Percutaneous Nephrolithotomy (PCNL) Percutaneous Nephrolithotomy (PCNL) Indications for Percutaneous Nephrolithotomy:
• Calculi >2–3cm
• Staghorn calculi
• Complex calculi
(I am writting is very simply,there are many indications actually)
Although significantly less morbid than open surgery, percutaneous nephrolithotomy
(PCNL) is still the most invasive approach to urinary lithiasis when compared to ureteroscopy or extracorporeal shockwave lithotripsy (SWL). Consequently, this technique is generally reserved for specific needs. Bulky stones greater than 2 cm are frequently best treated with a percutaneous approach to minimize repeat treatments and trauma to the kidney. Complete stone clearance can also avoid the risk of steinstrasse if the ureter is unable to accommodate a large bolus of stone debris. These concerns are especially true of staghorn calculi or complex stones that occupy multiple calyces. Some stones are simply too dense or organic in nature to respond well to SWL and may be best served with an initial percutaneous approach. Calcium oxalate monohydrate calculi are noted to be the densest stones and often experience incomplete fragmentation.Cystine stones are also resistant to shockwave energy, likely owing to their organic origin and their tight crystalline formation. Additionally, residual cystine fragments can
easily act as “seed calculi” leaving the patient with multiple smaller stones rather than their initial large calculus. In light of these difficulties, many authors advocate a percutaneous approach for cystine stones even less than 2 cm in order to achieve complete stone clearance .
Some stones smaller than 2 cm may be best treated with a percutaneous approach if they reside within difficult anatomic locations. Calyceal divertula have a tight neck that will not allow the easy passage of stone debris. If the diverticulum is inaccessible from a retrograde ureteroscopic approach, then percutaneous access can clear any stone material and allow either destruction of the urothelial lining or creation of a wider infundibular orifice (or both). Owing to obvious anatomic constraints, this technique is best reserved for posterior calyces.
Stones within a lower pole calyx may have a difficult time clearing out of this region into the pelvis and down the ureter following SWL. A well-controlled large randomized trial has demonstrated that percutaneous nephrolithotomy is superior to SWL for lower
pole calculi. The difference was particularly dramatic for stones larger than 1 cm. Contraindications for Percutaneous Nephrolithotomy
• Uncontrolled coagulopathy
• Ectopic kidney
• Active urinary tract infection
• Fusion anomalies
• Severe dysmorphism
• Morbid obesity Special note for Staghorn Calculi
Staghorn calculi (either partial or complete) represent a unique challenge for the endourologist . The sheer bulk of the stone burden and the complex branched anatomy of the collecting system require careful planning regarding access and plurality
of access tracts. Additionally, these calculi are typically associated with an infectious etiology. Antibiotics are never able to completely penetrate the interstices of a complex stone, running the risk of a release of bacteria and endotoxin during stone ablation.
Despite these warnings, however, PCNL remains the standard of care for staghorn calculi,replacing anatrophic nephrolithotomy and other open approaches.
Results from many authors have demonstrated the superiority of PCNL over SWL alone. In 1994, the evidence was compelling enough to prompt the AUA Guidelines Committee to recommend PCNL as first line therapy, often combined with SWL to ablate calculi in difficult to reach calyces.Second-look PCNL may also be added to the end of this regimen to “clean-up” any residual fragments left after the shockwave lithotripsy. This technique has been dubbed “sandwich therapy.” Stone-free rates tend to range from 70 to 100% with this approach, with acceptable complication rates. Randomized trials have been performed comparing a combination of PCNL with SWL vs SWL alone. One particularly noteworthy analysis from Meretyk et al. demonstrated a stone-free rate of 74% with combination therapy vs 22% with SWL alone . Nearly half of all shockwave lithotripsy patients had septic episodes whereas the combination patients had an 8% rate. Finally, 26% of the monotherapy patients required ancillary procedures over 6 mo vs 4% of the combination patients over one additional month.
More recently, some centers have moved away from a sandwich technique, relying on aggressive PCNL at the first sitting. This may require the use of a supracostal access or a multi-tract access at the first procedure . These same approaches may remove so much stone burden that there is no longer a need for the “meat” portion of the sandwich (SWL) or the second-look PCNL. Others have moved away from the removal of all residual fragments, electing to treat small remnants with aggressive medical therapy. This therapy should be directed by the information gained from a complete metabolic evaluation and/or stone analysis.Anatomic abnormalities (UPJ obstruction, caliceal diverticulum) or genetic predisposition (cystinuria) that played a role in the formation of the original calculus should be addressed if possible. Residual fragments should be small and expected to have a reasonable chance of spontaneous passage. The presence of infected fragments is generally frowned on as these can easily act as “seed” calculi and reinfect the patient’s urinary tract. Complications
The list of potential complications from PCNL is long and varied. The percutaneous access must traverse multiple tissue layers and planes, including skin, subcutaneous fat,muscle, fascia, perirenal fat, and parenchyma. In addition, difficulties can arise from the location of the access tract, trauma to the renal parenchyma, injury to the collecting system, hemorrhage, fluid shifts or even the physiologic stress of surgery. Rarely, other structures may be abnormally displaced and are at risk of inadvertent damage. An incomplete list includes: colon, small bowel, spleen, liver, gallbladder, and the great vessels.Transfusion rates generally run in the low single digits, but have been reported as high as 50% in some older series. Hemorrhage can arise from the parenchyma of the kidney,from branches of the renal vasculature or from the torn edges of the urothelium. As mentioned in previous sections, increasing the number of access tracts will increase the need for transfusion. A rare but impressive source of postoperative hemorrhage is from the formation of an arteriovenous fistula along the percutaneous tract. These patients can present with massive hematuria and usually require embolization or even nephrectomy.
Urinary tract infection and sepsis are always a risk during this procedure owing to colonization of the urine and sequestration of bacteria within the calculi. Careful attention to preoperative urine cultures and the liberal use of perioperative antibiotics can minimize the risk of overwhelming infections. Patients with known or suspected struvite calculi should be treated with extra care. Rubenstein et al. have demonstrated that even patients with neurogenic bladders and known urine colonization can be safely treated with this technique. These authors have advocated the placement of the nephrostomy access one day before the scheduled procedure to allow time for observation and the early treatment of signs of systemic infection.
Colonic perforation has been reported from multiple authors and sites . This particular complication is thought to be caused by the presence of a retrorenal colon or caused by the placement of the access tract in too lateral a location. Very thin patients may be at higher risk, as are females and left-sided procedures. Surgeons may not notice the problem until after the case has been completed, because the nephrostomy access sheath will likely tamponade the defect and “bypass” the injury. Patients may develop significant fevers or abdominal pain in the postoperative period. Feculent material may be visible in the urine, the urine leak may cause watery diarrhea or stool may exude from the nephrostomy tract. Most authors recommend the placement of a ureteral catheter or stent to attempt to divert the urine down towards the bladder and away from the nephrocolonic fistula. In addition, the nephrostomy should be pulled back into the colonto allow the fistula to heal spontaneously. Colon resection is always a distinct possibility but is usually avoided. Intrathoracic complications can arise from upper pole or supracostal access tracts when the pleura are violated. Pneumothorax, hydrothorax, or hemothorax have been reported. Intraoperative manifestations may include difficulty with mechanical ventilation, poor oxygenation, hypotension or cardiovascular collapse. The fact that the patient is usually in a prone position for this procedure can make recognition and management of a severe intrathoracic complication quite challenging for the anesthesiologist. Most of these patients can be managed with the placement of a draining chest tube, which may be placed intraoperatively if the complication is recognized during the procedure.Intraoperative fluoroscopy can be used to diagnose the condition with poor penetration of the ipsilateral lung field or for the correct interpretation of a collapsed lobe.
Your friend has Both Hypertension and Diabetes,definitely there is additional risk for having associated nephropathty.He is also at risk for infection. |