Use of Renal Ultrasound to Detect Hydronephrosis After Ureteroscopy

Dynamic renal scans as a modality for follow-up of flexible ureteroscopy

OBJECTIVE

To determine whether dynamic renal scans - DTPA or MAG3 - routinely performed after flexible ureteroscopies (f-URS) could detect the development of an obstruction and thus promote prompt early intervention for kidney preservation.

PATIENTS AND METHODS

In this retrospective study, with all the data recorded prospectively between April 2010 and October 2023, 250 renal units in 242 patients with upper urinary tract stones (UUTS) who underwent ureterorenoscopy by one surgeon in the same medical center were evaluated. Stone-free rate (SFR) was defined as no residual fragments at all using an intraoperative "triple test". The following characteristics were examined: gender, BMI, age, Hounsfield unit, stone diameter, laterality, renal/ureteral stones, stone-free rate, and auxiliary procedures per renal unit. The Clavien-Dindo classification was used to report complications. Renal units with residual stones were scheduled for a 2nd f-URS. Post- flexible ureteroscopy ureteral obstruction and renal function were detected using renal scan DTPA or MAG-3. The primary outcome was renal/ ureteral obstruction.

RESULTS

The mean patient age was 53 years. The mean stone size was 12.3 mm. Stones in renal pelvis, upper, middle and lower calyces were treated in 9.2% (23), 27.6% (69), and 30.8% (77) of cases, respectively; 44% (110) ureteral stones were also treated. The single- and second-session SFRs were 94.8% and 99.7%, respectively. A third auxiliary procedure was needed in one renal unit (0.4%). The mean number of procedures per renal unit was 1.06 (264/250). Ureteral double-J stents were inserted in 53.6% (134) of the cases. In 37 (14.8%) cases, a stent was placed before surgery. Post-operative complications were minor, with readmission and pain control needed in only two patients (0.8%). No avulsion or perforation of the ureters was observed. In six patients with t1/2 between 10-20 minutes, a second renal scan revealed spontaneous improvement and no obstruction in five patients. One patient with large stones and a history of prior ureteroscopy developed a ureteral stricture (0.4%) and needed treatment with laser endoureterotomy.

CONCLUSIONS

Post-flexible ureteroscopy obstruction due to ureteral stricture is very rare. A routine renal scan post-operatively may be used in potentially high-risk patients.

Is it safe to use a ureteral access sheath in an unstented ureter?

Background

The aim of this study was to examine ureteral stricture rate after the use of UAS in an unstented ureter and compare complications of smaller vs. larger-caliber UAS.

Methods

We conducted a retrospective analysis of consecutive RIRS for renal stones, with the use of UAS in unstented ureters. We excluded cases with previous ureteroscopies, who carried ureteral stent or nephrostomy, had impacted stones, underwent radiation treatment, or had urinary tract malignancies. The primary outcome was formation of ureteral strictures diagnosed by hydronephrosis in ultrasound test and late secretion in dynamic renal scan. Secondary outcome was stone-free-rate (SFR) and complications. In addition, we compared safety and efficacy of smaller (9.5/11.5Fr) vs. larger-caliber (12/14Fr) UAS.

Results

The cohort included 165 patients with a median follow-up time of 115 days. There was no case of ureteral stricture formation after the use us UAS, despite using a larger-caliber UAS in nearly half the cases. Larger-caliber UAS was not associated with more complications compared to the smaller-caliber one (p = 0.780). SFR was non-significantly higher in the larger-caliber UAS group (p = 0.056), despite having a larger stone burden, and only stone number was associated with SFR (p = 0.003).

Conclusions

These data suggest that the use of UAS during RIRS in an unstented ureter is safe and does not involve ureteral stricture formation after one procedure. Furthermore, the use of wider sheaths was not found to be associated with higher complications rate.

Modeling the Incidence of Secondary Malignancy Related to Ionizing Radiation Use in the Management of Nephrolithiasis

OBJECTIVE

To model the risk of secondary malignancy and associated mortality due to ionizing radiation from the evaluation and management of nephrolithiasis.

METHODS

A PUBMED-based literature search was performed to identify model inputs, specifically annual incidence of nephrolithiasis sub-stratified by age and gender and radiation exposure associated with nephrolithiasis episodes. Estimates of age and gender specific radiation-induced malignancy and mortality rates were obtained from the BEIR VII Phase 2 report with dose extrapolation using the linear no-threshold model.

RESULTS

Incidence of new diagnoses of nephrolithiasis ranged from 42/100,000 in males 20-30 years old to 248/100,000 in males 60-70 years old. Radiation exposure per nephrolithiasis episode was 37.3 mSv over a 2-year period. Data regarding average stone episodes per patient with nephrolithiasis was limited and conservatively estimated at 1.5. Modeled lifetime attributable risk of secondary malignancy and subsequent mortality in individual stone patients ranged from 0.096% and 0.085%, respectively, in males over the age of 70 to 0.59% and 0.39% in females 20-30 years old. In the USA, overall incidence of secondary malignancy and associated mortality related to nephrolithiasis management was calculated to be 862.7 and 545.3 cases/year, respectively.

CONCLUSION

This model suggests that ionizing radiation from the management of nephrolithiasis carries a small but significant risk of causing secondary malignancy. This knowledge must be considered when using modalities that involve radiation in the diagnosis and therapeutic management of nephrolithiasis.

Radiation Mitigation Techniques in Kidney Stone Management

Patients with nephrolithiasis are exposed to significant quantities of ionizing radiation with the potential to cause secondary malignancy. This risk is magnified by the high recurrence rate of nephrolithiasis. In this article, we identify the risks of ionizing radiation as they pertain to patients with nephrolithiasis. We then identify evidence-based techniques for mitigating patient radiation exposure in the preoperative, intraoperative, and postoperative settings. Key factors include limiting the use of computed tomographic imaging, appropriate modulation of fluoroscopy settings, and minimizing rates of stone recurrence.

Are antibiotics necessary during routine cystoscopic stent removal?

BACKGROUND

The 2008 American Urological Association (AUA) Best Practice Statement on antimicrobial prophylaxis states that prophylaxis is not warranted for subjects with normal risk profile undergoing cystourethroscopy unless manipulation such as ureteral stent removal is performed. To date no studies have specifically assessed the need for antimicrobial prophylaxis during cystoscopic ureteral stent removal. We sought to determine the risk of infectious complications following cystoscopic stent removal with and without antimicrobial prophylaxis.

METHODS

A retrospective review identified 70 subjects who underwent cystoscopic ureteral stent removal following kidney stone treatment, under the care of two separate urologists with differing practice patterns. Each cohort consisted of 35 subjects: with and without prophylactic antibiotics. Clinical variables assessed included demographics, type of stone intervention, prior urinary tract infection (UTI) history, immunocompromising comorbidities, antimicrobial class at time of stone intervention, and antimicrobial administration at cystoscopic stent removal. The primary outcome assessed was development of symptomatic UTI within 4 weeks after stent removal.

RESULTS

Overall, 35 patients (50%) received antimicrobial prophylaxis at the time of stent removal and 35 (50%) did not receive antimicrobial prophylaxis, with no demographic or clinical differences between cohorts. Two patients in the antimicrobial cohort (6%) developed a UTI and none of the patients who did not receive antimicrobial prophylaxis developed a UTI (P=0.15).

CONCLUSIONS

In our cohort study antimicrobial prophylaxis at the time of cystoscopic stent removal did not appear to provide a significant benefit in UTI prevention. Prospective studies would assist in validating these findings.

Clinical factors associated with postoperative hydronephrosis after ureteroscopic lithotripsy

Purpose

This study aimed to determine the predictors of ipsilateral hydronephrosis after ureteroscopic lithotripsy for ureteral calculi.

Materials and Methods

From January 2010 to December 2014, a total of 204 patients with ureteral calculi who underwent ureteroscopic lithotripsy were reviewed. Patients with lack of clinical data, presence of ureteral rupture, and who underwent simultaneous percutaneous nephrolithotomy (PNL) were excluded. Postoperative hydronephrosis was determined via computed tomographic scan or renal ultrasonography, at 6 months after ureteroscopic lithotripsy. Multivariable analysis was performed to determine clinical factors associated with ipsilateral hydronephrosis.

Results

A total of 137 patients were enrolled in this study. The mean age of the patients was 58.8±14.2 years and the mean stone size was 10.0±4.6 mm. The stone-free rate was 85.4%. Overall, 44 of the 137 patients (32.1%) had postoperative hydronephrosis. Significant differences between the hydronephrosis and nonhydronephrosis groups were noted in terms of stone location, preoperative hydronephrosis, impacted stone, operation time, and ureteral stent duration (all, p<0.05). On multivariable analysis, increasing preoperative diameter of the hydronephrotic kidney (adjusted odds ratio [OR], 1.21; 95% confidence interval [CI], 1.12–1.31; p=0.001) and impacted stone (adjusted OR, 3.01; 95% CI, 1.15–7.61; p=0.031) independently predicted the occurrence of postoperative hydronpehrosis.

Conclusions

Large preoperative diameter of the hydronephrotic kidney and presence of impacted stones were associated with hydronephrosis after ureteroscopic stone removal. Therefore, patients with these predictive factors undergo more intensive imaging follow-up in order to prevent renal deterioration due to postoperative hydronephrosis.

Office ultrasound for the urologist

Imaging of the genitourinary tract is essential in the workup of the majority of the conditions seen daily by urologists. The use of ultrasound in the office provides a safe, low cost, and efficient way for the clinician to evaluate the patient in real time. Ultrasound can allow for bedside diagnosis in many conditions and assist in treatment planning. This chapter covers the major applications of office ultrasound for the urologist as well as discusses future applications of ultrasound for the office setting.

Effectiveness of ultrasonography in the postoperative follow-up of pediatric patients undergoing ureteroscopic stone manipulation

OBJECTIVES

To evaluate the effectiveness of ultrasonography and to determine whether ionizing radiation is necessary in the postoperative follow-up of children undergoing ureteroscopy.

METHODS

We reviewed the charts of 49 children who underwent 51 ureteroscopic procedures for ureteral calculi. Renal ultrasound and intravenous urography were performed in all patients at 3 months after surgery for postoperative evaluation.

RESULTS

In three cases, stones migrated to the kidney. Retrograde intrarenal surgery was performed in two patients and one patient required shockwave lithotripsy to become stone-free. Fourty-six children were completely stone-free and 3 had residual fragments on plain film in the postoperative 3 month. The sensitivity, specificity, negative and positive predictive values of ultrasonography for detecting hydronephrosis were 85.7, 100, 97.7 and 100%, respectively. Two patients under observation and three patients under medical expulsive therapy had resolution of hydronephrosis on follow-up. One patient required ureteroscopy for residual obstructing fragments.

CONCLUSIONS

Ultrasonography has limited accuracy for detecting residual ureteral stones, but it is a highly specific and reasonably sensitive test for detecting hydronephrosis. A combination of ultrasonography and plain film is a safe and effective imaging procedure in postoperative follow-up of children undergoing ureteroscopy.