Etiology of hemorrhage from percutaneous nephrolithotomy

Bleeding during and after PCNL can occur at any step throughout the procedure, including needle puncture, dilation of the percutaneous tract, excessive torqueing of the renal parenchyma through an established access sheath, aggressive stone manipulation and extraction, from collateral damage to adjacent organs and blood vessels, during nephrostomy tube removal, and in the immediate or delayed postoperative period [8]. Hemorrhage results from either damage to the kidney parenchyma, disruption of the peri‐ or intrarenal vessels, or injury to adjacent structures.

Renal parenchymal bleeding, believed to stem most commonly from the interlobular vessels, is often mild, apparent during surgery, and frequently can be controlled with intraoperative tamponade from the access sheath, and with larger bore nephrostomy or nephroureteral catheters postoperatively. Injury to the larger renal vessels, such as the arcuate, interlobar, lobar, and segmental vessels, is thought to cause more significant bleeding that may limit vision during PCNL and can cause continued significant blood loss postoperatively as well. For vessels in spasm, bleeding may be minor during surgery, but once the spasm abates, bleeding and its effects often become apparent within the first 24–48 hours postoperatively.

Injury to these larger vessels is also believed to be the cause of delayed bleeding. Such delayed bleeding often takes one of two forms: arteriovenous fistulas and pseudoaneurysms. Arteriovenous fistulas arise when a lacerated artery and vein in proximity to each other form a direct connection while healing. Pseudoaneurysms result when surgery injures the wall of a high‐pressure artery and blood then leaks into a lower pressure area such as the collecting system, connective tissue, or vein [9]. In both of these cases, significant renal bleeding can present in the early postoperative course or in delayed fashion as late as a number of weeks postoperatively.

Risk factors associated with hemorrhage during percutaneous nephrolithotomy

Myriad factors have been linked to PCNL‐related hemorrhage, and can be grouped together as patient‐related factors, operative‐related factors, and stone‐related factors.

Operative‐related factors

Operative and technical factors that have been shown to influence and increase bleeding risk include longer operative duration, larger access tract size, less surgeon experience, use of multiple access tracts, upper pole calyceal access, longer intraoperative time to successful renal puncture and larger bore nephroscopes [10, 17–23]. Compared with smaller access sheaths (≤18 Fr), larger access sheath size was associated with increased hemorrhage risk (threefold increased risk for access sheaths 24–26 Fr and almost fivefold increased risk for access sheaths 27–30 Fr) [24]. Increasing number of access tracts, in particular three or more, routinely appears to correlate with increased risk for higher blood loss and transfusions following PCNL [17, 20–22, 25].

Increasing operative time has also been shown to increase bleeding risk. Though most likely a continuum, surgical duration in excess of approximately 110–120 minutes has been predictive of post‐PCNL bleeding [26, 27]. At least one study has suggested that less surgeon experience was associated with an almost threefold elevated hemorrhage risk (0.6% for an experienced endourologist compared to 1.7% for a general urologist or trainee) [18].

A few studies have evaluated the relationship between PCNL‐related hemorrhage and hospital case volume, and the evidence remains equivocal as to how hospital PCNL volume influences bleeding risk. One study from the United States used the Nationwide Inpatient Sample and found transfusion rates were highest in the lowest and highest quartile volume centers on univariate analysis, however hospital PCNL case volume was not found to independently predict for transfusions on multivariate analysis [28]. In another study from the United Kingdom, no difference in major hemorrhage events was seen among those hospitals performing low (<10 PCNLs per year; 1.3%), medium (10–20 PCNLs per year; 1.5%), and high (>20 PCNLs per year; 1.5%) volumes of PCNLs [29]. Results from the Global PCNL Global study did show a higher reported rate of bleeding (9% vs. 5.5%), mean hemoglobin change (3.9 vs. 3.5 mg/dl), and blood transfusion rate (5.2% vs. 3.4%) in low volume (<77 PCNLs per year) compared to high‐volume (>77 PCNLs per year) centers [30].

Several studies have shown that renal access obtained by a urologist is associated with less bleeding, fewer complications, and a higher stone‐free rate than renal access obtained by a radiologist [31–33]. This is thought to be related to the fact that the goals of the radiologist and urologist may differ in these circumstances. The typical tract created by the urologist is often a more direct route, and often more superiorly located (Figure 33.1). It is prudent to assess the radiologist‐obtained renal access tract prior to tract dilation, and this can be done with multiplanar fluoroscopy and antegrade nephrostography. If suboptimal access is found, there should be a low threshold for obtaining a new, better access.

Preoperative patient assessment and optimization

Absolute contraindications to PCNL include uncorrected coagulopathy and active infection. A complete history and physical examination is important in all patients prior to PCNL, and close attention should be paid to personal and family history of blood dyscrasias and coagulopathic states (clotting factor deficiencies, idiopathic thrombocytopenic purpura, coronary artery stenting, mechanical heart valves, atrial fibrillation, venous thromboembolism, etc.). Medications should be reviewed with the patient with a particular eye towards antithrombotic medications and herbal supplements. Full laboratory evaluation, including complete blood count, serum electrolytes, creatinine level, and coagulation parameters, are important to determine preoperatively. Appropriately screened and cross‐matched blood products should be available.

Previous renal and retroperitoneal surgery should be specifically elicited, as previous open renal stone surgery may increase the risk of angioembolization, while prior PCNL may not [34]. Preoperative cross‐sectional imaging is recommended to help fully understand renal stone burden and anatomy, and to evaluate for anatomical abnormalities and perinephric organ location. Preoperative negative urine cultures should be the goal, and review of prior positive urine cultures and sensitivities are important in patients with a history of urinary tract infections, as these can influence perioperative antibiotic choices.

Scrutiny of any antiplatelet and anticoagulant medications is paramount as the widespread use of these agents becomes more frequent and the number of agents utilized continues to grow. Determining the indications for such antithrombotics is imperative and can have ramifications on the perioperative management of such medications, including the relative risks of continuing versus stopping them, and whether bridging regimens are indicated. Further details on this topic can be found in Chapter 5.

In the operating room, immediately preceding PCNL, maintaining adequate patient temperature is imperative as efficient clot formation depends on body temperature, and lower core body temperatures are associated with inefficient clot formation [35, 36]. To this end, temperature monitoring in the perioperative period is important, and increasing ambient room temperature and utilizing convective air‐warming systems can combat rapid body temperature losses associated with clothes removal and anesthetic induction prior to the start of surgery. During patient positioning alone, core body temperatures can fall by approximately 1°C [36, 37]. Furthermore, it is important to use warmed irrigation fluid when available.