Introduction

Percutaneous nephrolithotomy (PNL) is a common procedure for treatment of large or complex intrarenal stones, with the indications expanding along with improving technology. Currently, the American Urological Association and Endourology Society Surgical Management of Stones Guidelines recommend PNL as first-line therapy for all patients with intrarenal stones > 20 mm or lower pole stones > 10 mm [1]. Despite these recommendations, PNL is still the least commonly utilized technique for nephrolithiasis given the concern for morbidity associated with the procedure. As with any surgical practice, complications can occur, although understanding of the possible outcomes, prompt recognition of such complications, and proper treatment can significantly decrease the risk of long-term morbidity. In this review, complications of PNL will be discussed with a specific focus on their identification and appropriate response.

Bleeding complications

Some of the most common and concerning complications seen in patients undergoing PNL are related to blood loss, either intraoperative or postoperative. Transfusion rates vary widely based on series, but have been documented from 1 to 34% [2,3,4,5,6,7,8,9]. Across differing studies, many factors have been associated with such complications, including surgeon technique and experience, longer operative time, preoperative anemia and diabetes, patient age, increased stone burden, and need for multiple or larger access tracts [6, 8, 10]. Additionally, history of open stone surgery and intraoperative injury (e.g. infundibular or pelvic wall tear) have been associated with increased blood loss as well [9].

Intraoperative bleeding

Preoperative workup is necessary to decrease the bleeding risks associated with this procedure. The AUA recommends performing non-contrast CT scan and complete blood count with platelets prior to percutaneous surgery, both of which can be used to assist in preoperative planning [1]. Perioperative anticoagulation is a complicated situation, although it is generally agreed upon that, when possible, withholding of such medications—including warfarin, anti-platelets, and the anti-Xa medications—is preferred to decrease bleeding risk. Aspirin, which was typically held perioperatively, is now more frequently continued through the perioperative period as recent data demonstrate the safety of performing PNL on this medication [11]. Other anticoagulant medications should be stopped prior to PNL, if possible, although timing of cessation and restarting of these medications should be discussed with the prescribing physician [12]. Alternatively, perioperative removable inferior vena cava filter placement is another option in certain patients who are at high risk of thromboembolic disease [13,14,15].

Surgical technique is a significant modifiable risk factor for bleeding complications. In general, percutaneous access to the renal collecting system should be performed through a posterior calyx along its axis to avoid blood vessels that course alongside the infundibulum [16]. The nephrostomy tract should be dilated only to the edge of the collecting system, as medial dilation increases the risk of renal pelvic injury. Additionally, some studies show that retrograde endoscopically-guided percutaneous access may decrease intraoperative blood loss, possibly by increasing the chances of access through the center of the papilla and direct visualization of tract dilation [17]. Excessive torqueing of rigid instruments should be avoided, with placement of additional access points or the utilization of flexible instruments if the stones cannot easily be reached [18,19,20,21]. Similarly, over manipulation of the sheath can increase bleeding, especially if the sheath is accidently moved out of the collecting system [22, 23].

Tract dilation deserves additional discussion, as there is concern that tract size and dilation method may affect intraoperative and postoperative bleeding risk. Studies have shown contradicting results, including that balloon dilation is safest with regards to bleeding [10, 24], that serial dilation has a lower risk [25], or that dilation method has no effect on bleeding complications [6, 26, 27]. Studies also suggest that a smaller tract size may decrease bleeding risk, although this finding has not been definitively demonstrated [22].

Intraoperative bleeding may be encountered despite proper management of the above concerns. A small amount of bleeding, when it does not obscure the operating field, can often be improved by repositioning of the access sheath into the collecting system. One study noted irrigation with antifibrinolytic agents may decrease bleeding risk, although more data are needed to support this technique [28]. If a larger amount of intraoperative bleeding is noted, the procedure should be stopped, and a 30 French balloon dilator can be inflated within the tract with eventual placement of a large-bore (> 18 French) nephrostomy tube for tamponade [29]. Postoperative clamping of the nephrostomy tube usually resolves the issue if the bleeding is due to a venous injury; administration of mannitol may cause renal swelling to assist in tamponade of bleeding vessels along the nephrostomy tract [6, 30]. Additionally, specialized nephrostomy catheters or other hemostatic catheter-based methods have been developed to manage intraoperative bleeding with good results [31,32,33]. When these methods fail or arterial injury is suspected, renal angiography with angioembolization is prudent.

Given that nephrostomy tube-free PNL (tubeless PNL) is becoming more common, it is important to discuss perioperative hemorrhage risk in these cases, which appears to be on par with standard PNL [34]. It is recommended that in patients with significant intraoperative bleeding, a nephrostomy tube be left for tamponade, but other methods including point cautery within the nephrostomy tract and the use of hemostatic agents have been evaluated [35,36,37]. At this point, the data do not support use of hemostatic agents within the nephrostomy tract; nephrostomy tube placement should be standard in procedures complicated by excessive blood loss.

Postoperative bleeding

Postoperative bleeding risk continues for several weeks after the procedure, with approximately 1% of patients eventually requiring angiographic treatment for this complication [5, 7, 38]. If significant bleeding is noted upon removal of a nephrostomy tube, digital tamponade with eventual fluoroscopy-guided tube replacement is indicated, with subsequent bedrest and transfusion as needed. Perinephric hemorrhage is another cause of postoperative bleeding which should be suspected in cases of clear urine with dropping blood counts and flank pain, although this situation can similarly be managed conservatively with bedrest and transfusion. Delayed bleeding is often secondary to arteriovenous fistula or pseudoaneurysm and occurs approximately 1–3 weeks postoperatively. In cases of unresponsive hemorrhage, angiography with embolization is typically effective, although open surgical exploration with vascular repair and nephrectomy are options in cases where conservative management fails.

Collecting system injury

Perforation

Perforation of the collecting system is a complication that can occur during any portion of the procedure and has been reported in up to 7% of PNL procedures [39]. This complication should be suspected if retroperitoneal structures, perirenal fat or sinus fat is seen, with or without abdominal/flank distention. Fluid extravasation associated with a collecting system perforation can produce ventilation difficulties, electrolyte/hemodynamic abnormalities, and postoperative ileus [40].

This complication can be avoided by paying close attention to access and dilation methods discussed previously and by keeping the working sheath within the collecting system. Additionally, fluoroscopic or endoscopically visualized dilation, sheath placement, and tube manipulation will decrease risk of perforation. Conversely, smaller access tracts, such as those seen with “mini-PNL” or “micro-PNL”, may also introduce an elevated intrarenal pressure and increase the risk of perforation [41].

Once perforation of the collecting system is noted, the procedure should be terminated expeditiously, although the procedure can be completed with low-flow irrigation if the surgery is nearly complete and the patient is stable. A nephrostomy tube should be left in place at the conclusion of the procedure; most perforations heal within 72 h, but it is recommended to perform a nephrostogram approximately 7 days postoperatively to ensure complete healing. Open surgical repair or nephrectomy is rarely necessary [39].

Ureteral avulsion is an extreme form of collecting system perforation that is rare during PNL. It more commonly occurs during incision and dilation of a ureteropelvic junction or during antegrade treatment of ureteral calculi. If a drainage catheter (stent or nephroureteral catheter) can be passed across the defect, healing is common, although occasionally a percutaneous drain or open repair are required.

Stricture/stenosis

Stricture development is a rare complication of PNL, with an incidence of less than 1%, most commonly affecting the proximal ureter and ureteropelvic junction [3, 4]. Strictures are most typically due to inflammation from stone impaction or intraoperative trauma, including lithotripsy-associated injury or urine/stone extravasation. Importantly, postoperative ureteral strictures may be asymptomatic, thus it is recommended that all patients undergoing PNL have routine postoperative imaging to evaluate for silent obstruction [42, 43]. Most ureteral strictures seen after PNL can be managed endoscopically, although length of stricture (> 1 cm), degree of hydronephrosis, and poor renal function are all risk factors for failure of conservative management in these cases.

Infundibular stenosis is a similarly rare complication, with approximately 1–2% risk after PNL [3, 44, 45]. Studies suggest prolonged operative times, large stone burden, and extended nephrostomy drainage as risk factors for this occurrence, possibly due to increased inflammation or prolonged instrumentation [46]. This complication can often be treated endoscopically, although asymptomatic patients with normal renal function can be observed.

Extrarenal stone migration

Extrarenal or extraureteral stone migration is a relatively benign complication as these fragments are generally of little consequence. As long as the stone is not infected and fragment-associated inflammation does not obstruct the urinary tract, treatment is usually not necessary [47, 48]. Intraperitoneal migration of fragments has been reported with open extraction performed to prevent peritoneal complications [49]. In case of migration of fragments out of the urinary tract, endoscopic retrieval should not be attempted, as this may only enlarge the perforation. Yet, it is important to document that the stone is entirely outside the collecting system. This complication can be avoided by applying proper lithotripsy techniques and noticing any form of collecting system perforation early, with prompt cessation of the procedure if necessary.

Retained foreign bodies

Rarely, a piece of equipment used during PNL can break off and remain within the collecting system. This problem can occur at any point of a procedure and as such vigilance is required to prevent such a complication. A wide variety of retained foreign bodies has been reported, from plastic drape fragments and ureteral catheter pieces to wire baskets, laser fibers and portions of Malecot catheters [50,51,52]. Careful manipulation of equipment and close evaluation for device fatigue can decrease the risk of this complication. If a piece of equipment is noted to have broken off into the collecting system, such a foreign body can usually extracted endoscopically with fluoroscopic assistance, although retrograde ureteroscopic access can also be used if it is noted postoperatively.

Injury to surrounding structures

Lung and pleura

The most common peri-renal organs injured during PNL are the lungs and pleura, with this complication reported in 0.3–15.3% of cases [3, 4, 53,54,55,56,57]. It is no surprise that the risk of pleural injury increases with supra-costal access; CT imaging studies have shown that during maximal expiration, a supra-11 approach will theoretically traverse the pleura approximately 80% of the time [58]. This risk decreases to 15–30% with supra-12 approaches, although these rates are higher than those seen clinically [58].

Clinical studies note rates of intrathoracic complications closer to 10–15% with supracostal access (35% with supra-12, 10% with supra-11), compared to 1.5–4.5% with subcostal access [55, 56]. Of note, some studies suggest that operative position may vary the risk of pleural injury, with prone-flexed or supine positions potentially displacing the kidney caudally to allow for upper pole access without supra-costal puncture [59, 60].

Preoperative CT scan is essential for operative planning to determine positioning of access tracts and decrease intrathoracic complications [61]. PNL should be performed through a working access sheath, as the sheath may provide a barrier to the influx of air or fluid into the pleural cavity in cases of thoracic violation. Additionally, routine chest imaging at the conclusion of the procedure (or in the recovery room) can be useful to evaluate for obvious pneumothorax or hydrothorax in cases of supra-costal access [62].

In the case of recognized small-volume, asymptomatic pneumothorax or hydrothorax, the patient may be observed; if the patient becomes unstable or shows signs of pulmonary compromise, tube thoracostomy may be required [63]. While small-bore tubes are useful in this situation, if there is concern for spillage of infected fluid or stone material into the pleural cavity, a full-size chest tube may be more prudent. If these conservative treatments fail or complex effusion/empyema develop, thoracoscopic surgery or thoracotomy may be required, although this need is relatively rare [64].

A more formalized nephropleural fistula can manifest anytime from the conclusion of the procedure to 2 weeks postoperatively; symptoms can range from continued thoracostomy tube drainage to a delayed presentation with shortness of breath. Diagnosis is typically made by retrograde pyelography and treatment is often successful with dual drainage of the pleural space and urinary system (i.e. thoracostomy tube and ureteral stent/nephrostomy tube) [65]. Hemothorax can also occur due to injury of the diaphragm or intra-costal vessels, which course along the underside of each rib. Conservative management with thoracostomy tube and hemodynamic monitoring is reasonable, although thoracoscopic intervention may be required.

Colon

Colonic perforation is a rare complication of PNL as it is uncommon to find this organ in a retro-renal location; fewer than 1% of cases involve colon injury [39, 66,67,68]. Previous estimates show approximately 0.6% of patients harbor a retro-renal colon on preoperative CT scan, although some studies suggest a higher incidence of this finding on prone CT imaging (16.2%), arguing for operative planning with a prone CT [69,70,71]. Risk factors for such an injury have been investigated, with the following patients at higher risk for colonic perforation—congenital renal anomalies such as horseshoe kidney, colonic distention, lower pole puncture, left-sided procedure, previous colonic surgery, older age, and female sex [66, 67, 72]. Of note, supine positioning for PNL does not appear to increase the risk of colonic injury [73].

Early recognition of such an injury is of utmost importance, with a delay in diagnosis leading to severe complications. Signs of colon perforation include passage of gas or feces through or around the nephrostomy tube, intraoperative diarrhea/hematochezia, and peritonitis (often associated with fevers) [66, 67, 72, 74]. Some surgeons recommend nephrostogram at the conclusion of each procedure to rule out colonic injury [66].

Colonic injury can be managed conservatively in the majority of cases, especially if the injury is retroperitoneal and the patient is clinically stable [66, 75]. Double drainage should be established with a ureteral stent and foley along with withdrawal of the nephrostomy tube into the colon, which is often performed under fluoroscopic guidance [67]. The patient should be monitored closely on broad-spectrum antibiotics and low residue diet. Approximately 7–10 days after injury a contrast study should be performed through the colostomy tube to ensure resolution of the nephro-colic fistula, with subsequent tube removal [76]. Open surgical management may be required in patients with transperitoneal injury, peritonitis, clinical instability, sepsis, or in those patients for whom conservative management has failed.

Small intestine

The second and third portions of the duodenum may be injured during PNL, as they are adjacent to the lower pole and renal pelvis of the right kidney. This complication is very uncommon and is most often seen during percutaneous access or with renal pelvis perforation [77]. This issue should be suspected if intestinal mucosa or contents are seen endoscopically, or nephrostogram delineates the small bowel lumen. Surgical exploration is the most common treatment, although small injuries can be managed conservatively. Such management consists of adequate double drainage of the intestine and urinary tract, antibiotics, nasogastric suction, and parenteral nutrition. Nephrostogram and upper gastrointestinal radiologic study should be performed 10–14 days following the perforation to ensure complete closure of the injury.

Liver, gallbladder, and spleen

The liver is rarely injured during PNL, although supra-costal access and hepatomegaly may increase this risk up to 14% [58]. This complication can be avoided by utilizing proper preoperative imaging and access techniques and considering CT-guided access for certain patients. If liver injury is noted, a nephrostomy tube should be left in place for 7–10 days to allow for tamponade and maturation of the tract. Open surgical repair remains an option with failure of conservative management.

The gallbladder is similarly a rare organ for PNL injury, with most patients presenting with peritonitis and signs of septic shock. Typical treatment consists of exploratory laparotomy/laparoscopy with cholecystectomy [73, 78].

Splenic injury is also typically only seen with supra-costal access, with a supra-11 approach increasing the risk as high as 33% [58]. Injury to the spleen can produce significant hemorrhage and hypovolemic shock and, while patients can occasionally be managed non-operatively (with bedrest, tube tamponade, and close monitoring), most patients eventually require splenectomy [73, 79].

Lymphatics

Disruption of lymphatics adjacent to the collecting system during PNL can lead to chyluria, which can often be controlled with optimal urinary drainage and total parenteral nutrition [80]. Additionally, a low fat, medium-chain triglyceride diet with the aid of somatostatin can be useful in some cases. If chyluria continues, retrograde instillation of silver nitrate or povidone-iodine can be performed as sclerotherapy, with open lymphatic ligation as a final option [81,82,83].

Medical complications

Infection and sepsis

Infectious complications are some of the most common and concerning problems that can occur perioperatively when performing PNL. Care must be taken preoperatively to reduce the risk of such perioperative infectious complications. All patients with urinary tract infection must be treated with appropriate antibiotics prior to PNL due to the overwhelming risk of bacteremia and sepsis associated with bacterial extravasation. While a single recommended perioperative antibiotic course has not been completely established, patients with infections should be treated with antibiotics at least 1 week prior to the procedure [84]. The use of prolonged preoperative prophylactic antibiotics in patients with sterile urine is controversial, although many urologists continue to give 1 week of preoperative antibiotics before PNL despite negative culture [85]. To this end, numerous studies have attempted to assess risk factors for infectious complications based on perioperative antibiotic dosing, without consistent results. Studies have noted an improvement in infections with preoperative antibiotic prophylaxis, specifically in patients with large and complex stones or hydronephrosis, although other studies have suggested that only perioperative antibiotics are required if preoperative urine cultures are negative [86,87,88,89,90,91].

Despite proper antibiotic use based on preoperative cultures, patients may still develop bacteremia or sepsis, likely because stone and renal pelvis urine cultures often are not predicted by bladder urine culture [92, 93]. Studies have documented that despite negative preoperative urine cultures, 25–43% of pelvic urine or stone cultures may be positive, with these patients at a significantly greater risk of postoperative urosepsis [93, 94]. In fact, the stone culture organism is more commonly the causative organism of a postoperative uroseptic episode when compared to bladder urine culture and, as such, renal pelvic urine and stone cultures should be sent during PNL to help guide postoperative therapy if needed [95].

Regarding risk profiles, many studies have attempted to isolate the perioperative risk factors for postoperative urosepsis. In addition to positive urine and stone cultures, increased stone burden, history of recurrent urinary infections, renal failure, longer surgical times, and multidrug-resistant bacteriuria are concerning factors that should raise suspicion and possibly alter preoperative antibiotic prophylaxis [96,97,98,99].

Occasionally, purulent urine is encountered at the time of collecting system access. It is reasonable to delay treatment in this setting, leaving a nephrostomy tube in place to drain the collecting system. The expressed fluid should be cultured and the patient should be observed on broad-spectrum antibiotic therapy until the results are known. Some surgeons have had success (and avoided a second procedure) by moving forward with PNL despite purulent access, although these patients were typically carefully selected and this method cannot be recommended in all situations [84, 100]. Of note, despite proper drainage and antibiotic administration, these patients can still develop urosepsis when the stone is eventually treated at a later time [101].

Postoperatively, sepsis has been reported in 0.6–1.5% of patients after PNL, which is typically due to bacteremia and endotoxemia [3, 4, 102]. Patients should be monitored closely for clinical signs or symptoms of infection, including vital sign or laboratory panel changes as well as alterations in mental status. Postoperative leukocytosis and fever are relatively common after PNL, but significant elevations in either of these parameters should be a cause for concern and lead to an escalation of care and antibiotic therapy [103, 104]. Additionally, lactate and procalcitonin levels may be useful for isolating a significant postoperative infection [105]. When a patient is suspected to be experiencing a septic episode, aggressive fluid and antibiotic management is paramount, as well as supportive measures including steroids and/or pressors. Patients who do not respond to these methods may be experiencing alternative pathology, including unrecognized injuries (which can be diagnosed by additional imaging) or fungal infections (especially in immunocompromised or diabetic patients or those with prolonged urinary drainage tubes) [106]. In some cases, patients will present postoperatively with a sepsis-like event with negative cultures due to endotoxemia; these patients require supportive measures alone, but antibiotic therapy should be utilized until cultures are deemed negative.

Loss of renal function

PNL is believed to have minimal long term effect on renal function. Studies that utilized functional imaging have noted small parenchymal scars and focal functional decrease at the access site, although overall renal function remained stable or improved in 84% of patients [107,108,109]. Additionally, studies have shown transient increases of serum creatinine (0.14 mg/dL) and bilateral decreases in individual renal unit creatinine clearance, although all of these injuries resolved after 72 h [110,111,112]. Longer term evaluation noted negligible changes in creatinine 1–2 years after PNL, with functional imaging documenting stable or increased renal function in 94.4% of patients [113,114,115].

Patients with staghorn calculi appear to represent a different group of patients with regard to renal deterioration after PNL; studies estimate a 25% risk of renal functional decline after surgery for a staghorn stone [116]. Risk factors associated with this decline include solitary kidney, recurrent stones, hypertension, complete staghorn calculi, urinary diversion, and neurogenic bladder [117, 118]. Taken together, it seems that the risk of renal functional deterioration in these patients is less apt to be surgically-related and more likely associated with the stone disease and comorbidities.

Acute renal injury resulting in renal loss is a rare complication of PNL, usually secondary to uncontrollable hemorrhage, with an incidence between 0.1 and 0.3% [102, 119]. Prevention of such a complication utilizes previously discussed methods above.

Fluid overload

It is known that irrigation fluid can be absorbed during PNL, with collecting system perforation, bleeding, and other similar complications increasing the risk and amount of fluid absorbed [120]. Careful monitoring of intraoperative fluid input and output can detect this problem, although other signs of fluid absorption may include unexplained hypertension, hypoxemia, and ventilation difficulties. Use of a working sheath and low irrigation pressures can minimize absorption, while normal saline must be used during all PNL procedures to decrease the risk of hyponatremia in cases of fluid absorption. This complication can also be prevented by limiting the procedure duration and terminating the surgery in the setting of significant collecting system perforation; additionally, diuretic administration can be used to facilitate clearance of excess fluid.

Hypothermia

Core body temperature is known to decrease during PNL, with a drop below 36 °C defined as hypothermia. Intraoperative hypothermia can be multifactorial, with causes ranging from anesthetic vasodilation, procedure length, exposed body surface, room temperature, and the use of un-warmed irrigant. Hypothermia may lead to impaired platelet function, altered drug clearances, and increased oxygen consumption due to shivering which can prompt cardiac ischemia or arrhythmias. The risk of hypothermia can be decreased by use of warmed irrigant, patient coverage with heat-preserving drapes, and keeping patients as dry as possible during surgery [121, 122].

Positioning-related injury

Given that PNL is traditionally performed in a prone position, proper positioning is essential, as injuries can occur to the brachial plexus and other peripheral nerves, shoulders can be dislocated, and cutaneous skin trauma is possible. Compared to a supine position, intraoperative anesthesia parameters, including heart rate and peak airway pressures, were seen to worsen in prone position, although other studies demonstrated no change in airway pressures between positions [123, 124].

With a recent increase in supine positioning for PNL around the world, this previously alternative position is becoming more common. While this position appears to be simpler for the anesthesiologist, multiple studies and meta-analyses have relatively inconsistent results. Complication rates have been similar despite positioning method, along with similar hospital stay, operative times, and stone-free rates [125, 126].

The inconsistent data show that no position is safer or more advantageous for the average patient; care must be taken to avoid positioning-related injuries no matter the method utilized. Great care must be taken to pad all pressure points and avoid joint strain, and with attention to detail and proper padding, most problems can be avoided whatever the surgical position. Despite proper positioning, injuries can still occur; if neurapraxia is a possible postoperative concern, neurologic evaluation is recommended, although most of these injuries resolve with time and physical therapy.

Thromboembolic complications

Deep venous thrombosis (DVT) has been reported in 1–3% of patients undergoing PNL [102, 127]. The risk of DVT can be lessened by use of sequential compression devices and thromboembolic disease-prevention stockings in the operating room, as well as stressing early postoperative ambulation. There is little in the way of official guidelines regarding thromboprophylaxis in the perioperative period, although the EAU guidelines recommend against pharmacologic prophylaxis in all patients undergoing PNL and only utilizing mechanical prophylaxis in high-risk patients; they accept that the level of evidence in this case is weak [128]. If DVT is documented on duplex sonography, anticoagulation is typically required with the goal of preventing propagation and embolism; in the immediate postoperative period bleeding may be a concern and as such an inferior vena cava filter may be needed [129]. In patients with mature nephrostomy tracts or patients who are closely watched with minimal bleeding postoperatively, anticoagulation may be safely tolerated.

Air embolism is a reported complication of PNL, although it is extremely rare [130, 131]. This complication may be associated with airflow reversal through the ultrasonic lithotripter. Theoretically, air pyelography may cause an air embolism, yet recent studies have documented large numbers of air pyelograms performed without a single episode [132]. This complication can be recognized by hypoxemia, bradycardia, a fall in end tidal carbon dioxide, or cardiopulmonary arrest; intraoperative diagnosis is made with echocardiography.

If this complication is suspected, the procedure must be terminated and the patient should be placed in the left lateral decubitus position. Theoretically, a central venous line or puncture can be performed in order to attempt aspiration of the air bubble. Patients may need close postoperative cardiopulmonary monitoring, inotropic support, intensive supportive care, and—in cases with cerebral involvement—hyperbaric oxygen therapy [133].

Mortality

Postoperative mortality is extremely rare after PNL, with a rate of approximately 0.2% [134]. In the Clinical Research Office of the Endourological Society (CROES) study of nearly 6000 patients, urosepsis was the cause of the two mortalities reported [135]. Most deaths associated with this procedure are due to sepsis, myocardial infarction, and pulmonary embolism in high-risk patients, suggesting the need for proper preoperative workup and counseling. Additionally, close cardiopulmonary monitoring should be utilized intraoperatively and postoperatively to ensure early diagnosis of associated complications.

Conclusions

PNL can be associated with a large variety of complications, including bleeding, injury to the urinary system, injury to adjacent organs, infection, and even death. Appropriate patient selection and preoperative workup can minimize these complications, as well as understanding of the potential pitfalls as discussed in this review [136]. Patient counseling should focus on the complexity of the procedure and create proper expectations in the perioperative period.

Proper surgical technique is of paramount importance, with great care and focus required to decrease the risk of most intraoperative complications. Increased case loads have been shown to decrease complication rates associated with PNL and thus an experienced surgeon should be able to safely perform this procedure. Most importantly, prompt recognition of complications is essential, as most complications can be managed conservatively. Typically, safety and success are the most common outcomes of PNL procedures.