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Kidney stones in adults: Surgical management of kidney and ureteral stones

Kidney stones in adults: Surgical management of kidney and ureteral stones
Author:
Glenn M Preminger, MD
Section Editor:
Michael P O'Leary, MD, MPH
Deputy Editor:
Albert Q Lam, MD
Literature review current through: Dec 2022. | This topic last updated: Aug 23, 2022.

INTRODUCTION — Kidney stone disease (nephrolithiasis) is a common problem in primary care practice. Approximately 10 to 20 percent of all kidney stones require surgical removal, which is determined based upon the presence of symptoms and the size and location of the stones.

This topic will review the surgical management of kidney and ureteral stones. Medical management and other aspects of kidney stones in adults are discussed separately:

(See "Kidney stones in adults: Epidemiology and risk factors".)

(See "Kidney stones in adults: Diagnosis and acute management of suspected nephrolithiasis".)

(See "Kidney stones in adults: Evaluation of the patient with established stone disease".)

(See "Kidney stones in adults: Prevention of recurrent kidney stones".)

(See "Kidney stones in adults: Kidney stones during pregnancy".)

GENERAL PRINCIPLES

Goals of surgical therapy — The overall goals of surgical stone management are relief of patient discomfort, clearance of infection, and reversal of kidney function impairment associated with kidney or ureteral stones.

Important outcomes that should be discussed with patients when deciding upon surgery include the following:

Treatment success – Treatment success for ureteral or kidney stone surgery is generally defined as complete stone removal, or the stone-free rate (SFR). Although there is no consensus definition for SFR, commonly used definitions include the absence of residual stones or the presence of residual stone fragments ≤4 mm in size as determined by follow-up imaging studies such as kidney ultrasound, plain abdominal imaging, digital tomosynthesis, or low-dose, noncontrast computed tomography (CT). Achieving a stone-free status is important, since small residual stone fragments, particularly those >4 mm, may grow and ultimately result in return visits to the emergency department or require additional surgical intervention (see 'Residual stone fragments and additional surgery' below). Additional important measures of treatment success include the need for retreatment or secondary procedures.

Risk of complications – The benefits of surgical stone removal must be weighed against the risk for morbidity and complications. Procedures that offer the highest SFRs (such as ureteroscopy [URS] and percutaneous nephrolithotomy [PNL]) also have higher complication rates. Complications associated with specific procedures are discussed elsewhere in this topic. (See 'Surgical options' below.)

Quality of life – Following surgical stone removal, patients should expect to experience an improvement in quality of life, such as resolution of pain associated with kidney stones or the prevention of future symptomatic stone episodes. However, quality of life may also be reduced by the use of postoperative ureteral stents (most commonly after URS) that can cause patient discomfort. (See 'Ureteral stent placement' below and 'Stent discomfort' below.)

Indications and contraindications — In general, the main indications for surgical treatment of stones include pain, infection, and urinary tract obstruction. No specific surgical therapy is required for asymptomatic stones, particularly those that are less than 5 mm in diameter. However, surgical stone removal may be reasonable for patients with asymptomatic stones who are frequent travelers or pilots, those considering pregnancy, or those who wish to avoid symptomatic stone episodes that may require emergency surgery. Specific indications for emergency and elective surgery include the following:

Indications for emergency surgery – Urgent decompression of the collecting system is indicated in the following clinical scenarios:

Patients with obstructing stones and suspected or confirmed urinary tract infection (UTI)

Patients with bilateral obstruction and acute kidney injury (AKI)

Patients with unilateral obstruction with AKI in a solitary functioning kidney

Indications for elective surgery – Among adult patients who do not have an emergency indication for surgery, specific indications for surgical stone treatment are provided by the 2016 American Urological Association/Endourological Society guidelines, which recommend surgical management in the following clinical settings [1]:

Ureteral stones >10 mm

Uncomplicated distal ureteral stones ≤10 mm that have not passed after four to six weeks of observation, with or without medical expulsive therapy (MET) – (See "Kidney stones in adults: Diagnosis and acute management of suspected nephrolithiasis", section on 'Medical expulsive therapy'.)

Symptomatic kidney stones in patients without any other etiology for pain

Pregnant patients with ureteral or kidney stones in whom observation has failed

Persistent kidney obstruction related to stones

Recurrent UTI related to stones

Contraindications – There are no absolute contraindications to stone removal surgery. However, shock wave lithotripsy (SWL) should not be performed in patients who are obese, are pregnant, or have an uncontrolled bleeding diathesis.

CHOICE OF SURGICAL APPROACH — The optimal approach to managing kidney and ureteral stones depends upon the size, location, and composition/hardness of the stone. Other patient comorbidities (such as concurrent infection, obesity, bleeding diathesis, or pregnancy) as well as patient preferences may also impact the choice of therapy. (See 'Special patient groups' below.)

Emergency surgery — In patients who require emergency surgery for stone removal, urgent decompression of the collecting system with either percutaneous nephrolithotomy (PNL) or ureteroscopy (URS) with ureteral stenting is indicated [2]. (See 'Indications and contraindications' above.)

Patients with obstructing stones and suspected or confirmed urinary tract infection (UTI) require urgent drainage of the collecting system and antimicrobial therapy; a ureteral stent or percutaneous nephrostomy tube can be used to drain the collecting system. Definitive stone management can proceed once the infection is treated and the patient is stable. Stone manipulation in this setting may lead to life-threatening sepsis and should therefore be avoided. The choice between a ureteral stent or nephrostomy tube may be decided by the operating urologist; both have been shown to be equally effective at drainage in one randomized trial [3].

Support for urgent decompression is provided by a retrospective study of 1712 patients with obstructing ureteral stones and sepsis, of whom 78 percent underwent surgical decompression [2]. Mortality was lower among patients who were treated with surgical decompression compared with those who were not (9 versus 19 percent, respectively), and lack of surgical decompression was independently associated with an increased risk of mortality (odds ratio 2.6, 95% CI 1.9-3.7).

Elective surgery

Ureteral stones — URS and shock wave lithotripsy (SWL) are the most commonly performed surgical modalities for the removal of ureteral stones. In patients who do not require emergency surgery and have indications for elective stone removal (see 'Indications and contraindications' above), the choice of surgical procedure depends primarily upon the size and location of the stones but may also be influenced by other patient characteristics (such as pregnancy, urinary tract anatomy, or stone composition) and comorbidities (eg, obesity, bleeding diathesis). (See 'Special patient groups' below.)

Our approach to the selection of surgical modality, which is largely consistent with the 2016 American Urological Association/Endourological Society and 2018 European Association of Urology guidelines [1,4], is as follows (algorithm 1):

For proximal and mid-ureteral stones that are ≤10 mm, we suggest SWL or URS as first-line therapy, rather than PNL and other surgical options. (See 'Ureteroscopy' below and 'Shock wave lithotripsy' below.)

For proximal and mid-ureteral stones that are >10 mm, we suggest URS as first-line therapy, rather than SWL or other surgical options. (See 'Ureteroscopy' below.)

For all distal ureteral stones, regardless of size, we suggest URS as first-line therapy, rather than SWL or other surgical options. (See 'Ureteroscopy' below and 'Shock wave lithotripsy' below.)

SWL should be avoided in patients with obesity, pregnant patients, patients with an uncontrolled bleeding diathesis, patients with abnormal kidney/ureteral anatomy, and patients whose preoperative imaging with computed tomography (CT) demonstrates high attenuation of the stone (ie, >900 Hounsfield units). (See 'Special patient groups' below.)

In general, PNL and laparoscopic, robot-assisted, and open surgery should not be offered as first-line therapy for most ureteral stones. However, such procedures may be considered for patients in whom SWL and/or URS are unsuccessful, with complex kidney or ureteral anatomy, with large (>20 mm) or complex stones, or requiring concomitant reconstructive surgery for anatomic defects (eg, ureteropelvic junction [UPJ] obstruction or ureteral stricture). (See 'Percutaneous nephrolithotomy' below and 'Other surgical options' below.)

Our approach described above is guided by multiple meta-analyses of randomized trials that have shown that URS, compared with SWL, offers higher stone-free rates (SFRs) and requires fewer retreatments and secondary procedures, but has a higher rate of complications [1,5-8]. A 2016 systematic review that evaluated the efficacy of URS and SWL for the treatment of ureteral stones reported the following findings [1]:

The overall SFR was significantly higher with URS as compared with SWL (90 versus 72 percent).

For stones ≤10 mm, SFRs were superior for URS compared with SWL at all locations in the ureter: 85 versus 67 percent for proximal ureteral stones, 91 versus 75 percent for mid-ureteral stones, and 94 versus 74 percent for distal ureteral stones.

For stones >10 mm, SFRs were comparable between SWL and URS in the proximal ureter (74 versus 79 percent, respectively) but were superior for URS in the middle and distal ureter (83 versus 67 percent for mid-ureteral stones and 92 versus 71 percent for distal ureteral stones).

Rates of UTI, sepsis, ureteral stricture, or ureteral avulsion were comparable between SWL and URS. However, ureteral perforation occurred more frequently with URS than with SWL (3 versus 0 percent). Another meta-analysis also reported higher procedure-related complication rates with URS compared with SWL (16 versus 9 percent) [5].

URS is more likely to successfully treat patients with ureteral stones in a single procedure, reducing the need for additional procedures [9]. In one analysis, the mean numbers of primary URS procedures needed to treat stones in the proximal, middle, and distal ureter were 1.01, 1.00, and 1.00, respectively; by contrast, the corresponding mean numbers of primary SWL procedures were 1.34, 1.29, and 1.26, respectively [9].

Kidney stones — SWL, URS, and PNL are the most commonly used surgical modalities for patients who require removal of kidney stones. In patients who do not require emergency surgery and have indications for elective stone removal (see 'Indications and contraindications' above), the choice of surgical procedure depends primarily upon the size and location of the stones but may also be influenced by other patient characteristics (such as pregnancy, urinary tract anatomy, or stone composition) and comorbidities (eg, obesity, bleeding diathesis). (See 'Special patient groups' below.)

Our approach to the selection of surgical modality, which is largely consistent with the 2016 American Urological Association/Endourological Society and 2018 European Association of Urology guidelines [1,4], is as follows (algorithm 2):

For stones that are ≤15 mm that are in the upper pole, middle calyx, or pelvis of the kidney, we suggest SWL or URS as first-line therapy, rather than PNL or other surgical options. (See 'Shock wave lithotripsy' below and 'Ureteroscopy' below.)

For stones that are ≤15 mm that are in the lower pole of the kidney, we suggest URS or PNL, rather than SWL or other surgical options. (See 'Ureteroscopy' below and 'Percutaneous nephrolithotomy' below.)

For stones that are >15 mm, regardless of location in the kidney, we suggest PNL as first-line therapy, rather than other surgical options. If PNL is not available or contraindicated, staged URS (ie, performed in separate planned sessions) is an alternative option. (See 'Percutaneous nephrolithotomy' below.)

SWL should be avoided in patients with obesity, pregnant patients, patients with an uncontrolled bleeding diathesis, patients with abnormal kidney/ureteral anatomy, and patients whose preoperative imaging with CT demonstrates high attenuation of the stone (ie, >900 Hounsfield units). (See 'Special patient groups' below.)

In general, laparoscopic, robot-assisted, and open surgery should not be offered as first-line therapy for most kidney stones. However, such procedures may be considered for patients in whom SWL, URS, and PNL are unsuccessful, with complex kidney or ureteral anatomy, with large (>20 mm) or complex stones, or requiring concomitant reconstructive surgery for anatomic defects (eg, UPJ obstruction or ureteral stricture). (See 'Other surgical options' below.)

The rationale for our approach is based upon evidence from several randomized trials and meta-analyses [1,10-21]. Collectively, these studies have demonstrated the following findings:

In general, SFRs for both SWL and URS decrease with increasing stone size, whereas the efficacy of PNL is minimally affected by stone size [10].

For stones <20 mm located in upper pole, middle calyx, or pelvis of the kidney, SWL and URS offer SFRs of approximately 50 to 80 percent [10,22]. In one meta-analysis that compared SWL and URS for kidney stones 10 to 20 mm in size, URS provided a higher SFR and lower retreatment rate without an increase in the rate of complications [13].

For stones located in the lower pole of the kidney, particularly those >10 mm, URS and PNL offer substantially higher SFRs compared with SWL, with a moderately increased risk of complications. In one systematic review, for lower pole stones between 10 and 20 mm in size, the median SFR was 81 percent for URS, 87 percent for PNL, and 58 percent for SWL [1]. For lower pole stones >20 mm, the median SFR was 83 percent with URS, 71 percent for PNL, and 10 percent for SWL. In general, although the ability of SWL to disintegrate stones in the lower pole of the kidney is not limited compared with other locations, the fragments frequently remain in the calyx and cause recurrent stone formation.

For stones >20 mm, PNL offers the highest SFRs (approximately 80 to 95 percent for upper and middle pole stones and 70 to 80 percent for lower pole stones).

Special patient groups

Patients with obesity — In patients with obesity (body mass index [BMI] >30 mg/k2), SWL should be avoided, since its efficacy is decreased in such patients [23,24]. URS is less impacted by body habitus and is the preferred method of stone removal in patients with obesity [4,25]. CT imaging parameters may be helpful in decision making. As an example, patients with a skin-to-stone distance greater than 9 to 10 cm are less likely to have a successful treatment with SWL [23,26]. (See 'Preoperative imaging' below.)

Pregnant patients — In pregnant patients who require surgical stone removal, URS is the procedure of choice. SWL and PNL are contraindicated during pregnancy. This is discussed in more detail elsewhere. (See "Kidney stones in adults: Kidney stones during pregnancy", section on 'Management'.)

Patients with bleeding diathesis — In patients with uncorrected bleeding disorders or who require continuous anticoagulation or antiplatelet therapy, URS can usually be safely performed and should be considered first-line therapy [27-29]. SWL and PNL are contraindicated in patients with uncorrected bleeding diatheses. The perioperative management of patients receiving anticoagulants or antiplatelet agents is discussed separately. (See "Perioperative management of patients receiving anticoagulants" and "Perioperative medication management", section on 'Medications affecting hemostasis'.)

Abnormal kidney/ureteral anatomy — Patients with anatomic abnormalities of the kidney or ureter are preferentially treated with endoscopic approaches such as URS or PNL, which may also permit correction of the abnormality [30]. SWL is generally not used in patients with altered kidney or ureteral anatomy. Abnormalities that create obstruction distal to the targeted stone (such as UPJ obstruction, urinary diversion with ureteral anastomotic narrowing, ureteral stricture, and caliceal diverticula) may limit the ability to clear stone fragments when SWL is performed, resulting in lower SFRs [31,32].

Harder stone composition — The composition of the stone, if known from prior stone analysis or suspected based upon CT findings (see 'Preoperative imaging' below), may impact the choice of surgical intervention. Stones of harder composition, such as calcium oxalate monohydrate stones, brushite stones, cystine stones, and homogeneous stones with a high density (>900 Hounsfield units) on noncontrast CT, are less likely to be disintegrated by SWL [33,34]. Such stones are preferentially treated with PNL or URS. (See "Cystinuria and cystine stones".)

Struvite stones — Patients with struvite (infection) stones are preferentially treated with PNL. SWL, with placement of adequate drainage of the kidney prior to the procedure, is an alternative option for patients who have a smaller stone volume and normal collecting system anatomy. The surgical management of struvite stones is discussed in more detail elsewhere. (See "Kidney stones in adults: Struvite (infection) stones", section on 'Choice of surgical approach'.)

PREOPERATIVE EVALUATION

Laboratory testing — Prior to surgery, we obtain a urinalysis in all patients to assess for urinary tract infection (UTI). In patients with signs of infection (eg, presence of leukocyte esterase and nitrite in the urine), we obtain a urine culture and treat as appropriate with culture-specific antimicrobial therapy. Ideally, patients should have a sterile urine prior to stone removal. However, certain stones such as struvite stones are associated with bacteriuria that will not be cleared until the patient is stone free.

The need for additional laboratory testing is guided by the particular surgical procedure to be performed or the presence of other patient comorbidities:

A complete blood count and platelet count should be obtained in patients undergoing PNL [1].

Serum creatinine, blood urea nitrogen (BUN), and electrolytes should be obtained in patients with evidence of hydronephrosis or kidney parenchymal thinning on imaging studies.

Preoperative imaging — In most patients for whom surgical stone treatment is planned, we obtain preoperative imaging with noncontrast computed tomography (CT) of the abdomen and pelvis, if not already performed within the prior three months. A recently obtained noncontrast CT is useful to define stone burden and distribution and provides information regarding collecting system anatomy, the position of structures surrounding the kidney, and relevant anatomic variants. In some cases, the CT can be helpful in predicting stone composition. As an example, stones with higher density on CT (>900 Hounsfield units) are considered to be harder in consistency and may be less amenable to disintegration with SWL. (See "Kidney stones in adults: Diagnosis and acute management of suspected nephrolithiasis", section on 'Noncontrast CT' and "Kidney stones in adults: Diagnosis and acute management of suspected nephrolithiasis", section on 'Determination of stone composition'.)

Additional contrast-enhanced imaging may be required to better define the collecting system and anatomy in patients with complex kidney/ureteral anatomy or complex stones (ie, staghorn calculi). Contrast-enhanced CT, intravenous pyelography (IVP), and occasionally a retrograde pyelogram are the preferred imaging studies for most patients with complex kidney/ureteral anatomy, although magnetic resonance (MR) urography (without contrast) is preferred for pregnant patients or patients with an allergy to intravenous iodinated contrast. Clinical scenarios in which contrast-enhanced imaging may be needed include patients with the following [1]:

Ectopic kidneys (eg, horseshoe kidney, pelvic kidney, cross-fused ectopia)

Congenital kidney disorders (eg, ureteropelvic junction [UPJ] obstruction, duplicated collecting system, caliceal diverticulum, ureteral stricture, megaureter, ureterocele)

Kidney transplant allograft

Kidneys with prior surgery or complex stone anatomy (eg, staghorn stones, nephrocalcinosis)

Neurologic disorders (eg, spinal dysraphism)

Unusual body habitus

Urinary diversion or prior ureteral surgery

SURGICAL OPTIONS — The most commonly used surgical procedures for stone removal are minimally invasive techniques such as shock wave lithotripsy (SWL), ureteroscopy (URS), and percutaneous nephrolithotomy (PNL). Other, less commonly performed, procedures include laparoscopic, robot-assisted, and open surgery. A discussion of these surgical options, including the basic procedure and complications, is presented below.

Shock wave lithotripsy — SWL remains one of the most commonly used procedures for kidney stones worldwide [35]. SWL can be used to treat small- to medium-sized kidney stones but is not the ideal modality for the management of large or complex stones or stones located in the lower pole of the kidney. The dependent location of lower pole stones makes it more difficult for fragments produced by SWL to be cleared from the kidney. In addition, SWL should not be used in patients with obesity, who are pregnant, or with a bleeding diathesis. (See 'Choice of surgical approach' above.)

Procedure – SWL is generally performed on an outpatient basis with the patient under conscious sedation, general anesthesia, or regional anesthesia. SWL employs high-energy shock waves produced by an electrical discharge. The shock waves are transmitted through water and directly focused onto a kidney/ureteral stone with the aid of biplanar fluoroscopy. The change in tissue density between the soft kidney tissue and the hard stone causes a release of energy at the stone surface. This energy fragments the stone. The main limitations of SWL are the completeness of stone fragmentation as well as the completeness of fragment elimination. Alpha blockers (eg, tamsulosin) may be prescribed to facilitate stone passage following SWL.

Complications – In general, SWL has a low complication rate. Up to 5 percent of patients may experience ureteral blockage due to stone fragments (see 'Ureteral obstruction' below), which is usually transient, and up to 2 percent of patients may develop urinary tract infection (UTI) [36]. Transient hematuria is common after the procedure but typically resolves within days. Major complications such as sepsis and hemorrhage are rare and occur in less than 1 percent.

Although there was previously some concern that SWL could cause long-term complications such as hypertension, kidney injury, and infertility, a systematic review found no strong evidence to support an association between SWL and these adverse effects [37].

Ureteroscopy — Although smaller proximal ureteral or kidney stones may be managed by SWL, URS continues to be the treatment of choice for the majority of middle and distal ureteral stones and can also be used to manage proximal ureteral and kidney stones. In addition, URS is frequently useful for the management of ureteral stones that have failed SWL. URS is the modality of choice for patients with obesity, with hard stones, or who are pregnant or have a bleeding diathesis. (See 'Choice of surgical approach' above.)

Procedure – URS is generally performed on an outpatient basis with the patient under general anesthesia. A small endoscope (which may be rigid, semirigid, or flexible) is passed from the urethra proximally toward the affected ureter and kidney, which enables visualization and manipulation of the stone. Flexible ureteroscopes, with their deflection capabilities, are used primarily to access the proximal ureter and intrarenal collecting system [38], while semirigid and rigid ureteroscopes can be used to reach stones in the mid and distal ureter.

Ureteral access and dilation are often the first components of URS. We routinely employ ureteral balloon dilators, which are passed over guidewires that have been fluoroscopically positioned within the kidney collecting system. After dilation of the distal ureter, the ureteroscope can then be passed under direct vision throughout the ureter and renal pelvis. If the obstructing stone is small enough to be extracted intact, stone baskets or grasping forceps can be employed for stone removal. If, however, the stone is too large for intact extraction and requires fragmentation prior to removal, laser fragmentation can be utilized to perform "intracorporeal lithotripsy." Holmium and thulium laser lithotripsy are the technologies of choice to fragment kidney or ureteral stones during URS [39]. A second or third URS procedure (so-called staged URS) may be required to manage large, complex ureteral or kidney calculi.

Stent placement – Stents are sometimes placed after URS, in part to help prevent ureteric obstruction and pain resulting from ureteral edema or passage of a stone fragment. This issue is discussed elsewhere in this topic. (See 'Ureteral stent placement' below.)

Complications – URS is generally considered a safe procedure but has a higher complication rate compared with SWL. The most frequently reported complications with URS include ureteral stent discomfort (more than 25 percent of patients), UTI (5 percent), and ureteral wall injury (5 percent) [40]. Major complications such as sepsis or ureteral avulsion occur in less than 1 percent of patients [41].

Percutaneous nephrolithotomy — PNL is generally considered to be more effective than SWL or URS for most stones. However, because of its higher complication rate compared with SWL and URS, PNL is typically reserved for large or complex stones or when attempts at SWL and URS are unsuccessful. PNL is the procedure of choice for patients with stones >20 mm or staghorn stones [1]. (See 'Choice of surgical approach' above.)

Procedure – PNL is performed with the patient under general anesthesia in the prone or supine position and typically requires an inpatient hospital stay of one to three days. The procedure involves making a small skin incision in the patient's flank region and then placing a hollow working sheath through the incision to the kidney under fluoroscopic or ultrasound guidance. An endoscope is then passed through the working sheath that will enable visualization and extraction of the stone. Laser lithotripsy or lithotripters can be used if necessary to fragment the stone prior to removal. Irrigation with normal saline is usually performed throughout the procedure [1].

Multiple enhancements in PNL techniques and technologies have resulted in smaller access tracts into the kidney (so-called "mini" or "micro" PNL) [42,43]. Mini-PNL utilizes smaller nephroscopes and laser lithotripsy to access and fragment smaller kidney calculi and may provide more efficient kidney stone removal with less patient morbidity (ie, no ureteral stent) than staged URS [44]. In addition, modified patient positions, such as supine or prone split-leg PNL, may also facilitate stone removal [45,46].

Nephrostomy tube placement – Following percutaneous stone removal, an indwelling nephrostomy tube may be left in place to facilitate drainage from the kidney and allow for re-entry into the collecting system should a repeat PNL procedure be necessary for residual stone fragments. However, in patients undergoing uncomplicated PNL who are presumed stone free, placement of a nephrostomy tube may be considered optional. Foregoing the nephrostomy tube at the end of the procedure (ie, "tubeless" PNL) has been shown to be just as safe and effective as the standard approach of leaving a nephrostomy tube in place [1,47-50]. Tubeless PNL also offers advantages such as less pain, less debilitation, lower cost, and a shorter hospital stay [50]. In addition, some studies suggest that an internal ureteral stent does not need to be used with a tubeless PNL. This so-called "tubeless, stentless" PNL procedure offers a further reduction in patient morbidity as the internal stent-related symptoms are avoided [51,52].

Complications – Due to its more invasive nature, PNL has a higher complication rate compared with URS and SWL. However, complication rates are similar to those of open stone surgery. The complications of PNL were described in a large multicenter study that included 5803 patients, of whom 1466 (28 percent) had a staghorn calculus and 940, 956, and 2603 had upper, interpolar, and lower pole stones, respectively [53]. The overall complication rate was 15 percent, with the most common complications being significant bleeding (8 percent), renal pelvis perforation (3 percent), and hydrothorax (2 percent). Procedural complications were more common with larger stones [54].

Infectious complications may also occur after PNL [54,55]. In a large Chinese study, for example, 2.4 percent of patients developed septic shock following the procedure [55].

Other surgical options — Other, less commonly performed, surgical options include laparoscopic, robot-assisted, and open surgery:

Laparoscopic and robot-assisted surgery – Laparoscopic and robot-assisted surgery are alternative surgical options for patients with large or complex kidney stones. They are less invasive than open stone surgery and are associated with less morbidity and shorter recovery periods. However, they are more invasive than SWL, URS, and PNL and are usually reserved for patients in whom these minimally invasive techniques have failed.

Data on the efficacy of laparoscopic and robot-assisted surgery in the treatment of urinary stones are limited [56-58]. Studies suggest that laparoscopic surgery is a reasonable alternative to URS or SWL for large proximal ureteral stones [56,57].

Open surgery – Open surgery is rarely performed and is reserved for the management of complex kidney and ureteral stones that cannot be removed with a reasonable number of minimally invasive procedures. Indications include patients for whom endoscopic stone removal has failed, with complex (staghorn) kidney stones, and with complex kidney/ureteral anatomy or morbid obesity.

PERIOPERATIVE CONSIDERATIONS

Antibiotic prophylaxis — For patients undergoing elective ureteroscopy (URS) or percutaneous nephrolithotomy (PNL), we suggest prophylactic antibiotics to reduce the incidence of postprocedure urinary tract infection (UTI). We administer a single dose of oral or intravenous antibiotics within one hour of the procedure that covers gram-positive and gram-negative microorganisms (table 1) [59]. Choice of antibiotic prophylaxis should also be based upon local antibiotic resistance patterns. This practice is consistent with guidelines from the American Urological Association, European Association of Urology, and others [1,4,59,60]. Antibiotic prophylaxis is not typically administered before shock wave lithotripsy (SWL).

In a systematic review and meta-analysis of four trials (500 patients) evaluating the use of prophylactic antibiotic therapy in patients undergoing URS, a single dose of prophylactic antibiotics reduced postprocedure pyuria (risk ratio [RR] 0.65, 95% CI 0.51-0.82) and bacteriuria (RR 0.26, 95% CI 0.12-0.60) but did not significantly reduce rates of UTI compared with no prophylaxis [61]. An observational study of patients undergoing PNL found that in those with a negative baseline urine culture, antibiotic prophylaxis, compared with no prophylaxis, was associated with a lower rate of postoperative fever (2.5 versus 7.4 percent) and other complications (2 versus 22 percent) [62].

Removal of secondary stones — There is no consensus regarding the management of secondary, asymptomatic kidney stones that are detected on preoperative CT imaging (see 'Preoperative imaging' above). Removing secondary stones, especially on the ipsilateral side of the symptomatic stone removal, to render a patient stone free may help to reduce the risk of stone relapse requiring additional surgery. However, the impact of additional stone removal on surgical time and patient morbidity, especially when considering removal of a contralateral, asymptomatic stone, must be taken into consideration. In our practice, when removing an obstructing or symptomatic stone by URS or PNL, we routinely remove ipsilateral asymptomatic stones during the same procedure since this does not add significant time (approximately 30 to 60 minutes) or morbidity to the procedure. However, we do not routinely remove a symptomatic stone on one side and then remove asymptomatic stones in the contralateral kidney. For patients undergoing URS, this would require bilateral URS and placement of bilateral ureteral stents, which could potentially increase patient morbidity. (See 'Stent discomfort' below.)

Although previous studies have supported an approach of watchful waiting of asymptomatic kidney stones [63-66], data from one randomized trial suggest that simultaneously removing secondary, asymptomatic stones at the time of surgery for a primary, symptomatic stone may be of benefit. In a multicenter trial, 73 adults who were scheduled to undergo endoscopic surgical stone removal for a primary stone and had one or more secondary stones (defined as asymptomatic stones ≤6 mm in the contralateral kidney [in the case of a primary kidney stone] or in either kidney [in the case of a primary ureteral stone]) on CT were randomly assigned to removal of both primary and secondary stones (treatment group) or primary stones alone (control group) [67]. The choice of surgical approach for the primary stone was determined by the urologist (URS or PNL); secondary stones were removed by URS. After a mean of 4.2 years, the risk of relapse was lower in the treatment group compared with the control group (16 versus 63 percent; hazard ratio 0.18, 95% CI 0.07-0.44). Patients in the treatment group had a longer time to relapse than those in the control group (mean time 1631 versus 934 days, respectively). Removal of secondary stones added a median of 25.6 minutes to the total surgery time. Rates of emergency department visits within two weeks of surgery (all for ureteral stent pain), asymptomatic stone or fragment passage, and new stone formation were similar between the groups. Additional studies are needed to demonstrate that the benefit of removing an asymptomatic contralateral stone by URS outweighs the potential morbidity of requiring a second ureteral stent, as bilateral ureteral stenting is a requisite for performing bilateral stone removal.

The management of residual stone fragments is discussed below. (See 'Residual stone fragments and additional surgery' below.)

Ureteral stent placement — Ureteral stents are sometimes placed after URS, in part to help prevent ureteric obstruction and pain resulting from ureteral edema or passage of a stone fragment. However, routine placement of stents after uncomplicated URS should be discouraged. Stent placement is frequently uncomfortable for patients. In three meta-analyses of trials evaluating patients who underwent ureteroscopic lithotripsy, compared with those who did not receive a stent, patients receiving stents had more lower urinary tract symptoms (dysuria, frequency or urgency, and hematuria) [68-70]. (See 'Stent discomfort' below.)

The 2016 American Urological Association guidelines state that ureteral stent placement can be omitted in patients who meet all of the following criteria [1]:

No suspected ureteric injury during URS

No evidence of ureteral stricture or other anatomical impediments to stone fragment clearance

Normal contralateral kidney

No kidney function impairment

No secondary URS procedure planned

In addition, routine placement of a ureteral stent prior to URS (prestenting) is not recommended. Although some clinicians advocate for prestenting prior to URS in order to dilate the ureter and improve stone-free rates (SFRs), we and others believe that the added health care costs and negative impact on quality of life associated with stents outweigh the potential benefits [1].

Routine ureteral stenting should not be performed in patients undergoing SWL. Although stent placement prior to SWL may reduce the accumulation of stone fragments in the ureter (see 'Ureteral obstruction' below), it has not been shown to improve SFRs with SWL compared with no stent placement [1,71].

Stone analysis — Stone material that is retrieved from surgery should be sent for analysis of stone composition. This is discussed in greater detail elsewhere. (See "Kidney stones in adults: Evaluation of the patient with established stone disease", section on 'Stone analysis'.)

POSTOPERATIVE MANAGEMENT

Postoperative imaging — The presence of residual stone fragments after stone removal increases the risk for future clinical stone disease, and therefore, all attempts to render a patient completely stone free should be made. To limit morbidity resulting from undiagnosed residual stone fragments, it is important to properly image patients two to three months following their stone removal procedures [72]. Imaging should determine the presence of residual fragments and assess for possible urinary tract obstruction. In asymptomatic patients, we prefer digital pelvic tomosynthesis (DT) paired with kidney ultrasound to assess for residual stone fragments and obstruction, respectively. If DT is not available, an alternative approach is to obtain an abdominopelvic radiograph paired with ultrasound of the kidneys. For symptomatic patients with or without hydronephrosis or asymptomatic patients with hydronephrosis noted on kidney ultrasound, computed tomography (CT) of the abdomen and pelvis without and with contrast can determine the presence and/or site of obstruction, with further treatment dictated by the findings. (See "Kidney stones in adults: Diagnosis and acute management of suspected nephrolithiasis", section on 'Diagnostic imaging'.)

Medical therapy — The effectiveness of surgical therapies must not overshadow the importance of medical therapy to prevent new stone formation. A treatable metabolic etiology of stone formation can be detected in more than 95 percent of patients evaluated for stone disease. (See "Kidney stones in adults: Epidemiology and risk factors".)

A variety of medical treatments may correct the underlying medical defects responsible for stone formation, thereby reducing the occurrence of new stone formation. Examples for which controlled trials have demonstrated benefit include a high fluid intake for all forms of stone disease, a thiazide diuretic for hypercalciuria, allopurinol or potassium citrate for hyperuricosuria, potassium citrate for hypocitraturia, and potassium citrate for uric acid stone formation due to persistently acid urine. These therapies are discussed in more detail elsewhere. (See "Kidney stones in adults: Prevention of recurrent kidney stones" and "Kidney stones in adults: Uric acid nephrolithiasis", section on 'Treatment'.)

Several randomized trials and observational studies of medical therapy after an initial surgical intervention have demonstrated efficacy in preventing the recurrence of clinical stone disease [73-78]. As examples:

In a study of 100 patients with calcium stones who had residual stone fragments after shock wave lithotripsy (SWL), patients who were randomly allocated to receive hydrochlorothiazide were significantly less likely than those given placebo to have growth of residual stone fragments (18 versus 58 percent) or to require repeat SWL (18 versus 42 percent) [74].

In a second trial, 90 patients with calcium oxalate stones who underwent SWL (approximately one-third of whom had residual stone fragments) were randomly assigned to potassium citrate or no therapy; potassium citrate significantly reduced future clinical stone episodes [76]. The incidence of recurrent clinical stones was also significantly lower among the subset of patients with residual stone fragments (65 versus 78 percent).

After SWL, 70 patients with residual fragments post-SWL (30 with sterile calcium and 40 with struvite stones) were randomly assigned to alkalinization therapy with citrate or to hygienic measures only (such as increased fluid intake and avoidance of excessive intake of dairy products) [75]. Antibiotics were administered to all patients with infected stones. At one year, alkalinization was associated with a greater likelihood of being stone free in patients with calcium stones (74 versus 32 percent) and also in patients with struvite stones (86 versus 40 percent).

Common complications

Stent discomfort — Stent discomfort is common following ureteral stent placement (see 'Ureteral stent placement' above). For patients who receive a ureteral stent, we suggest treatment with an alpha blocker (eg, tamsulosin 0.4 mg daily, until the stent is removed) to reduce stent discomfort. Several randomized, controlled trials and meta-analyses have showed improvements in urinary symptoms, pain, and quality of life with the use of alpha blockers compared with placebo or no treatment [79-82]. Although anti-muscarinic agents have been added to alpha blockers in the past, one randomized, controlled trial found that the addition of tolterodine to tamsulosin, compared with tamsulosin alone, did not improve urinary symptoms or quality of life in patients after ureteral stent placement [83].

Ureteral obstruction — The accumulation of stone fragments or stone gravel in the ureter, known as steinstrasse, occurs in approximately 4 to 7 percent of cases of SWL and may cause ureteral obstruction [84,85]. Larger stone size appears to be the major predictive factor in steinstrasse formation [86]. Patients may be asymptomatic or may present with passing gravel in the urine, flank pain, and/or fever [86]. While SWL of the collection of stone fragments in the ureter or placement of a nephrostomy tube has been recommended in the past, advances in ureteroscopic instrumentation and laser stone fragmentation make ureteroscopy (URS) the initial treatment option for managing patients with steinstrasse.

Urinary tract infection — Urinary tract infection (UTI) may occur following SWL, URS, or percutaneous nephrolithotomy (PNL). A follow-up urinalysis should be performed in all patients following stone removal. We typically obtain a urinalysis at two to three weeks after stone surgery when the patient returns for a postoperative follow-up visit or at any time if the patient is symptomatic. In postoperative patients who are symptomatic, a urine culture should also be obtained, and culture-specific antibiotic therapy should be administered as appropriate.

Residual stone fragments and additional surgery — One of the primary goals of stone surgery is to render patients stone free following SWL, URS, or PNL. Several studies suggest that even small residual stones, particularly those larger than 4 mm, may grow and ultimately result in return visits to the emergency department or require additional surgical intervention [87,88]. The following studies illustrate the range of findings:

Persistent stone fragments are particularly important in patients with struvite (infection) stones. In one series with a mean follow-up of 27 months, 16 of 20 kidneys that were free of stones at three months after SWL remained without stones; by comparison, 14 of 18 kidneys with residual stone particles at three months showed disease progression [89].

In a report of 160 patients with residual, nonstruvite stone fragments smaller than 5 mm in size, the incidence of a symptomatic episode or the requirement for reintervention at two and five years was 43 and 71 percent, respectively [90].

In a retrospective study of 658 patients who underwent PNL and received a postoperative computed tomography (CT) on day 1, 45 percent of patients were found to have residual fragments [91]. Residual stone fragments larger than 4 mm were associated with higher rates of stone-related events and shorter time to recurrence of stone-related events. The growth and spontaneous passage of residual fragments appeared to be independent of fragment size, emphasizing the importance of obtaining a completely stone-free status after PNL.

In a multicenter, retrospective study of 232 patients with residual stone fragments following ureteroscopic stone removal, 56 percent required no further intervention and remained asymptomatic, 15 percent experienced complications requiring no intervention, and 29 percent required intervention [92]. Fragments larger than 4 mm were more likely to grow with time and were associated with more complications.

Given that the presence of residual stone fragments after stone removal increases the risk for future clinical stone disease, all attempts to render a patient completely stone free should be made. Ancillary endoscopic procedures may be necessary to remove residual stone material or relieve urinary tract obstruction, especially in those patients who remain symptomatic. Available evidence suggests that URS is more effective and less morbid than either SWL or PNL in managing small residual stone material [93].

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Kidney stones".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5th to 6th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10th to 12th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

Basics topic (see "Patient education: Hydronephrosis in adults (The Basics)")

Beyond the Basics topic (see "Patient education: Kidney stones in adults (Beyond the Basics)").

SUMMARY AND RECOMMENDATIONS

General principles – The overall goals of surgical stone management are relief of patient discomfort, clearance of infection, and reversal of kidney function impairment associated with kidney or ureteral stones. Important outcomes that should be discussed with patients when deciding upon surgery include treatment success (ie, stone-free rate [SFR]), risk of complications, and quality of life. In general, the main indications for surgical treatment of stones include pain, infection, and urinary tract obstruction. Asymptomatic stones can be removed in certain individuals, such as frequent travelers or pilots or those considering pregnancy. (See 'Goals of surgical therapy' above and 'Indications and contraindications' above.)

Choice of surgical approach – The optimal approach to managing kidney and ureteral stones depends upon the size, location, and composition/hardness of the stone. Other patient comorbidities (such as concurrent infection, obesity, bleeding diathesis, or pregnancy) as well as patient preferences may also influence the choice of therapy:

Emergency surgery – Patients with an infection associated with obstruction of the urinary tract require urgent drainage of the collecting system and antimicrobial therapy; a ureteral stent or a percutaneous nephrostomy tube can be used to drain the collecting system. Definitive stone management can proceed once the infection is treated and the patient is stable. (See 'Emergency surgery' above.)

Elective surgery – Shock wave lithotripsy (SWL), ureteroscopy (URS), and percutaneous nephrolithotomy (PNL) are the most commonly performed surgical modalities for patients who require elective removal of ureteral or kidney stones (algorithm 1 and algorithm 2). (See 'Shock wave lithotripsy' above and 'Ureteroscopy' above and 'Percutaneous nephrolithotomy' above.)

-Ureteral stones – For proximal and mid-ureteral stones that are ≤10 mm, we suggest SWL or URS as first-line therapy, rather than PNL or other surgical options (Grade 2C). For proximal and mid-ureteral stones that are >10 mm, we suggest URS as first-line therapy, rather than SWL or other surgical options (Grade 2C). For all distal ureteral stones, regardless of size, we suggest URS as first-line therapy, rather than SWL or other surgical options (Grade 2C). However, for patients who decline URS, SWL is an alternative option. (See 'Ureteral stones' above.)

-Kidney stones – For stones that are ≤15 mm that are in the upper pole, middle calyx, or pelvis of the kidney, we suggest SWL or URS as first-line therapy, rather than other therapies (Grade 2C). For stones that are ≤15 mm that are in the lower pole of the kidney, we suggest URS or PNL, rather than SWL or other therapies (Grade 2C). For stones that are >15 mm, regardless of location in the kidney, we suggest PNL as first-line therapy, rather than other therapies (Grade 2C). If PNL is not available or contraindicated, staged URS (ie, performed in separate planned sessions) is an alternative option. (See 'Kidney stones' above.)

-SWL should be avoided in patients with obesity, pregnant patients, patients with an uncontrolled bleeding diathesis, patients with abnormal kidney/ureteral anatomy, and patients whose preoperative imaging with computed tomography (CT) demonstrates high attenuation of the stone (ie, >900 Hounsfield units). (See 'Special patient groups' above.)

-In general, laparoscopic, robot-assisted, and open surgery should not be offered as first-line therapy for the most ureteral or kidney stones. However, such procedures may be considered for patients in whom SWL, URS, and PNL are unsuccessful, with complex kidney or ureteral anatomy, with large (>20 mm) or complex stones, or requiring concomitant reconstructive surgery for anatomic defects (eg, ureteropelvic junction [UPJ] obstruction or ureteral stricture). (See 'Other surgical options' above.)

Preoperative evaluation – Prior to surgery, we obtain a urinalysis in all patients to assess for urinary tract infection (UTI). In patients with signs of infection (eg, presence of leukocyte esterase and nitrite in the urine), we obtain a urine culture and treat as appropriate with culture-specific antimicrobial therapy. In most patients for whom surgical stone treatment is planned, we obtain preoperative imaging with noncontrast CT of the abdomen and pelvis, if not already performed within the prior three months. Additional contrast-enhanced imaging may be required to better define the collecting system and anatomy in patients with complex kidney/ureteral anatomy or complex stones (ie, staghorn calculi). (See 'Preoperative evaluation' above.)

Perioperative considerations – For patients undergoing elective URS or PNL, we suggest prophylactic antibiotics to reduce the incidence of postprocedure UTI (Grade 2C). We administer a single dose of oral or intravenous antibiotics within one hour of the procedure that covers gram-positive and gram-negative microorganisms. Ureteral stents are sometimes placed after URS, in part to help prevent ureteric obstruction and pain resulting from ureteral edema or passage of a stone fragment. However, routine placement of stents after uncomplicated URS should be discouraged. (See 'Perioperative considerations' above.)

Postoperative management – Common complications after stone surgery include ureteral stent discomfort, ureteral obstruction (steinstrasse), and UTI. For patients who receive a ureteral stent, we suggest treatment with an alpha blocker to reduce stent discomfort (Grade 2C). The presence of residual stones following SWL or PNL, especially fragments 4 mm or greater, is associated with an increased risk of stone formation or stone growth. Thus, all attempts to render a patient completely stone free should be made. Some patients may require ancillary procedures to remove residual stone material or relieve urinary tract obstruction. (See 'Stent discomfort' above and 'Residual stone fragments and additional surgery' above.)

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