Ureteroscopy (URS) vs. Shock Wave Lithotripsy (SWL) - Ureteral Strictures and Risk Factors

Question 1

What is the rate of ureteral strictures following URS and SWL?

Answer 1

URS: 2.9%, SWL: 1.5%.

Question 2

What is the risk of ureteral strictures with multiple URS procedures?

Answer 2

3.6%.

Question 3

How can high-powered lasers increase the risk of strictures in URS?

Answer 3

They increase energy levels and fluid temperature, potentially causing ureteral wall damage.

Question 4

Why is preoperative hydronephrosis a significant predictor of ureteral strictures?

Answer 4

It’s likely due to increased stone impaction and a higher risk of ureteral injury.

Question 5

How does having both kidney and ureteral stones affect stricture risk compared to ureteral stones alone?

Answer 5

Stricture risk is higher with both stones due to increased instrumentation and complexity.

Question 6

How do alpha blockers help reduce complications during URS?

Answer 6

They reduce the need for ureteral dilation and improve ureteroscopic access to stones.

Question 7

What is the main concern with a ureteral stricture that goes undiagnosed?

Answer 7

Silent obstruction leading to loss of renal function.

Question 8

Why is postoperative imaging recommended after URS?

Answer 8

To detect silent obstruction or ureteral strictures early and prevent renal damage.

Question 9

What percentage of patients undergoing URS with a ureteral access sheath (UAS) develop ureteral injury?

Answer 9

46.5%.

Question 10

What is the median time to ureteral stricture diagnosis after URS compared to SWL?

Answer 10

URS: 21 days (IQR: 4-100), SWL: 42 days (IQR: 13-148).

Question 11

Question 1
The utilization of which treatment increased over time:

Choose one

Ureteroscopy (URS)

Shock wave lithotripsy (SWL)

URS and SWL

Rates of treatment with each procedure remained steady over time

Answer 11

The correct answer is:

Ureteroscopy (URS)

The utilization of Ureteroscopy (URS) has steadily increased from 38% in 2008 to 58% in 2019, as noted in the study data. This shift reflects the growing preference for URS over Shock Wave Lithotripsy (SWL) due to advances in instrumentation and technology. SWL usage has remained relatively steady or declined over the same period, making URS the procedure with the most significant increase in usage over time.

SWL has not shown a similar increase over time. In fact, the preference has shifted away from SWL toward URS, leading to the decline in SWL’s relative utilization.

Question 12

Question 2
The overall rate of stricture over time:

Choose one

Decreased

Remained stable

Increased

Was not assessed

Answer 12

The correct answer is:

Remained stable

According to the study, the overall rate of ureteral stricture following Ureteroscopy (URS) remained stable over the years of the study, despite the increasing utilization of URS. Although there was concern that factors such as high-powered lasers might increase stricture risk, the data did not show a significant change in stricture rates during the study period.

If the rate had increased over time, we would expect to see a higher incidence of strictures correlating with the increased use of URS, but that was not observed.

Question 13

Question 3
Based on the multivariable model of risk factors, which characteristic significantly increased the risk for ureteral stricture:

Choose one

URS, compared with SWL

Men 75 years and older

No prior stone history, compared with prior stone history

Previous treatment with SWL, compared with no prior treatment

Answer 13

The correct answer is:

URS, compared with SWL

Explanation:
According to the multivariable model, Ureteroscopy (URS) had a 1.7 times higher risk of causing ureteral strictures compared to Shock Wave Lithotripsy (SWL). This indicates that URS is a significant predictor for strictures due to the instrumentation and potential ureteral injury involved in the procedure.

Counter-Example:
Factors like age (such as men 75 years and older) and prior stone history also influence stricture risk but are not as strongly associated with strictures as URS itself when compared to SWL. Similarly, prior treatment with SWL did not increase the risk as significantly as URS.

Question 14

Question 4
What was the most common treatment among individuals who were diagnosed with a ureteral stricture:

Choose one

​​​Drainage only

Endoscopic treatment

Reconstruction

Nephrectomy

Answer 14

The correct answer is:

Drainage only

Explanation:
Among individuals diagnosed with a ureteral stricture, the most common treatment was drainage only, with 51% of cases requiring this intervention. This typically involved the placement of ureteral stents or nephrostomy tubes to relieve the obstruction.

Counter-Example:
Other treatments such as endoscopic treatment (19%), reconstruction (3%), and nephrectomy (1%) were less common, highlighting that drainage was by far the most frequent management approach.

Question 15

Question 5
Among patients who developed a ureteral stricture, patients who underwent URS were significantly more likely to undergo which procedures, compared with patients who underwent SWL:

Choose one

Drains and endoscopic treatment

Drains and reconstructive treatment

Endoscopic treatment and nephrectomy

Major reconstructive surgery and nephrectomy

Answer 15

The correct answer is:

Major reconstructive surgery and nephrectomy

Patients who developed a ureteral stricture after URS were significantly more likely to undergo major reconstructive surgery and nephrectomy compared to those who underwent SWL. This suggests that the severity of strictures caused by URS often necessitated more extensive and invasive interventions to manage the complication.

While drains and endoscopic treatments were common among all groups, they were not as significantly associated with URS as reconstructive surgery and nephrectomy, which were more likely to be required due to the complex nature of strictures following URS.