Editing Stones: Treatment Selection for Upper Urinary Tract Calculi

'''See [[AUA: Stone Surgery (2016)|2016 AUA Stone Surgery Guideline Notes]]'''

Includes 2016 AUA Stone Surgery Guidelines

==Investigations Prior to Treatment[https://pubmed.ncbi.nlm.nih.gov/27238616/ ★]==
===UrologySchool.com Summary===
*'''<span style="color:#ff0000">History and Physical Exam</span>'''
* '''<span style="color:#ff0000">Labs:</span>'''
**'''<span style="color:#ff0000">Mandatory (1):</span>''' 
**#'''<span style="color:#ff0000">Urinalysis +/- culture</span>'''
**'''<span style="color:#ff0000">Certain situations (4):</span>''' 
**#'''<span style="color:#ff0000">Serum electrolytes</span>'''
**#'''<span style="color:#ff0000">Serum creatinine</span>'''
**#'''<span style="color:#ff0000">CBC</span>'''
**#'''<span style="color:#ff0000">Coagulation profile</span>'''
*'''<span style="color:#ff0000">Imaging</span>'''
**'''<span style="color:#ff0000">Non-contrast CT</span>'''
***'''<span style="color:#ff0000">Should be obtained prior to PCNL</span>'''
***'''<span style="color:#ff0000">Can help select between SWL vs. URS (decision should not be based on US)</span>'''
**'''Certain situations: functional imaging, other contrast enhanced studies'''
=== Laboratory===
*'''<span style="color:#ff0000">Urinalysis</span>''' '''+/- culture'''
**'''<span style="color:#ff0000">Required prior to intervention</span>'''
**'''<span style="color:#ff0000">Urine culture'''
***'''Should be obtained in patients with clinical or laboratory signs of infection'''
****If the culture demonstrates infection, appropriate antibiotics should be prescribed based on sensitivity
****'''<span style="color:#ff0000">Intraoperative urine cultures should be obtained, if technically feasible, from urine proximal to the stone if infected urine is suspected at the time of intervention</span>'''
*****'''Potential for discordance between preoperative voided urine cultures or those from indwelling urethral catheters compared to urine proximal to an obstructing stone'''
***'''<span style="color:#ff0000">Stone cultures'''
****'''May be obtained, especially in cases of suspected infection-related stones, in order to help guide postoperative therapy'''
*****'''Potential for discordance between stone cultures and preoperative voided urine cultures'''
**'''<span style="color:#ff0000">Presence of crystals''' 
***May reveal clues to underlying stone composition
** '''<span style="color:#ff0000">Urine pH''' 
***May add useful information when one is considering uric acid stones (low pH) or the presence of urease-producing bacteria (high pH)

*'''<span style="color:#ff0000">Serum electrolytes and creatinine</span>'''
**'''<span style="color:#ff0000">Should be obtained if there is suspicion of reduced renal function</span>'''
***Reduced renal function is suspected in those with hydronephrosis, parenchymal thinning or co-morbid conditions associated with renal dysfunction and electrolyte disturbances
* '''<span style="color:#ff0000">CBC and platelet count</span>'''
**'''<span style="color:#ff0000">Should be obtained for patients:</span>'''
**#'''<span style="color:#ff0000">Undergoing procedures where there is a significant risk of hemorrhage</span>''' (e.g. PCNL)
**#'''<span style="color:#ff0000">With symptoms suggesting anemia, thrombocytopenia, or infection</span>'''
*'''<span style="color:#ff0000">Coagulation studies</span>'''
**'''<span style="color:#ff0000">In the absence of clinical indications</span>''' (e.g., systemic anticoagulation, relevant hepatic dysfunction, hematologic disease or bleeding disorders, history suggestive of a coagulation disorder) '''<span style="color:#ff0000">coagulation studies should not be routinely obtained prior to surgical management of urinary stone disease</span>'''

===Imaging ===
*'''<span style="color:#ff0000">Non-contrast CT</span>'''
**CT protocols have been developed and evaluated utilizing radiation doses approximating those of plain film radiography.
**'''<span style="color:#ff0000">Should be obtained prior to performing PCNL</span>'''
***Defines stone burden and distribution
***Provides information regarding collecting system anatomy, position of peri-renal structures and relevant anatomic variants
***May be used to predict stone composition
***May be used to predict operative outcomes
**'''<span style="color:#ff0000">May be used to help select the best candidate for SWL vs. URS</span>'''
***'''Ultrasound alone to select SWL vs. URS''' '''should be discouraged'''
****'''Disadvantages of US:'''
*****'''Provides no information on stone density'''
*****'''Inaccurate in determination of stone size'''
******US will correlate approximately 2/3 of the time with the stone size determined on CT scan.
******* '''<span style="color:#ff0000">US will overestimate the size of 1/3 of stones < 10 mm, and underestimate the size of 1/3 of stone, > 10 mm.</span>'''
*******'''<span style="color:#ff0000">KUB underestimates > 90% stones > 10 mm due in part to its inability to measure in three dimensions</span>'''
*** '''Factors associated worse SWL outcomes:'''
****'''Renal stone attenuation >900-1000 Hounsfield units'''
****'''Skin-to-stone distance >10cm'''
*'''<span style="color:#ff0000">Functional imaging study (DTPA or MAG‐3)</span>'''
** '''<span style="color:#ff0000">May be obtained if clinically significant loss of renal function in the involved kidney(s) is suspected</span>'''
*'''Additional contrast imaging may be obtained if further definition of the anatomy is needed'''
**'''Situations in which complex urinary tract anatomy may require further imaging include:'''
***'''Ectopic kidneys''' (e.g., horseshoe kidney, pelvic kidney, cross-fused ectopia)
***'''Other congenital kidney conditions''' (e.g., UPJ obstruction, duplicated collecting system, caliceal diverticulum, ureteral stricture, megaureter, ureterocele),
***'''Renal transplant grafts'''
***'''Kidneys with prior surgery'''
***'''Complex stone anatomy/conditions''' (e.g., staghorn stones, nephrocalcinosis).
**Further imaging may be required in certain patients (e.g., neurologic disorders, including spinal dysraphism; unusual body habitus; presence of urinary diversion or prior kidney/ureteral surgery)
**'''<span style="color:#ff0000">CT and IVP are the most useful IV contrast studies</span>'''
***'''MR urography can be useful in defining anatomy during pregnancy (without contrast) and in the setting of IV contrast allergy, although stones are typically not well visualized directly with MR imaging'''
***Contrast imaging studies can also include retrograde or antegrade pyelography
== Treatment Selection ==
* '''<span style="color:#ff0000">Factors to consider when selecting treatment for urolithiasis:</span>'''
*# '''<span style="color:#ff0000">Presence of symptoms</span>'''
*#* '''<span style="color:#ff0000">Observation may be appropriate for select, asymptomatic stones</span>'''
*# '''<span style="color:#ff0000">Stone factors</span>'''
*## '''<span style="color:#ff0000">Total stone burden</span>'''
*## '''<span style="color:#ff0000">Stone location</span>'''
*## '''<span style="color:#ff0000">Stone composition</span>'''
*# '''<span style="color:#ff0000">Patient factors</span>'''
*## '''<span style="color:#ff0000">Anticoagulation</span>'''
*##'''<span style="color:#ff0000">BMI</span>'''
*## '''<span style="color:#ff0000">Renal function</span>'''
*## '''<span style="color:#ff0000">Renal anatomic factors</span>'''

=== General Considerations ===
* '''If purulent urine is encountered during endoscopic intervention, stone removal procedures should be aborted, appropriate drainage should be established,''' antibiotics continued, and a urine culture should be obtained.
* '''Stone material should be sent for analysis'''
** An exception would be a patient who has had multiple recurrent stones that have been documented to be of similar stone composition and there is no clinical or radiographic evidence that stone composition has changed.
== Management of Ureteric Stones ==
===UrologySchool.com summary[https://pubmed.ncbi.nlm.nih.gov/27238616/ ★] ===
*'''<span style="color:#ff0000">Uncomplicated, < 10mm: observation +/- MET (recommended distal, optional mid or proximal location)</span>'''
*'''<span style="color:#ff0000">>10mm or failure of conservative management: URS vs. SWL</span>'''
** '''<span style="color:#ff0000">URS preferred for distal and mid</span>'''
**'''URS and SWL options for proximal'''
===Symptomatic===

==== Conservative treatment ====
*'''<span style="color:#ff0000">If the ureter is not otherwise obstructed (e.g. from ureteric stricture distal to stone), the main determinant of stone passage is the axial diameter of the stone</span>'''
** '''<span style="color:#ff0000">Second most important determinant is the location of the stone within the ureter at presentation</span>'''
** Other factors that may influence interval to stone passage include:
*** Laterality (right side more likely to pass)
*** Duration of symptoms before presentation
*** Degree of hydronephrosis
** Stone composition has not been shown to influence interval to stone passage

===== Observation =====
*'''<span style="color:#ff0000">Patients with uncomplicated [any location] ureteral stones <10 mm should be offered observation; </span>[different than 2015 CUA Ureteric Calculi guidelines which suggest intervention for stone >5mm][https://pubmed.ncbi.nlm.nih.gov/27238616/ ★]'''
**A trial of spontaneous passage is reasonable in patients amenable to conservative therapy with distal ureteral stones <10 mm in whom pain is well controlled and there are no signs of infection or high-grade obstruction.
***'''The smaller the stone and the more distally in the ureter the stone is located, the greater the likelihood of spontaneous passage'''
***'''The control arms of RCTs evaluating tamsulosin as MET show that ≈50% of patients with distal ureteral calculi <10 mm in size will spontaneously pass their stones'''

===== Medical expulsive therapy =====
*'''<span style="color:#ff0000">Patients with uncomplicated distal ureteral stones <10mm should be offered medical expulsive therapy (MET) with α-blockers </span>[same as 2015 CUA Ureteric Calculi Guidelines][https://pubmed.ncbi.nlm.nih.gov/27238616/ ★]'''
**Ureteral contractility is mediated by both α and β adrenoreceptors in the ureteral wall. Stimulation of α1-receptors promotes contraction of ureteral smooth muscle, leading to more vigorous and frequent peristalsis. α1-antagonists have the potential to inhibit ureteral spasm and uncontrolled contraction, theoretically reducing pain and promoting spontaneous stone passage.
***'''In patients with <10 mm distal ureteral stones, spontaneous stone passage rates improves with α-blockers compared to no treatment (ARR: 23%, 77% α-blockers vs. 54% placebo or no treatment)'''
****'''<span style="color:#ff00ff">SUSPEND (Lancet 2015)'''
*****Population: 1136 patients with ≤10 mm ureteral calculi
*****Randomized to tamsulosin (0.4 mg daily), nifedipine (30 mg daily) and placebo (1:1:1)
*****Primary outcome: absence of need for additional intervention at 4 weeks rather than radiographic evidence of stone passage
*****Results: no difference between groups for the primary outcome. 
******The results of this trial were not incorporated into the AUA Guideline Panel’s meta-analysis
****[https://pubmed.ncbi.nlm.nih.gov/25998582/ Pickard, Robert, et al. "Medical expulsive therapy in adults with ureteric colic: a multicentre, randomised, placebo-controlled trial." The Lancet 386.9991 (2015): 341-349.]
**Calcium channel blockers
*** Suppress smooth muscle contraction by inhibiting the influx of extracellular calcium into smooth muscle cells
***Insufficient supporting data for the utilization of this agent for MET.
**Patients should be informed that '''medications for MET are prescribed off-label''' 
*'''<span style="color:#ff0000">MET can be considered an option in patients with an uncomplicated middle or proximal ureteric calculi <10mm; [2015 CUA Ureteric Calculi Guidelines do not explicitly describe role of MET in these locations][https://pubmed.ncbi.nlm.nih.gov/27238616/ ★]'''
**'''No benefit of therapy based on the few α-blocker trials that included patients with middle and proximal ureteral calculi'''; therefore, use of MET for stones in the middle and proximal ureter could not be specifically endorsed. However, because of the low side effect profile of α-blockers and the demonstrated efficacy of α-blockers in patients with <10 mm stones in any location of the ureter, a trial of α-blockers in a patient with middle or proximal ureteric calculi <10mm, can be considered an option, despite the lack of demonstrable benefit

===== Failure of Conservative Treatment =====
*'''<span style="color:#ff0000">In most patients, definitive stone treatment should be offered if observation +/- MET is not successful after 4-6 weeks and/or the patient/clinician decide to intervene sooner[https://pubmed.ncbi.nlm.nih.gov/27238616/ ★]</span>'''
**'''<span style="color:#ff0000">Indications to proceed with surgical intervention (3):</span>'''
**#'''<span style="color:#ff0000">Pain</span>''': recurrent renal colic requiring repeated visits to the emergency department or hospital admission for parenteral analgesia
**#'''<span style="color:#ff0000">Worsening renal function</span>'''
**#'''<span style="color:#ff0000">Infection:</span>''' evidence of urinary tract sepsis
**A 6-week interval is recommended to reduce the potential for permanent damage. 
***'''Continued renal blockage after this time may lead to irreversible kidney damage'''
***A previous study has also indicated that most stones destined to pass spontaneously will do so within 6 weeks. As such, there seems little benefit in continuing MET beyond this time interval.
*'''Clinicians should offer reimaging to patients prior to surgery if passage of stones is suspected or if stone movement will change management'''
**≈10% risk of negative URS for ureteral stones < 4 mm in a distal ureteral location
**'''Other factors that influence the decision to re-image a patient include time interval since prior imaging, pain, and presence of obstruction/hydronephrosis'''
** Reimaging should focus on the region of interest and limit radiation exposure to uninvolved regions
====Intervention====
* '''<span style="color:#ff0000">Approach: URS vs. SWL for ureteric calculi</span>'''
**'''The patient should be informed of the advantages and disadvantages of SWL and URS''' (anesthesia requirements, stone-free rates, need for additional procedures, and associated complications of each procedure)
***'''SWL is the procedure with the least morbidity and lowest complication rate'''
****2012 Cochrane Review comparing SWL and URS identified 7 RCTs '''significantly lower complication rate for SWL compared to URS'''
*****'''Ureteral perforation occurs significantly more frequently during URS than SWL'''
***** '''No difference with regard to UTI, sepsis, ureteral stricture, or ureteral avulsion'''
***'''URS has a greater stone-free rate in a single procedure'''
**** '''Stone-free rates are higher for URS than SWL for all ureteral stones EXCEPT proximal ureteral stones >10 mm in size where stone-free rates are comparable'''
***'''Ureteroscopy is the most cost-effective treatment strategy for ureteral stones at all locations, after observation fails.'''
***'''Patients should be informed about the possible need for stent placement after URS, and less commonly, after SWL, because this may influence their decisions'''
**'''<span style="color:#ff0000">Stone location</span>'''
***'''<span style="color:#ff0000">Mid or distal ureter:[https://pubmed.ncbi.nlm.nih.gov/27238616/ ★]</span>'''
****'''<span style="color:#ff0000">URS is the recommended first-line therapy</span>'''
****'''<span style="color:#ff0000">SWL is second-line therapy</span>'''
*****'''For women of child-bearing age with mid or distal ureteral calculi, URS is preferred, as the effects of shock wave energy on the ovary have not been completely elucidated'''
***'''<span style="color:#ff0000">[Proximal ureter:][https://pubmed.ncbi.nlm.nih.gov/27238616/ ★]</span>'''
****'''<span style="color:#ff0000">[URS and SWL are options</span>''']
*****'''For proximal ureteric stones < 10mm, stone-free rates with URS are superior than SWL'''
*****'''For proximal ureteric stones >10mm, stone-free rates are equivalanet'''
*****'''Therefore, the recommendation for first-line use of URS was not extended to proximal ureteral stones.'''
***Alternative treatment options, such as open or laparoscopic ureterolithotomy, or antegrade URS via a percutaneous approach, are not preferred over SWL because of greater invasiveness.
**'''<span style="color:#ff0000">Stone Composition</span>'''
***'''<span style="color:#ff0000">URS recommended over SWL for suspected cystine or uric acid ureteral stones</span>'''
****'''Cystine stones are often only faintly radio-opaque and pure uric acid stones are typically radiolucent and therefore, stone targeting with fluoroscopy may be problematic for SWL.''' 
****'''Furthermore, cystine stones are typically resistant to SWL fragmentation'''
**'''In patients who fail or are unlikely to have successful results with SWL and/or URS, clinicians may offer PCNL, laparoscopic, open, or robotic assisted stone removal.'''
***A percutaneous and antegrade approach may be used for very large proximal ureteral calculi not amenable to SWL or URS
*** '''If a ureteric stricture is present, can perform open, laparoscopic, or robotic-assisted laparoscopic treatment for both the stricture and the stone in the same session'''

== Management of Renal Stones ==
=== UrologySchool.com Summary[https://pubmed.ncbi.nlm.nih.gov/27238616/ ★]===
*'''<span style="color:#ff0000">Asymptomatic, non-obstructing caliceal stones: active surveillance</span>'''
*'''<span style="color:#ff0000">Symptomatic, total stone burden < 20mm</span>'''
**'''<span style="color:#ff0000">Non-lower pole: either SWL or URS</span>''' are preferred over PCNL
**'''<span style="color:#ff0000">Lower pole:</span>'''
***'''<span style="color:#ff0000">≤10mm: SWL or URS</span>'''
***'''<span style="color:#ff0000">10-20mm: PCNL (first-line) or URS (no SWL)</span>'''
*'''<span style="color:#ff0000">Symptomatic, total stone burden >20mm: PCNL (first-line) or URS (option) (no SWL)</span>'''
[[File:2019auastonesxpathway.jpg|center|734x734px|2019 AUA Guideline Algorithm of Selecting Surgical Treatment of Stones|alt=2019 AUA Guideline Algorithm of Selecting Surgical Treatment of Stones|thumb]]

===Asymptomatic, non-obstructing caliceal stones ===
*'''<span style="color:#ff0000">Active surveillance may be offered'''
** Observation of asymptomatic, non-obstructing caliceal stones is appropriate as long as the patient is counseled about the risk of stone growth, passage, and pain.
**'''There is conflicting data on the natural history of asymptomatic renal stones'''
***'''≈50% of asymptomatic stones will progress, a much smaller percentage will require surgical intervention.'''
****Lower pole stone location and isolated stone ≥ 4 mm were associated with a higher likelihood of failing observation.
****'''Risk of surgical intervention for initially asymptomatic stones: ≈10-20%''' '''at 3-4 years'''
*****'''<span style="color:#ff00ff">Sorenson et al. NEJM 2022</span>[https://pubmed.ncbi.nlm.nih.gov/35947709/]'''
******'''Population: 73 patients,'''  urology clinics of the participating large, urban, tertiary-care centers, '''scheduled to undergo endoscopic surgical treatment (ureteroscopy or PCNL) of a primary stone,''' '''with one or more secondary stones''' on computed tomography (CT)
*******'''Primary stones defined as those located within the ureter or a kidney and that produced symptoms or were considered at high risk of causing an adverse clinical event'''
*******'''Secondary stones defined as small (≤6 mm), asymptomatic renal stones that were:'''
********'''Located in the contralateral kidney (in the case of a primary renal stone) OR''' 
********'''In either kidney (in the case of a primary ureteral stone, with the specific kidney identified before randomization)'''
*******Patients with known systemic disease or anatomical disorders such as medullary sponge kidney, primary hyperparathyroidism, renal tubular acidosis, sarcoidosis, and horseshoe kidney were excluded.
******'''Randomized to treatment vs. control of secondary stones'''
*******'''Secondary stones in patients in the treatment group were removed by ureteroscopy'''
******'''Outcomes'''
*******'''Primary: relapse in each group, defined according to any of 3 measures:'''
*******#'''Emergency department visit owing to stones on the same side where the original asymptomatic stone had occurred (trial side) during the follow-up period (2 weeks to 5 years after surgery)'''
*******#'''Subsequent surgery to remove stones on the trial side in the follow-up period'''
*******#'''Growth of an original secondary stone, as measured with the use of CT.'''
*******#*Stone growth defined as an increase in stone size of more than 1 mm in one dimension or 1 mm or more in two dimensions, as measured by subsequent CT scans.
******'''Results'''
*******Baseline characteristics
********Median secondary stone size: 3 mm treatment vs. 4 mm control
********Median number of secondary stones: 1 treatment vs 1 control
*******'''Primary outcome'''
********'''Treatment group had significantly fewer relapses than the treatment group (relapse rate 16% treatment vs. 63% control)'''
******[https://pubmed.ncbi.nlm.nih.gov/35947709/ Sorensen, Mathew D., et al.] "Removal of small, asymptomatic kidney stones and incidence of relapse." ''New England Journal of Medicine'' 387.6 (2022): 506-513.
*'''Treatment of asymptomatic, non-obstructing renal stones should be considered in:'''
*#'''Solitary kidney (including renal transplants)'''
*#'''Women considering pregnancy'''
*#'''Cases of associated infection'''
*#'''Vocational reasons (e.g. airline pilots, military)'''
*#'''Poor access to medical care'''
*#'''Children'''
*#'''Rapidly increasing in size'''
*If observation is chosen for asymptomatic, non-obstructing caliceal stones, '''follow-up imaging studies to assess for stone growth or new stone formation is recommended'''. Dietary modifications and medical therapy may be considered, especially if new stone formation occurs

=== Symptomatic ===
*'''<span style="color:#ff0000">Treatment approach based primarily on</span>''' 
**'''<span style="color:#ff0000">Total stone burden (most important factor influencing treatment decisions)</span>'''
***'''<span style="color:#ff0000">Classified as (3):</span>'''
***#'''<span style="color:#ff0000">< 1 cm</span>'''
***#'''<span style="color:#ff0000">≥ 1 and ≤ 2 cm</span>'''
***#'''<span style="color:#ff0000">> 2 cm</span>'''
**'''<span style="color:#ff0000">Stone location is second most important consideration</span>'''
***'''<span style="color:#ff0000">Classified as (2):</span>'''
***#'''<span style="color:#ff0000">Lower pole stones</span>'''
***#'''<span style="color:#ff0000">Non-lower pole stones</span>'''

===== <span style="color:#ff0000">Stone burden ≤20mm[https://pubmed.ncbi.nlm.nih.gov/27238616/ ★]</span> =====
*'''<span style="color:#ff0000">Non-lower pole stone</span>'''
** '''<span style="color:#ff0000">Recommended options: SWL or URS</span>'''
***Treatment options for patients with a <20 mm non-lower pole renal stone burden include 
***#SWL
***#URS
***#PCNL
***For stone burdens <20mm, stone-free rates of both URS and SWL are acceptable and have less morbidity compared to PCNL.
****Stones in a non-lower pole location tend to respond more readily to SWL and URS, making those techniques more competitive with PCNL.
****PCNL stone-free rates are the least affected by stone size, while stone-free rates of both SWL and URS decline with increasing stone burden. 
***Excellent clearance with URS has been reported for all renal stones, suggesting that stone size and density, along with patient anatomy, are more important factors than intrarenal stone location when considering URS treatment decisions
***'''For PCNL, stones within the middle calyx and renal pelvis are more likely to be cleared than stones in upper or lower calyceal locations'''
***SWL for kidney stone burden < 1cm
****Stone-free rates: ≈50-90%
***** Most studies have assessed stone-free outcomes using renal ultrasound or plain radiography, which have limited sensitivity to detect small stones
***** '''Successful clearance with SWL is dependent on stone location:'''
******'''Highest for stones in the renal pelvis and ureteropelvic junction''' (UPJ 80-88%)
******'''Favorable for stones in the upper and middle calyces''' (70%)
******'''Consistently less for lower poles stones''' (35-69%)
*'''<span style="color:#ff0000">Lower pole stone</span>'''
**'''<span style="color:#ff0000">≤ 10 mm</span>'''
***'''<span style="color:#ff0000">Recommended options: SWL or URS'''
****An RCT found that there was no significant difference between the stone-free rates with URS vs. SWL. Intraoperative complications were higher with URS, and patient-derived QoL measures were better with SWL in this trial.[https://pubmed.ncbi.nlm.nih.gov/24220692/ §]
**** '''CT imaging parameters should be used for patient selection.'''
****'''<span style="color:#ff0000">Lower pole anatomic features that may reduce stone passage after SWL</span>'''
****# '''<span style="color:#ff0000">Narrow lower pole infundibulum (width <4 mm)</span>'''
****# '''<span style="color:#ff0000">Acute lower pole infundibulopelvic angle (<90 degrees)</span>'''
****# '''<span style="color:#ff0000">Multiple lower pole infundibula rather than a single infundibulum</span>'''
****'''<span style="color:#ff0000">Invasiveness and higher rate of significant complications of PCNL limit its widespread adoption in the treatment of kidney stone burden <1 cm</span>'''
***** PCNL should be used for stones that have failed less invasive treatment modalities (SWL or URS) or are extremely large or dense.
**'''<span style="color:#ff0000">> 10mm</span>'''
***'''<span style="color:#ff0000">Recommended options: PCNL (preferred) or URS; SWL not recommended'''
****'''<span style="color:#ff0000">PCNL has a higher stone-free rate but greater morbidity than URS</span>'''
****'''PCNL should be considered the primary treatment'''
*****Lower pole stones tend to prove the most difficult to treat and are more difficult to clear with URS or SWL, and therefore stones ≥1 cm within the lower pole may be most efficiently treated with PCNL. '''</span>'''
***** PCNL is also preferred when prior URS or SWL attempts have been unsuccessful.
******Ureteroscopy is the treatment modality of choice when PCNL is completely or relatively contraindicated and is a reasonable first-line option in experienced hands'''.'''
**** '''<span style="color:#ff0000">SWL should not be recommended as an initial treatment modality</span>'''
***** In general, SWL results are disappointing for lower pole stone burdens ≥ 1 cm

===== <span style="color:#ff0000">Stone burden > 20 mm [https://pubmed.ncbi.nlm.nih.gov/27238616/ ★]</span>=====
*'''<span style="color:#ff0000">Recommended options: PCNL (first-line) or URS (option); SWL not recommended as first-line</span>'''
**PCNL offers a considerably higher stone-free rate in a single procedure than URS or SWL.
***Success of SWL is dependent on several other factors, including obesity, skin-to-stone distance, collecting system anatomy, stone composition and stone density/attenuation, which could also contribute to lower stone-free rates
***The benefit of a higher stone-free rate must be weighed against the increased invasiveness and risk of complications for PCNL compared to URS or SWL.
****In patients with significant comorbidities or contraindications to PCNL are present (frailty, coagulopathy, refusal of transfusion), less invasive alternatives such as URS, though less efficient and potentially requiring multiple stages, should be considered.
****15% overall complication rate with PNCL, majority categorized as Clavien Grade I. '''Bleeding necessitating blood transfusion (7%) is the most common complication'''
***The risk of ureteral obstruction from stone fragments (steinstrasse) increases
==== Special Scenarios ====

===== Stone composition =====
* '''<span style="color:#ff0000">Affects success rates with SWL; URS, PCNL, and laparoscopic and open stone surgery are less affected by stone composition, if at all.</span>'''
** Therefore, factoring stone composition into treatment decision analysis is most relevant for stones ≤2 cm or less in size, for which SWL is often considered first-line therapy or as a first-line therapeutic option.
** '''<span style="color:#ff0000">Stone compositions most resistant to SWL (in descending order) (4):</span>'''
**# '''<span style="color:#ff0000">Cystine</span>'''
**# '''<span style="color:#ff0000">Calcium phosphate (specifically “brushite”)</span>'''
**# '''<span style="color:#ff0000">Calcium oxalate monohydrate</span>'''
**# '''<span style="color:#ff0000">Matrix</span>'''
**#* '''<span style="color:#ff0000">PCNL is the preferred treatment approach for matrix renal stones</span>''' owing to its high success rates and recurrence rates
** In vitro studies have shown that holmium laser lithotripsy fragmentation efficiency is also dependent on stone composition, with the poorest fragmentation seen for the calcium oxalate monohydrate stones and moderate fragmentation seen for uric acid and cystine stones

===== Residual Fragments =====

* '''<span style="color:#ff0000">Endoscopic (URS or PCNL) procedures should be offered, especially if infection stones are suspected.[https://pubmed.ncbi.nlm.nih.gov/27238616/ ★]</span>'''
** '''Untreated struvite stones have a high likelihood of stone growth and recurrent infections'''. These “infection stones” may grow to a large size, often filling a large portion or the entire renal collecting system (i.e., staghorn calculus). '''Such stones may cause persistent infection and chronic obstruction, ultimately leading to severe renal damage with the possibility of life-threatening sepsis'''. Removal of suspected infection stones or infected stone fragments may significantly limit the possibility of further stone growth, recurrent UTI, or renal damage. An endoscopic approach, either URS or PCNL, offers the best chance of complete removal of infection stones.
** Non-surgical treatment with antibiotics, urease inhibitors, and other supportive measures only is not considered a viable alternative except in patients otherwise too ill to tolerate stone removal or when the residual fragments cannot be safely retrieved

===== Patient factors =====

====== Anticoagulation ======

* '''<span style="color:#ff0000">URS may be safely performed in patients with active anticoagulation or antiplatelet therapy.</span>'''

====== Body mass index ======

* '''<span style="color:#ff0000">PCNL and URS stone-free outcomes are independent of the patient’s BMI, whereas SWL success falls with increasing obesity</span>'''

====== Renal function ======
* '''<span style="color:#ff0000">Symptomatic upper tract stones located in renal units with <15% split function (different thresholds in literature) should be considered for nephrectomy</span>, and stone-specific, nephron-sparing treatments should not be pursued.'''
*'''No change in long-term renal function from SWL, multiple URS, or single-access tract PCNL'''
** The effects of multi-access tract PCNL on renal functional outcomes are mixed

===== Renal anatomic factors =====

====== Ureteral pelvic junction obstruction ======
* '''<span style="color:#ff0000">Options to treat renal stones with concomitant UPJO (3):</span>'''
*# '''<span style="color:#ff0000">PCNL with antegrade endopyelotomy</span>'''
*# '''<span style="color:#ff0000">Retrograde endopyelotomy with URS stone removal</span>'''
*# '''<span style="color:#ff0000">Pyeloplasty (laparoscopic or robotic) with pyelolithotomy or nephrolithotomy</span>'''

====== Calyceal diverticula ======
* Calyceal diverticula are urothelium-lined, non-secretory, cystic dilations of the intrarenal collecting system that are thought to arise embryonically.
* '''Associated with poor urine drainage'''
* '''A large percentage of calyceal diverticula are asymptomatic'''
* '''<span style="color:#ff0000">Management</span>'''
** '''<span style="color:#ff0000">Asymptomatic calyceal diverticular stones require no treatment</span>'''
** '''<span style="color:#ff0000">Indications for intervention: calyceal diverticular stones associated with (4):</span>'''
**# '''<span style="color:#ff0000">Pain</span>'''
**# '''<span style="color:#ff0000">Recurrent infections</span>'''
**# '''<span style="color:#ff0000">Hematuria</span>'''
**# '''<span style="color:#ff0000">Decline in renal function</span>'''
** Whether non-obstructing caliceal stones can be a source of pain is controversial.There are published reports of eradication of flank pain with stone removal in this setting. '''The patient must be informed of the possibility that the pain may not improve or resolve after the procedure.[https://pubmed.ncbi.nlm.nih.gov/27238616/ ★]'''
**'''<span style="color:#ff0000">Approach:</span>'''
*** '''<span style="color:#ff0000">Options: PNCL (preferred) vs. URS (no SWL)</span>'''
**** '''Choice depends on both stone and diverticular anatomic characteristics'''
**** '''<span style="color:#ff0000">PCNL should be considered first-line treatment for most calyceal diverticular stones</span>'''
***** '''<span style="color:#ff0000">Directly puncturing into the calyceal diverticulum is preferable</span> and allows for stone fragmentation and removal, easy fulguration of the diverticular lining, and dilation of the diverticular neck if visible and desired'''
****** '''Ablation of the calyceal diverticular lining, dilation of the diverticular neck to improve drainage, or both are considered integral to achieving stone clearance and preventing stone recurrence'''
**** '''URS is a reasonable first-line treatment approach for patients with small (<2 cm) calyceal diverticular stones arising from an upper or middle calyx, and with a diverticular neck that is short and identifiable'''
***** '''<span style="color:#ff0000">For stones in an anterior calyceal diverticulum, URS is preferered over PNCL due to the high risk of bleeding associated with PNCL into an anterior calyx</span>'''
**** '''SWL is seldom successful for diverticular stones and should not be considered first-line therapy for most symptomatic diverticular stones'''

====== Horseshoe Kidneys and Renal Ectopia ======
* '''<span style="color:#ff0000">Horseshoe Kidneys</span>'''
** Embryonically, the abnormal medial fusion of the left and right metanephric blastemata creates an isthmus that anchors the '''fused kidneys at the level of the inferior mesenteric artery''', leading to incomplete renal ascent and malrotation. As a result, the:
**# '''<span style="color:#ff0000">Renal pelvis becomes elongated and anteriorly located</span>'''
**# '''<span style="color:#ff0000">UPJ has a high insertion into the renal pelvis</span> and is also anteriorly situated'''
**# '''<span style="color:#ff0000">Proximal ureter courses more anteriorly</span>''' than usual because it must traverse over the isthmus of the horseshoe kidney.
*** '''<span style="color:#ff0000">Collectively, these changes are thought to impede normal urinary drainage</span> and promote urinary stasis and renal stone formation'''
* '''<span style="color:#ff0000">Management</span>'''
** '''<span style="color:#ff0000">SWL is a reasonable treatment option for stone burden < 1.5 cm and there is no UPJO or demonstration of poor renal drainage</span>'''
*** '''<span style="color:#ff0000">UPJO and poor pelvicalyceal drainage must be excluded before SWL treatment</span>'''
**** '''These are not uncommon in horseshoe kidneys and severely impede SWL success'''
**** '''Pelvic kidneys are routinely malrotated and often have a high ureteral insertion or UPJO, which can further hinder stone fragment passage'''
** '''<span style="color:#ff0000">URS may also be reasonable for stone burden < 2 cm, although they may require multiple treatment sessions.</span>'''
*** '''<span style="color:#ff0000">During URS, fragmented stones should be basket extracted rather than left in situ and left to pass spontaneously, given the often compromised drainage associated with horseshoe kidneys</span>'''
** '''<span style="color:#ff0000">For stone burdens of ≥2 cm, PCNL or laparoscopy should be the initial treatment</span>; a combination of the two procedures is expected for pelvic kidneys'''
*** '''<span style="color:#ff0000">PCNL stone clearance and complications rates are the same for horseshoe kidney compared to orthotopic kidney.</span>'''
**** '''<span style="color:#ff0000">A retroreneal colon may accompany horseshoe kidneys, and a preoperative CT is recommended to fully evaluate the safest percutaneous track.</span>'''
** '''<span style="color:#ff0000">When UPJO is confirmed, laparoscopy is the treatment of choice because it can address the stones and provides the highest success rate for UPJ repair.</span>'''

====== Renal transplants ======
* '''<span style="color:#ff0000">SWL</span>'''
** '''<span style="color:#ff0000">An option for kidney stone burden <1.5 cm in transplant kidneys</span>'''; however, high re-treatment rates and auxiliary procedure rates should be expected
* '''<span style="color:#ff0000">URS</span>'''
** '''<span style="color:#ff0000">Antegrade and retrograde URS can be used</span>''' to treat transplant kidney and ureteral stones.
* '''<span style="color:#ff0000">PCNL</span>'''
** '''<span style="color:#ff0000">The preferred treatment choice for large-burden stones(>1.5 cm)</span>''' or if less invasive methods have failed.
* '''<span style="color:#ff0000">General consensus is to remove upper tract stones within renal transplants, as the consequences of an obstructing stone can be devastating</span>'''
* '''In transplanted kidneys, typical renal colic does not occur because the transplanted kidney and ureter are denervated'''. '''The presentation may instead resemble acute rejection or acute tubular necrosis'''

====== Prior renal surgery ======
* '''Not a contraindication to any form of renal stone surgery.'''
===== Staghorn stones =====
* '''No standard definition exists for complete and partial staghorn stones'''
**'''Most consider complete staghorn stones to occupy the entire renal collecting system, whereas partial staghorn stones occupy less.'''
* Majority of staghorn stones are struvite in composition.
* '''Should be removed if attendant comorbidities do not preclude treatment.[https://pubmed.ncbi.nlm.nih.gov/27238616/ ★]'''
**'''<span style="color:#ff0000">Observation and non-operative management is discouraged</span>'''
***'''<span style="color:#ff0000">Natural history of untreated staghorn stones (3):</span>'''
***# '''<span style="color:#ff0000">Complete loss of function in the affected kidney</span>'''
***#* Complete renal function loss in 50% of affected kidneys can occur after 2 years without treatment
***# '''<span style="color:#ff0000">Recurrent UTIs and sepsis episodes</span>'''
***# '''<span style="color:#ff0000">Increased overall mortality</span>'''
*'''<span style="color:#ff0000">PCNL is the method of choice for treating partial or complete staghorn kidney stones</span>'''
** '''<span style="color:#ff0000">Best approached through upper or lower polar access</span>'''
*'''Poorly or nonfunctioning kidneys and those associated with xanthogranulomatous pyelonephritis may be best managed with nephrectomy'''
* Medical therapy and supportive care are considerations for those not thought to be operative candidates.

==== Open/laparoscopic/robotic nephrolithotomy ====
*'''<span style="color:#ff0000">Should not be offered as first-line therapy to most patients with stones'''
*'''<span style="color:#ff0000">Indications (2):'''
*# '''<span style="color:#ff0000">Rare cases of anatomic abnormalities with large or complex stones'''
*# '''<span style="color:#ff0000">Requiring concomitant reconstruction, such as those with''' '''concomitant UPJ obstruction or ureteral stricture.'''

====Nephrectomy====
*'''<span style="color:#ff0000">Indications'''
**'''<span style="color:#ff0000">May be performed when the involved kidney has negligible function'''
***'''Observation may be appropriate for some asymptomatic patients. However, poorly functioning kidneys can often be a source of persistent infection, pain, and pyelonephritis. In these cases, nephrectomy may be the best treatment option to relieve symptoms and prevent systemic complications, such as sepsis and xanthogranulomatous pyelonephritis.'''
***When considering nephrectomy for the poorly functioning kidney, overall renal function and the condition of the kidney on the contralateral side should be considered.
*'''In pregnant patients, nephrectomy should be avoided, if possible, until after they deliver.'''

== Evaluation of Outcome ==

* '''Comparison of outcomes between endourologic stone treatment types is difficult due to varied definitions of success'''
** Since the introduction of SWL, treatment outcomes for patients with renal calculi have been reported by two different terms: 
***Stone-free rate 
***Success rate
****Success rate includes patients who are stone free as well as those with clinically insignificant residual fragments.
*****'''<span style="color:#ff0000">Definition of clinically insignificant residual fragments (CIRF): fragments between 2-4 mm.</span>'''
** These different methods of reporting treatment results, the lack of a standard definition for CIRF, and the various modalities used for assessing postprocedural stone-free status (KUB studies, nephrotomography, ultrasonography, CT) make the comparison of endourologic stone outcomes difficult

== Questions ==

# What stone burden threshold is considered an indication for PCNL in renal transplant patients?

== Answers ==

# What stone burden threshold is considered an indication for PCNL in renal transplant patients?
#* >1.5 cm

== Next Chapter: [[Stones During Pregnancy]] ==

== References ==

* Wein AJ, Kavoussi LR, Partin AW, Peters CA (eds): CAMPBELL-WALSH UROLOGY, ed 11. Philadelphia, Elsevier, 2015, chap 52
*[https://pubmed.ncbi.nlm.nih.gov/27238616/ Assimos, Dean, et al. "Surgical management of stones: American urological association/endourological society guideline, PART I." ''The Journal of urology'' 196.4 (2016): 1153-1160.]