in patients undergoing P-URSL (OR 3.386, p < 0.001). From a descriptive analysis, it emerged that an increased m-UWT (>2 mm) significantly correlates to an endoscopic finding of ureteritis' signs and to an increase in operative time, hospital stay and post-procedural stenting time. A m-UWT greater than 2 mm also correlates with a lower stone free rate (SFR) and with a significant increase in both short and long-term postoperative complications.

CONCLUSIONS

Our study confirmed a connection between m-UWT and poor endoscopic findings, as well as a direct correlation with the main morphometric parameters of the stone and finally with the outcomes of P-URSL itself. Further studies are necessary to validate our results, so that m-UWT might be routinely considered a useful tool in the decision-making process for P-URSL.

The association between ureteral wall thickness and need for additional procedures after primary ureteroscopy in patients with ureteral stones above the iliac crest

PURPOSE

To examine the parameters affecting the need for additional procedures in the primary ureteroscopy treatment in patients with ureteral stones above the iliac crest level.

METHODS

Seventy-one patients were included in the study who were ≥ 18 years old and had undergone ureteroscopy (URS) for ureteral stones above the iliac crest level between 2018-2020 and had a non-contrast-enhanced abdominal computed tomography before the procedures were included in the study. Patients and stone characteristics were prospectively collected. The results were evaluated six weeks after URS. The absence of any residual fragment was thought to indicate stone-free status. The patients with failure were referred for the additional procedures.

RESULTS

The median patient age was 51 years [interquartile range (IQR): 18-66]. The median transverse stone diameter was 9.5 mm (IQR: 7.1-11.4), and the median ureteral wall thickness (UWT) was 5.8 mm (IQR: 4.3-6.5). In the univariate analysis, UWT (p < 0.001), presence of multiple stones (p = 0.008), and stone length (p = 0.022) affected stone-free status. The multivariate analysis revealed UWT as the only independent factor affecting the need for additional procedures after URS (p = 0.028). In the receiver operating characteristic curve analysis, the best threshold value for UWT according to the outcomes was identified as 5.8 mm.

CONCLUSION

Ureteral wall thickness was the only independent parameter determining the need for additional procedures and affecting the treatment outcomes after the URS procedure.

Value of preoperative ureteral wall thickness in prediction of impaction of ureteric stones stratified by size in laser ureteroscopic lithotripsy

OBJECTIVES

To evaluate the role of preoperative UWT in the prediction of impaction of ureteral stones stratified according to stone size in ureteroscopic laser lithotripsy.

PATIENT AND METHODS

This study included 154 patients submitted to URSL for ureteral stones. Radiological data comprised the presence of hydronephrosis, anteroposterior pelvic diameter (PAPD), proximal ureteric diameter (PUD), and maximum UWT at the stone site. Collected stone characteristics were stone size, side, number, site, and density.

RESULTS

The study included 154 patients subjected to URSL. They comprised 74 patients (48.1%) with impacted stones and 80 (51.9%) with non-impacted stones. Patients were stratified into those with stone size ≤ 10 mm and others with stone size > 10 mm. In the former group, we found that stone impaction was significantly associated with higher PAPD, PUD, and UWT. In patients with stone size > 10 mm, stone impaction was related to higher UWT, more stone number, and higher frequency of stones located in the lower ureter. ROC curve analysis revealed good power of UWT in discrimination of stone impaction in all patients [AUC (95% CI) 0.65 (0.55-0.74)] at a cut-off of 3.8 mm, in patients with stone size ≤ 10 mm [AUC (95% CI) 0.76 (0.61-0.91)] at a cut-off of 4.1 mm and in patients with stone size > 10 mm [AUC (95% CI) 0.72 (0.62-0.83)] at a cut-off of 3.0 mm.

CONCLUSIONS

Stratifying ureteric stones according to size would render UWT a more practical and clinically-oriented approach for the preoperative prediction of stone impaction.

A novel model using computed tomography parameters to predict shock wave lithotripsy success in ureteral stones at different locations

OBJECTIVE

To combine non-contrast computerized tomography (NCCT)-based parameters with stone and patient characteristics that are already known to affect shock wave lithotripsy (SWL) success and assess this novel model's effectiveness in predicting SWL success for single ureteral stones in different locations.

MATERIALS AND METHODS

Data of patients treated by SWL for a single ureteral stone between January 2017 and January 2019 were retrospectively reviewed. Demographic parameters of patients and stone characteristics were combined with NCCT-based parameters. NCCT-based parameters included the presence or absence of hydronephrosis, perinephric stranding, periureteral edema, diameter of the proximal ureter, ureteral wall thickness (UWT) at ureteral stone site. The logistic regression method was used for the development of a useful predictive model. Subsequently, the receiver operating curve was used to determine cut-off levels, and a scoring system was developed for prediction of SWL success.

RESULTS

Stone-free rate was 77,1% (267/346) in the entire cohort. Univariate analysis revealed that age, stone volume, density, perinephric stranding, diameter of proximal ureter, and UWT, were associated with SWL success. In multivariate analysis, proximal ureteral stone location, stone volume, density, and UWT were independent predictors of SWL success. The formula used during logistic regression analysis was: 1/[1 + exp {-8.856 + 0.008 (stone volume) + 0.002 (stone density) + 0.673 (UWT) + 1026 (proximal ureteral stone)}]. The scores of 0, 1, 2, 3 and 4 were associated with 97,8%, 83,4%, 60,8%, 33,2% and 11,1% success rates, respectively, in the prediction model based on these parameters.

CONCLUSION

We conclude that our model can facilitate decision-making for SWL treatment of ureteral stones in different locations.

Ureteral Wall Thickness as a Preoperative Indicator of Impacted Stones in Patients With Ureteral Stones Undergoing Ureteroscopic Lithotripsy

OBJECTIVE

To evaluate the clinical significance of ureteral wall thickness (UWT) to predict the presence of impacted stones in patients with ureteral stones undergoing ureteroscopic lithotripsy (URSL).

MATERIALS AND METHODS

We retrospectively analyzed 130 procedures in patients with ureteral stones who underwent URSL between January 2014 and September 2016. Maximum UWT at the stone site was measured from computed tomography images. Clinical predictors of impacted stones were assessed using univariate and multivariate logistic regression analyses. Receiver operating characteristic curve analysis was applied to determine the UWT cutoff value and to evaluate its accuracy in predicting impacted stones. Moreover, we evaluated the association between UWT and endoscopic findings, as well as surgical outcomes.

RESULTS

Of the 130 procedures, 50 (38.5%) involved patients with impacted stones. The univariate analysis showed significant differences in age, hydronephrosis, stone location, stone burden, and UWT in patients with and without impacted stones, and the multivariate analysis showed that age, stones in the middle ureter, and UWT (odds ratio 5.43, P < .001) were independent predictors of impacted stones. The receiver operating characteristic analysis showed that 3.49 mm was the optimal cutoff value for UWT, with a predictive accuracy of 0.87. High UWTs were associated with the presence of ureteral edema, polyps, white lesions, stone fixation, longer operation time, and lower endoscopic stone-free rate, compared with low UWTs (P < .05 each).

CONCLUSION

High UWT is associated not only with a higher risk of impacted stones but also with poor endoscopic findings and adverse surgical outcomes in patients with ureteral stones undergoing URSL.

Evaluating the Patient with Left Lower Quadrant Abdominal Pain

Left lower quadrant pain is a frequent indication for imaging in the emergency department. Most causes of pain originate from the colon, including diverticulitis, colitis, fecal impaction, and epiploic appendagitis. Left-sided urolithiasis and spontaneous hemorrhage in the retroperitoneum or rectus sheath are additional causes of pain. Computed tomography is the preferred imaging modality in the emergent setting for all of these pathologic conditions. Gynecologic, testicular, and neoplastic pathology may also cause left lower quadrant pain but are not discussed in this article.

Predictive Value of Preoperative Unenhanced Computed Tomography During Ureteroscopic Lithotripsy: A Single Institute's Experience

Purpose

Ureteroscopic stone removal is frequently used to remove ureteral stones. Mucosal edema and bleeding are the two most important obstacles to a successful operation. This study analyzed relationships between unenhanced computed tomography (UECT) findings and ureteroscopic findings to determine whether ureteroscopic results could be predicted preoperatively by using UECT imaging.

Materials and Methods

From January 2009 to July 2011, 675 patients were diagnosed with ureteral stones through UECT. Among them, we retrospectively reviewed 92 cases of patients who underwent ureteroscopy (URS). We identified findings such as hydronephrosis, rim sign, periureteral fat stranding, and perinephric fat stranding on the UECT and then categorized these findings into four categories (none, mild, moderate, and severe) according to their severity. We also divided the URS findings of mucosal edema and bleeding into four categories (none, mild, moderate, and severe) and compared these findings with the UECT images.

Results

A total of 92 study patients were included in this study: 59 were male and 33 were female patients. According to the location of the stone, 31 cases were classified as upper ureteral stones, 15 were midureteral stones, and 46 were lower ureteral stones. Hydronephrosis identified with UECT was correlated with the mucosal edema severity observed during URS (p=0.004). The rim signs identified with UECT were proportional to the grade of mucosal edema (p=0.010).

Conclusions

Hydronephrosis and rim signs observed during UECT can be used as a predictive factor for intraoperative mucosal edema in patients undergoing URS.

Computed tomography-based novel prediction model for the stone-free rate of ureteroscopic lithotripsy

The purpose of this study was to evaluate whether computed tomography (CT) parameters can predict the success of ureteroscopic lithotripsy (URSL) and establish a model for predicting the success rates of a single URSL procedure for the treatment of a single ureteral stone. We retrospectively reviewed the records of 237 patients who underwent URSL for ureteral stones diagnosed by CT between January 2009 and June 2012. Stone-free status was defined as the absence of stones or residual stone fragments <2 mm by ureteroscopy and plain abdominal radiography. We analyzed the correlations between the outcome of URSL and the patients' sex, age, height, body weight, body mass index, and history of ureteral stone. Stone factors such as the diameter (D), stone height (H), volumetric stone burden (VSB; D(2) × H × 5 mm × π × 1/6), estimated stone location (ESL; number of axial cut images between the stone and uretero-vesical junction), tissue rim sign (RS; 0-3), perinephric edema (0-3), hydronephrosis (0-3), and Hounsfield unit (HU) were also analyzed. We then developed a model to predict the probability of successful URSL by applying a logistic model to our data. The success rate of URSL was 85.7% (203/237). Univariate analysis found that stone diameter, length, VSB, ESL, HU and RS significantly affected the stone-free rate. Multivariate analysis indicated that stone diameter, ESL and RS independently influenced the stone-free rate. The logistic model indicated that success rates = 1/[1 + exp{-6.146 + 0.071(D) + 0.153(ESL) + 1.534(RS)}] with an area under the receiver operating characteristic curve of 0.825. Stone diameter, ESL, and RS were independent predictors of the outcome of a single URSL for a single ureteral stone.

Predictive factors of the outcome of extracorporeal shockwave lithotripsy for ureteral stones

Purpose

Extracorporeal Shock Wave Lithotripsy (ESWL) has shown successful outcomes for ureteral stones. We investigated predictive factors for failure of ESWL for treating ureteral stones.

Materials and Methods

A total of 153 patients who underwent ESWL between July 2006 and July 2009 for ureteral stones diagnosed by non-enhanced spiral computed tomography were divided into two groups: (group A, stone size ≤10 mm; and group B, stone size >10 mm). The failure was defined as remnant stones >4 mm. We assessed age, sex, body mass index, stone size, laterality, location, skin-to-stone distance (SSD), Hounsfield unit, and the presence of secondary signs (hydronephrosis, renal enlargement, perinephric fat stranding, and tissue rim sign). We analyzed predictive factors by using logistic regression in each group.

Results

The success rates were 90.2% and 68.6% in group A and B, respectively. In the univariate analysis of each group, stone size, SSD, and all secondary signs showed statistically significant differences in terms of the outcome of ESWL (p<0.05). In the multivariate logistic regression, stone size (odds ratio [OR], 50.005; 95% confidence interval [CI], 6.207 to 402.852) was an independent predictive factor in group A. The presence of perinephric fat standing (OR, 77.634; 95% CI, 1.349 to 446.558) and stone size (OR, 19.718; 95% CI, 1.600 to 243.005) were independent predictive factors in group B.

Conclusions

Stone size is an independent predictive factor influencing failure of ESWL for treating ureteral stones. In larger ureteral stones (>10 mm), the presence of perinephric fat stranding is also an independent predictive factor.

Comparison of secondary signs as shown by unenhanced helical computed tomography in patients with uric acid or calcium ureteral stones

Unenhanced helical computed tomography (UHCT) has evolved into a well-accepted diagnostic method in patients with suspected ureterolithiasis. UHCT not only shows stones within the lumen of the ureter, it also permits evaluation of the secondary signs associated with ureteral obstruction from stones. However, there we could find no data on how secondary signs might differ in relation to different compositions of ureteral stones. In this study, we compared the degree of secondary signs revealed by UHCT in uric acid stone formers and in patients forming calcium stones. We enrolled 117 patients with ureteral stones who underwent UHCT examination and Fourier transform infra-red analysis of stone samples. Clinical data were collected as follows: age, sex, estimated glomerular filtration rate (eGFR), urine pH, and radiological data on secondary signs apparent on UHCT. The uric acid stone formers had significantly lower urine pH and eGFR in comparison to calcium stone formers, and on UHCT they also had a higher percentage of the secondary signs, including rim sign (78.9% vs. 60.2%), hydroureter (94.7% vs. 89.8%), perirenal stranding (84.2% vs. 59.2%) and kidney density difference (73.7% vs. 50.0%). The radiological difference was statistically significant for perirenal stranding (p=0.041). In conclusion, we found that UHCT scanning reveals secondary signs to be more frequent in patients with uric acid ureteral stones than in patients with calcium stones, a tendency that might result from an acidic urine environment.