Canadian Urological Association guideline: Management of ureteral calculi Flashcards
1
Q
What is the contemporary estimate of the prevalence of nephrolithiasis in men and women globally?
A
Men: 10–12%
Women: 7–8%
2
Q
How is renal colic characterized in terms of emergency department (ED) presentations?
A
It is one of the most frequent and expensive ED presentations.
3
Q
In a study comparing renal colic management patterns in two Canadian cities, what were the observed admission and surgical intervention rates?
A
Admission rates: As high as 60%
Surgical intervention rates: Over 50%
4
Q
How did early intervention for renal colic impact subsequent ED visits, re-admissions, and secondary procedures?
A
Early intervention led to increased subsequent ED visits, re-admissions, and secondary procedures.
5
Q
What were the findings regarding costs associated with the management of acute renal colic in terms of non-surgical management?
A
An initial trial of non-surgical management was associated with lower indirect costs.
6
Q
What is the primary objective of the Canadian Urological Association (CUA) guideline document on ureteral calculi?
A
To provide evidence-based consensus recommendations on various aspects relevant to the management of ureteral stones.
7
Q
List the major topic areas included in the CUA guideline document on the management of ureteral stones.
A
Conservative management
Medical expulsive therapy
Shockwave lithotripsy (SWL)
Ureteroscopy (URS)
Special clinical scenarios (e.g., pregnancy, pediatrics)
8
Q
What percentage of symptomatic ureteral stones <4 mm pass spontaneously according to the 2010 meta-analysis?
A
38–71%
9
Q
In placebo-controlled RCTs evaluating medical expulsive therapy (MET), what are the spontaneous passage rates for stones <10 mm?
A
40–80%
10
Q
What is the recommended approach when faced with a suspected “septic stone”?
A
Early goal-directed therapy, including blood and urine cultures, broad-spectrum IV antibiotics, resuscitation, and source control. Decompression of obstructed pyelonephritis is critical.
11
Q
In a prospective trial with patients having a fever >38°C, leukocytosis, and an obstructing stone <15 mm, what were the two methods of decompression compared, and what was the outcome?
A
Ureteric stent and nephrostomy tube (NT). No differences in clinical outcomes were observed.
12
Q
After initial treatment for obstructed system decompression and infection treatment, how long is recommended to wait before definitive treatment?
A
A minimum of seven days.
13
Q
What percentage of patients with renal colic present with acute kidney injury (AKI)?
A
Approximately 6%.
14
Q
According to one RCT, how did early ureteroscopic management compare to delayed intervention in terms of postoperative stenting rates?
A
Early management led to similar stone-free and complication rates but lower rates of postoperative stenting.
15
Q
In RCTs comparing early vs. delayed shock wave lithotripsy (SWL), what benefits were observed for early SWL?
A
Earlier time to stone-free status, fewer required treatments, and possibly lower complications.
16
Q
What is the general recommendation for managing patients with smaller ureteral stones (<5 mm)?
A
Many can initially be managed non-operatively due to high spontaneous passage rates, but close follow-up is necessary.
17
Q
What is the recommended management for obstructive pyelonephritis?
A
Early goal-directed therapy, with timely decompression in either an antegrade or retrograde fashion, depending on the most expedient method.
18
Q
What has been the increase in the use of CT scans for diagnosing urolithiasis in the acute setting in recent years?
A
Over 10-fold.
19
Q
What percentage of acute urolithiasis diagnoses are performed using CT scans and ultrasonography respectively?
A
CT scans are used in 90% of the cases, while ultrasonography is used in less than 7%.
20
Q
How might patient gender affect the initial imaging modality selected for urolithiasis?
A
There is evidence suggesting that patient gender may impact the initial imaging modality chosen.
21
Q
Between ultrasonography and non-contrast CT imaging for renal colic presentations in the ED, which is recommended and why?
A
Ultrasonography is recommended due to the lack of radiation exposure.
22
Q
What is a drawback of point-of-care ultrasonography (POCUS) compared to ultrasonographies performed by radiologists?
A
POCUS is more operator-dependent, and consulting teams often don’t have images or a formal report to review.
23
Q
How does supplementing ultrasonography with KUB X-rays affect the detection of a ureteral stone?
A
It enhances the sensitivity, with results showing sensitivity ranging from 79–100% and specificity up to 100%.
24
Q
What advantage does obtaining a KUB X-ray during diagnostic imaging in the ED offer?
A
It’s useful for determining stone composition and tracking the progress of stone passage in follow-up.
25
How do reduced-dose NCCT scans perform in terms of sensitivity and specificity?
They maintain sensitivities and specificities from 90–97%.
26
How does body mass index (BMI) affect the diagnostic accuracy and radiation doses of CT scans when assessing for stones?
BMI has shown to be less of a concern, with >95% diagnostic accuracy and radiation doses <3.7 mGy regardless of BMI.
27
In the acute setting, what is the added benefit of dual-energy CT scans?
There's little additional benefit as obstructing stones are not typically treated with dissolution therapy, even though dual-energy CT scans can identify uric acid stone composition.
28
What factors should be considered when ordering imaging for non-life-threatening indications?
The patient’s age, pregnancy status, stone history, and preceding exposure to ionizing radiation.
29
What is the CUA's recommendation for the initial modality of choice for acute ureteral stones?
Ultrasonography with KUB X-ray should be considered the initial modality of choice. Judicious use of CT scans, preferably low-dose, is also valuable for management decisions. The utility of a KUB X-ray at the time of presentation is crucial for future follow-up and decision-making regarding treatment options.
30
What is the outcome of recent RCTs regarding the use of alpha-blockers for MET in terms of stone passage rates or reduced analgesic requirements?
Recent RCTs failed to show improved stone passage rates or reduced analgesic requirements when using alpha-blockers for MET.
31
What subgroup of ureteral stones might benefit from MET according to subgroup analysis data?
The benefit might be mainly for larger (5–10 mm), distal ureteral stones.
32
What did higher-quality, placebo-controlled studies in the Cochrane review indicate about MET?
They showed a benefit with MET, a decrease in hospitalizations, and no significant changes in the need for intervention.
33
What is the shift in analgesic preference for patients with renal colic?
There's a move away from opioids towards non-opiate analgesia for these patients.
34
How did NSAIDs compare to morphine in reducing pain for acute care patients in one study?
NSAIDs were more effective in reducing pain by 50% compared to morphine after 30 minutes, with no adverse events.
35
What was the outcome of using non-opioid analgesia regarding opioid requirements during initial presentation?
Protocolled non-opioid analgesia could reduce opioid requirements if first- and second-line interventions included NSAIDS and intravenous lidocaine. However, opioid-sparing approaches were associated with higher rates of repeat visits to the ED.
36
Why should forced IV hydration solely for the purpose of stone passage be avoided?
It's not supported by the literature and should be avoided.
37
What does the recommendation state about the role of MET for ureteral stones?
The role of MET in promoting spontaneous passage is controversial. If there's any benefit, it is for larger (5–10 mm) ureteral (distal) stones. The advantages and disadvantages of MET should be discussed with the patient in a shared decision-making process.
38
What is the recommendation regarding analgesic regimens for renal colic?
The use of opioid-sparing analgesic regimens has been shown to be efficacious. Opioids for the management of renal colic should be minimized, and patient education is paramount.
39
What is the recommendation regarding forced IV hydration for stone expulsion?
Forced IV hydration for the purposes of stone expulsion is not recommended.
40
What percentage of patients reported passage of a symptomatic ureteral stone but still had persistent obstruction on follow-up CT scan imaging?
6.2%
41
How sensitive and specific was the resolution of pain for successful passage of a ureteral stone based on follow-up US and KUB X-ray imaging?
79.7% sensitive and 55.8% specific
42
Why is follow-up imaging suggested after reports of successful passage of obstructing ureteral stones?
Because neither resolution of symptoms nor patient reports always confirm the successful passage of obstructing ureteral stones.
43
How many patients with a persistent ureteral stone confirmed on ultra-low-dose CT lacked hydronephrosis on CT and a visible stone on the CT scout image?
38%
44
Approximately how long will the majority of patients take to spontaneously pass ureteral stones after presentation?
One month
45
List factors associated with an increased risk of chronic kidney disease.
List factors associated with an increased risk of chronic kidney disease.
46
True or False: Resolution of symptoms and patient-reported stone passage always confirm the passage of an obstructing ureteral stone.
False
47
What is the recommendation regarding the duration of conservative management for a ureteral stone?
The recommended duration of conservative management is unique to each patient, considering multiple factors. Surgical intervention should likely be considered if a patient hasn't passed an obstructing ureteral stone after 4–6 weeks.
48
What remains a first-line treatment option for ureteral calculi despite advances in ureteroscopes and laser technologies?
Shockwave lithotripsy (SWL)
49
True or False: The majority of the data for SWL outcomes comes from patients with ureteric stones.
False. Most data comes from patients with renal calculi.
50
Which stone location is most similar to renal calculi when considering the shockwave path during SWL?
Upper ureter.
51
Which stone compositions are most resistant to SWL?
Cystine, pure calcium oxalate monohydrate, and brushite.
52
What is the significance of uric acid stones in the context of SWL?
While they are fragile in the face of SWL, they require either the use of ultrasound or pyelography (intravenous or retrograde) for targeting during SWL.
53
How does stone density, measured in Hounsfield units (HU), relate to SWL outcomes?
There's a linear relationship between increased stone density and poor stone fragmentation. Stones with a density above 1000 HU are less likely to be successfully fragmented.
54
What novel predictor of SWL success has been reported that may outperform HU?
Variation coefficient of stone density (VCSD).
55
What has a longer Skin-to-stone distance (SSD) been associated with in the context of SWL?
Reduced treatment success for both renal and ureteral stones.
56
What SSD value is often associated with decreased stone-free rates (SFRs)?
Greater than 10 cm.
57
Which stones are likely best treated with URS instead of SWL?
Known uric acid, cystine, and brushite stones.
58
What characteristics of ureteral stones indicate lower SFRs with SWL?
A density greater than 1000 HU or an SSD greater than 10 cm.
59
What is the recommendation level for treating uric acid, cystine, and brushite stones with URS?
Level 4, moderate recommendation.
60
What is the recommendation level for shared decision-making with patients regarding stones with a density greater than 1000 HU or an SSD greater than 10 cm?
Level 2, strong recommendation.
61
What is the primary composition of brushite stones?
Brushite (calcium monohydrogen phosphate dihydrate).
62
In what pH range is urine typically when brushite stones form?
Acidic to neutral.
63
How do the hardness and treatability of brushite stones with SWL compare to most other urinary stones?
Brushite stones are harder and more resistant to treatment with SWL.
64
Why are brushite stones clinically significant in the realm of urology?
They are harder, leading to challenges in treatment, and patients with brushite stones have a higher rate of stone recurrence.
65
What medical condition can sometimes be associated with brushite stone formation?
Primary hyperparathyroidism.
66
What factors in the urine can lead to the formation of brushite stones?
Typically acidic to neutral pH, high urinary supersaturation with respect to calcium and phosphate, and reduced levels of urinary inhibitors like citrate.
67
Given their characteristics, which treatment modality might be preferred for brushite stones over SWL?
Ureteroscopic management.
68
What is the primary purpose of gradually increasing SWL energy up to the optimal dose?
Gradual increase in SWL energy allows for better patient accommodation to the sensation of treatment and, for upper ureteral stones, reduces renal injury by inducing renal vasoconstriction.
69
What is an alternative strategy to dose escalation in SWL?
Pre-treating with a series of low-energy shocks, then pausing treatment for a short period of time before resuming at higher-energy levels.
70
After how many unsuccessful SWL treatments is the incremental benefit considered small for the same ureteric stone?
The incremental benefit of more than two treatments for the same ureteric stone is small.
71
What is the unclear optimal time interval between SWL treatments for mid and distal ureteral stones?
2–3 days.
72
For stones larger than 1 cm, what shock rate has been suggested to improve stone fragmentation?
SWL at 60–90 shocks/minute leads to better fragmentation than 120 shocks/minute.
73
What is the recommended shock rate range for upper ureteral stones?
The recommended shock rate range is 2000–3500, but manufacturer’s guidelines should be closely considered.
74
What is the safe shock rate for mid to distal ureteric stones?
For mid to distal ureteric stones, treatment can safely be carried out up to 4000 or more shocks.
75
What are the recommendations for patients with upper ureteric stones in terms of energy, repetition, shock rate, and number of shocks?
Initially receive low-energy shocks with gradual voltage escalation up to maximum energy.
If unsuccessful, repeat SWL can be considered but more than two treatments to the same ureteric stone has little incremental benefit and URS should then be considered.
For stones >1 cm or those selected for retreatment after initial failed SWL, treat at a rate <120 shocks/minute for optimal fragmentation.
Administer an adequate number of shocks (2000–4000 for most lithotripters) to ensure adequate treatment of ureteric stones. A higher number of shocks may result in improved SFRs, but data is limited for a routine practice recommendation.
76
What medication class, most commonly represented by tamsulosin, has been studied for its impact on SWL outcomes?
Alpha-blockers.
77
What are the benefits of alpha-blockers in relation to SWL outcomes based on meta-analyses?
Improved SWL success rates, reduced time to stone passage, decreased risk of steinstrasse, and reduced need for auxiliary procedures.
78
What did the Cochrane systematic review conclude about routine alpha-blocker therapy concerning SWL?
Routine alpha-blocker therapy may result in improved stone clearance, fewer major adverse events, reduced stone clearance time, less need for auxiliary treatments, and potential benefits related to pain and analgesic use.
79
Is routine pre-SWL stenting necessary to improve the success rate or passage of fragments?
No, routine pre-SWL stenting is not necessary and does not improve the success rate or passage of fragments.
80
How might having a stent impact the passage of fragments following SWL?
Having a stent may impede the passage of fragments following SWL.
81
Do stents decrease the risk of steinstrasse or infection post-SWL?
No, stents do not appear to decrease the risk of steinstrasse or infection post-SWL, with a potential exception for stones >2 cm.
82
In which situations might stents be beneficial prior to SWL?
Stents may be beneficial for obstructing stones if relief of obstruction is warranted prior to treatment (such as obstruction with infection, renal failure, intolerable pain) and prior to SWL for stones in a solitary kidney.
83
Based on the recommendation, should alpha-blockers be prescribed after SWL for ureteral stones?
Yes, alpha-blockers (e.g., tamsulosin) should be prescribed after SWL for ureteral stones to improve treatment success rates.
84
What's the recommendation regarding ureteral stents post-SWL for stones <2 cm?
Ureteral stents do not improve SFRs after SWL and do not reduce the risk of steinstrasse or infection following SWL for most patients (i.e., stones <2 cm).
85
What is the significance of modern URS in the treatment of ureteral stones?
Modern URS is a mainstay in the surgical treatment of ureteral stones worldwide. It can be safely performed with high stone-free rates (SFR) and relatively low complications due to advancements in technology.
86
How does the use of preoperative alpha-blockers impact URS outcomes?
Preoperative alpha-blockers improve intraoperative outcomes and patient SFR. They reduce the need for ureteral dilatation by 61%, improve SFR, reduce operative time by six minutes on average, and decrease patient hospital stay.
87
What were the findings of the systematic review and meta-analysis regarding alpha-blocker use before planned URS?
The review comprised 12 RCTs and 1352 patients. With a median preoperative use of one week, a 61% risk reduction in the need for ureteral dilatation was observed. Preoperative alpha-blockers significantly improved SFR (RR 1.18, 95% CI 1.11–1.24, p<0.00001), reduced operative time, and decreased patient hospital stay.
88
Is one week the optimal duration for preoperative alpha-blocker use before URS?
It's uncertain. One week of use might be convenient for patients, but larger RCTs are needed to provide further direction on the efficacy and optimal duration of preoperative alpha-blockers for URS of ureteral stones.
89
What is the purpose of postoperative imaging after URS?
The goal is to assess for residual stone burden and screen for ongoing obstruction. Residual stone fragments can lead to additional stone-related episodes and surgical interventions.
90
What are some reasons against routine postoperative upper tract imaging after uncomplicated URS?
In uncomplicated URS, some authors believe routine postoperative upper tract imaging isn't necessary. They recommend it only for chronic stone impaction, significant ureteral trauma, prior renal impairment, endoscopic evidence of stricture, and postoperative pain or fever.
91
What is silent obstruction and its rate of occurrence post-URS?
Silent obstruction is described as asymptomatic, persistent, postoperative obstructive hydronephrosis. It has been shown to occur at a rate of 1.9–10% following URS.
92
How long is the estimated interval from URS to possible development of ureteral stricture?
The mean interval is estimated to be 13 months.
93
Why isn't NCCT routinely used post-URS?
While NCCT is the best modality for identifying both residual fragments and postoperative obstruction, the effective dosage of radiation and the cost of this modality have prevented its routine use post-URS.
94
What is the recommended postoperative imaging modality following URS for ureteral stones?
An ultrasound (US) ± KUB X-ray is recommended. In complicated cases, further imaging with NCCT can be performed.
95
What are the advantages of using Ureteral Access Sheaths (UAS) during Ureteroscopy?
Allows rapid and multiple re-entries into the upper tract.
Potentially reduces damage to the ureteroscope.
Enhances visibility.
Decreases intrarenal pressure.
Facilitates drainage and elimination of dust and stone fragments.
96
Why is the proper selection of UAS size crucial during URS?
It's crucial to balancing URS outcomes and ensuring that excessive force is not applied, which can lead to complications.
97
In the cohort analysis of 2239 patients, what was the difference in Stone Free Rates (SFR) between UAS use and non-use during flexible URS?
No significant difference. SFR was 75.3% with UAS vs. 50.4% without UAS (p=0.604).
98
For stones ≥10 mm, how did SFRs compare between the UAS group and the non-UAS group?
SFRs were significantly higher in the UAS group: 84.9% vs. 81.5% (p<0.01).
99
What are the reported grades of ureteral injuries related to UAS use?
Low-grade injuries involving the mucosa in almost half of the patients.
High-grade lesions involving the smooth muscle layer in 15% of patients.
100
Do endoscopically detected high-grade ureteral lesions following UAS insertion result in an increased rate of stricture?
No, they do not appear to result in an increased rate of stricture.
101
What is the recommendation regarding UAS use for ureteral stones based on current evidence?
UAS use has no significant impact on SFR nor on intraoperative complications (level 2, moderate recommendation).
UAS may improve visualization, reduce intra-renal pressures, and facilitate fragment removal (level 4, strong recommendation).
102
What can ureteral stent placement prior to elective URS facilitate?
Ureteral stent placement can facilitate UAS and ureteroscope insertion.
103
In a recent study, in what percentage of cases was the ureter inaccessible, necessitating ureteral stent placement?
8% of cases.
104
What has been the impact of routine pre-URS stenting on SFR for larger stones in some studies?
Some studies have shown that routine pre-URS stenting was associated with a higher SFR for larger stones.
105
What scenarios make routine post-URS stent placement advisable?
Suspected ureteric injury or stricture, solitary kidney, and patients with renal impairment.
106
Are urinary symptoms better or worse with stent use post-URS?
Urinary symptoms have been demonstrated to be significantly worse with stent use.
107
Which medications have shown beneficial effects in ameliorating stent-related urinary symptoms?
Alpha-blockers, anticholinergics, and B-agonists.
108
In an animal model, how long post-UAS insertion were there no histological ischemic changes in the ureteral wall?
72 hours, suggesting that three days may be sufficient.
109
What did Paul et al find regarding ureteral stent dwell times of three vs. seven days?
Removal at three days was linked to a higher probability of obstruction-related adverse events (23% vs. 3%).
110
What is the recommendation regarding routine pre-URS stenting?
Routine pre-URS stenting is not necessary but may facilitate UAS insertion and improve SFRs in patients with larger stones (level 2, weak recommendation).
111
What is the recommendation regarding stent placement after UAS use?
Stent placement after UAS use is warranted (level 3, weak recommendation).
112
How can stent-related symptoms following URS be ameliorated?
Stent-related symptoms following URS may be ameliorated with alpha-blocker and/or anticholinergic medications (level 2, moderate recommendation).
113
What is the safest option if access to the ureteral stone is complicated or impossible?
If access to the ureteral stone is complicated or impossible, placement of a stent and repeat URS is the safest option (level 5, strong recommendation).
114
What does SWL stand for in the context of ureteral calculi treatment?
Shock Wave Lithotripsy.
115
What does URS stand for in the context of ureteral calculi treatment?
Ureteroscopy.
116
For upper ureteric stones less than 2 cm, what were the stone-free rates (SFR) for URS vs. SWL at three months, based on a randomized trial?
URS: 86.6%, SWL: 82.2%.
117
Between SWL and URS for upper ureteric stones, which treatment had a significantly higher re-treatment rate?
SWL.
118
When substratified by stone size, which treatment produced a higher SFR for stones measuring 1–2 cm?
URS with an SFR of 85.4% vs. SWL's 78.4%, though the difference wasn't statistically significant.
119
For distal ureteral stones, which treatment has been traditionally considered superior: SWL or URS?
URS.
120
What did a systematic review published in 2017 conclude about the SFR of URS vs. SWL at four weeks and three months?
Better SFR with URS at four weeks, but comparable between both groups at three months.
121
Between URS and SWL, which one required fewer re-treatments for distal ureteral stones but had higher complication rates?
URS.
122
Regarding radiation doses to patients, how did the radiation used for ureteral stones compare between URS and SWL treatments?
Equal amounts of radiation were used for both treatments.
123
In the context of cost-efficacy, under what conditions was URS found to be more cost-effective in the American system for ureteral stones ≤1.5 cm?
When the SFR for SWL was <60–64% or if the chance of URS success was >57–76%.
124
According to the British NICE guidelines, for ureteral stones <1 cm, which treatment was found to be more costly even if the efficacy of the other was only 40%?
URS.
125
What is the CUA's recommendation regarding SWL vs. URS based on efficacy and cost?
SWL produces similar SFR to URS for ureteral stones, albeit with a higher retreatment rate and lower complication rate. While considering local/regional cost models, SWL may be a more cost-effective option for ureteric stones.
126
What is the impact of ureteral stones on health-related quality of life (HRQOL)?
Ureteral stones significantly impact the HRQOL of patients.
127
How often are patients with ureteral stones satisfied with their treatment choice, regardless of the modality (SWL vs. URS)?
Approximately 50% of the time.
128
In a study examining distal ureteric calculi, what percentage of patients were satisfied with URS compared to SWL?
URS: 94.2% (n=113), SWL: 80.4% (n=74).
129
What are the main HRQOL outcomes affected by SWL and URS?
Physical functioning, social functioning, and pain domains on the 36-item Short Form Health Survey (SF-36).
130
Why did patients who received URS score worse on HRQOL compared to those who received SWL?
Due to higher analgesic requirements and longer hospital stays after URS, mainly attributed to the use of a ureteral stent.
131
How long did the improved HRQOL for SWL over URS persist?
It persisted at six months of follow-up, despite the higher stone-free rate (SFR) with URS.
132
How did patients with proximal ureteral stones >10 mm who underwent SWL score on their SF-36?
They scored significantly lower on their SF-36.
133
According to the systematic review, how do URS and SWL impact SF-36 results?
URS and SWL both significantly impact SF-36 results similarly.
134
What is the recommendation regarding patient satisfaction between SWL and URS for the treatment of ureteric calculi?
Overall, there is similar patient satisfaction between SWL and URS for the treatment of ureteric calculi. However, SWL has slightly better HRQOL outcomes, primarily due to the avoidance of a ureteral stent.
135
Risk of peri-renal hematomas and hemorrhagic complications in patients with uncorrected coagulopathies undergoing SWL compared to those with a normal bleeding profile?
20- to 40-fold increased risk.
136
What needs to be corrected and what therapy should be withheld around the time of SWL in patients with coagulopathies?
Bleeding coagulopathies need to be corrected, and anticoagulation therapy should be withheld.
137
How should patients with an increased risk of thromboembolic disease be managed if oral anticoagulation is held?
They should be managed by bridging therapy.
138
What were the independent predictors of renal hematoma in the retrospective study of patients on ASA or LMWH undergoing SWL?
Continued use of ASA and a therapeutic dose of LMWH.
139
What does recent URS technology allow patients with coagulopathies to safely undergo?
URS and laser lithotripsy while anticoagulated.
140
What are the associated outcomes of undergoing URS while anticoagulated?
Lower SFRs and increased risk of postoperative gross hematuria necessitating admission and bladder irrigation.
141
What is the result of using a UAS during URS for patients on anticoagulants?
No increased risk of hemorrhagic complications.
142
Are SWL and antegrade URS recommended for patients with uncorrected coagulopathies?
No, they are contraindicated.
143
What is the recommendation when the risk of holding antiplatelet or anticoagulants outweigh the benefits?
Proceeding with URS while a patient is anticoagulated is an acceptable option (level 2, moderate recommendation).
144
When can Antegrade URS be considered as a treatment option for ureteral stones?
Patients with a urinary diversion when SWL or retrograde access isn't feasible.
Select cases with large, impacted proximal ureteral stones.
When performed alongside renal stone removal.
After a failed retrograde URS attempt for a large, impacted proximal ureteral stone.
When the ureteral stone is in a transplant kidney.
145
What's the primary challenge when dealing with stones in patients with urinary diversions?
Navigating the anatomical changes, which necessitate accurate preoperative assessment using NCCT.
146
When might flexible retrograde URS be a preferable option over antegrade URS for patients with urinary diversions?
When the ureter is accessible through a retrograde approach, like an ileal conduit. This is because antegrade URS has higher rates of postoperative fever/sepsis and higher rates of second-look nephroscopy in these patients compared to those with normal anatomy.
147
For large (>15 mm), impacted, proximal ureteral stones, what is the Stone Free Rate (SFR) with antegrade URS?
The SFR ranges from 98.5–100%, with a low risk for complications.
148
What are the disadvantages associated with the antegrade approach for managing ureteral stones?
The antegrade approach is linked to longer fluoroscopy time, longer procedural time, and a prolonged hospital stay.
149
The antegrade approach is linked to longer fluoroscopy time, longer procedural time, and a prolonged hospital stay.
It should be considered for patients with urinary diversion and select large, impacted, proximal ureteral stones, especially when a prior retrograde URS has failed.
150
How has the incidence of pediatric urolithiasis changed in recent years?
It has increased approximately 4–10% annually in the last two decades.
151
What is the primary concern regarding imaging modalities in children?
Concerns regarding radiation exposure.
152
Which imaging modality is the first-line for suspected renal colic in children?
Ultrasound (US).
153
What are the sensitivity issues of US for urolithiasis in children?
Sensitivity issues, particularly for mid-ureteral calculi.
154
How can the diagnostic accuracy of US be improved in children?
Addition of conventional radiography (KUB X-ray).
155
Which imaging modality has the highest sensitivity and specificity for urolithiasis in children?
Non-Contrast CT (NCCT).
156
How does ultra-low-dose NCCT compare to KUB X-ray in terms of radiation exposure?
It can mitigate radiation exposure to levels similar to KUB X-ray while maintaining diagnostic performance.
157
What is the first-line management for children with urolithiasis <5 mm?
A trial of passage of at least two weeks.
158
What is preferred in children for urgent urinary drainage?
Ureteral stent insertion.
159
How effective and safe is MET in children?
Evidence suggests MET in children may be effective and safe.
160
For children with mid to distal urolithiasis, which procedure is recommended as first-line management?
Ureteroscopy (URS) as it's superior to SWL.
161
For children with proximal ureteral stones, how do SWL and URS compare?
Both SWL and URS have similar Stone-Free Rates (SFRs) and can be considered first-line options.
162
How do complication rates for pediatric SWL compare to adults?
They are similar to adults.
163
What is the complication rate range for pediatric URS?
3.7–20.5%.
164
What are the reported rates of ureteral injury, ureteric stricture, and ureteral avulsion in pediatric URS?
Ureteral injury (2.1–2.8%), ureteric stricture (0.2–1.0%), and ureteral avulsion (0.4%).
165
What factors are most linked with complications in pediatric URS?
Age/size of the child and equipment size.
166
Which size of ureteroscope is recommended for children in general and for children <3 years old?
Ureteroscopes <8 French for general pediatric patients and mini 4.5 French ureteroscopes for children <3 years old.
167
Is routine pre-stenting recommended prior to URS in children?
No, data does not support this.
168
How does the rate of failed retrograde access in children compare to adults?
It's more common in children (30–70%).
169
In cases of failed retrograde access, what approach is preferable?
Pre-stenting and repeat URS after passive dilation.
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How should postoperative stenting be approached in children?
At the discretion of the attending physician, with similar indications as in adults.
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How should children be followed postoperatively after intervention for urolithiasis?
With an US and KUB X-ray 4–6 weeks after the procedure.
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What's the recurrence rate of urolithiasis in the pediatric population after their first episode?
Ranges from 19–50% over a followup of 2–3 years.
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What is the recommendation regarding the first-line diagnostic modality for children with suspected ureteral stones?
Ultrasound, possibly coupled with a KUB X-ray. Low-dose NCCT may be used in certain situations (level 3, strong recommendation).
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What is the recommendation for children with smaller (<5 mm) stones?
A trial of passage with/without MET (level 2, strong recommendation).
175
What is the recommendation regarding ureteral dilation in children?
If needed, passive dilation is preferred (level 4, moderate recommendation).
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What size of ureteroscope is recommended for URS in children?
Ureteroscopes <8 French (level 4, moderate recommendation).
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What type of evidence exists regarding the treatment of ureteral stones during pregnancy?
No level 1 evidence exists. Guidance is primarily from retrospective case series.
178
What is the first recommended diagnostic test for suspected nephrolithiasis during pregnancy?
Ultrasound (US) – abdominal ± transvaginal – due to the lack of radiation.
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If US is non-diagnostic during the first trimester of pregnancy, which imaging can be considered?
Magnetic resonance imaging (MRI). If available, an MRU with a T2-weighted HASTE is preferred for improved accuracy.
180
Which diagnostic methods may be considered in the second and third trimesters?
Ultra-low/low-dose non-contrast computed tomography (NCCT).
181
What is the primary management approach for most ureteral stones during pregnancy?
Most stones will pass spontaneously. The first option is conservative therapy, including hydration and analgesia.
182
Which pain management medication should be avoided during pregnancy for ureteral stones?
NSAIDs due to known fetal risks.
183
How are alpha-blockers categorized and should they be used during pregnancy for ureteral stones?
They are category B-rated. They can be used with caution as an off-label adjunct, although their efficacy is not well-established.
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What are immediate causes for intervention in pregnant women with ureteral stones?
Same as non-pregnant situations, plus induction of premature labor (contractions, fetal distress).
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What are the immediate intervention methods for ureteral stones in pregnancy?
Nephrostomy tube (NT) or ureteral stent insertion.
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How often do ureteral stents and NTs need to be changed in pregnancy?
Every 4–6 weeks due to risk of accelerated encrustation.
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Can ureteroscopy (URS) with laser lithotripsy be used during pregnancy?
Yes, it's shown to be feasible and safe. If imaging is inconclusive and low-dose NCCT or MRI is unavailable, URS can be used for both diagnostic and therapeutic purposes.
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When was URS traditionally recommended to be undertaken during pregnancy?
During the second trimester. However, recent literature suggests there is no evidence to support a “safest” trimester.
189
What precautions should be taken if using X-ray fluoroscopy during URS or stent insertion in pregnancy?
A lead apron or shield should be placed between the X-ray source and the fetus. Alternatively, procedures can be performed under US guidance to avoid radiation.
190
Is shock wave lithotripsy (SWL) recommended during pregnancy?
No, SWL is contraindicated during pregnancy.
191
What is the recommendation for antegrade URS during pregnancy?
It should likely be delayed until after birth due to concerns over prolonged anesthesia and radiation exposure.
192
What is the general recommendation for diagnostic testing for stones in pregnancy?
First-line is US, but low-dose NCCT or MRI (without gadolinium in the first trimester) can also be used.
193
How should obstructing ureteral stones be managed during pregnancy if there's no urinary infection?
Conservatively. If there are signs of sepsis, antibiotics and urinary decompression via NT or stent are critical, and consultation with obstetrics is recommended.
