Percutaneous Nephrolithotomy

Percutaneous nephrolithotomy (PCNL, PCN, PNL; synonym: percutaneous nephrolitholapaxy) is a minimally invasive treatment of urinary stones using an endoscope (endoscopy; see “The surgical procedure” below). In this procedure, kidney stones are removed endoscopically by percutaneous (“through the skin“) puncture of the affected kidney. The procedure has largely replaced open stone surgery for large kidney stones (>2 cm) since the 1980s.

Indications (areas of application)

  • Large kidney stones (> 2 cm)
  • Medium kidney stones (1-2 cm)
  • Stones in the lower calyx group
  • Spout stones
  • Stones in anatomical norm variants (eg, calyx diverticula stones).
  • Stones in which there is a concomitant anatomical transsport disorder (eg, ureteral outlet stenosis/ureteral outlet stenosis).
  • ESWL/URS-refractory stones

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Contraindications

  • Untreated urinary tract infection
  • Untreated coagulation disorders and patients on anticoagulants (anticoagulants; acetylsalicylic acid (ASA) in the dosage of 100 mg/d is not a contraindication; see “Before surgery” below)
  • Atypical colonic interposition/surgical interposition of a section of the large intestine (colon) (especially in the case of purely fluoroscopy-guided puncture)
  • Functionless kidney
  • Tumors of the kidney
  • Pregnancy
  • Anesthesiological contraindications

Before surgery

  • Perioperative antibiotic prophylaxis.
  • Note: PCNL should not be performed with ongoing use of anticoagulants or antiplatelet agents (anticoagulants) or presence of a coagulopathy. Acetylsalicylic acid (ASA) can be continued after careful indication and risk assessment.

The surgical procedure

The patient lies in the supine or prone position during surgery. Increasingly, supine or modified lithotomy positioning is becoming established. PCNL is typically performed with rigid endoscopes (instrument used for diagnosis and therapy in body cavities and hollow organs) of various diameters. In general, the following terms are understood to mean the following outer diameters:

  • Conventional PCNL: 24-32 Ch. (Charrière; the measurement in Charrière divided by 3 is approximately equal to the outer diameter in millimeters).
  • Mini PCNL: 14-22 Ch.
  • Ultra Mini PCNL: 11-13 Ch.
  • Micro PCNL: 4.8-11 Ch.

Puncture is usually combined in Germany under sonographic view (ultrasound) and control by X-ray. This requires a small incision, which is located in the flank and is about 2 1.5 cm long. After insertion of the endoscope into the kidney, the stone(s) can be crushed. Various methods of intracorporeal lithotripsy (stone fragmentation) are available for this purpose (statements from the S2k guideline[1] are provided below):

  • In PCNL, ultrasound lithotripsy probes or ballistic systems demonstrate higher efficacy than stone lasers.
  • Ho:YAG laser is the most effective lithotripsy system when using miniaturized or flexible endoscopes in PCNL.
  • Electrohydraulic lithotripsy should no longer be used in PCNL because of the increased risk of collateral damage.

In conventional PCNL, ultrasonic or ballistic systems are used in most cases, which are also available in combination. Advantage of ultrasound probes is a simultaneous suction of stone fragments, while the ballistic systems have a higher effectiveness. With miniaturized or flexible endoscopes, the holmium:YAG laser is used today.After completion of the procedure, short-term insertion of a percutaneous nephrostomy (renal fistula; used for external urinary diversion) or ureteral splint (ureteral splint; used for internal urinary diversion) is performed, if necessary, to ensure urine drainage. Percutaneous nephrostomy (PCN) as a postoperative urinary diversion should be inserted for:

  • Residual stones (alternative: insertion of a ureteral stent and flexible URS for stone repair).
  • Planned 2nd look PCNL (second look operation).
  • Significant intraoperative bleeding (largest possible PCN corresponding to the puncture channel).
  • Urine extravasation (urine leakage)/perforation of the renal pelvis.
  • Infectious stones
  • Multi-tract PCNL
  • Single kidney or ureteral stenosis/ stricture (scarring narrowing) (alternative: insertion of a ureteral splint).

The operation is performed under general anesthesia.

After the operation

  • Eating and drinking is possible for a few hours after surgery
  • Discharge usually 2 to 3 days after treatment

Possible complications

  • Hemorrhage; most commonly there is venous hemorrhage from the renal parenchyma (in rare cases, hemostasis by selective occlusion of the bleeding vessel is required: in cases of persistent arterial rebleeding, radiological embolization is performed); blood transfusions are required in 7% of cases
  • Fever (10.8%) → antibiotic therapy.
  • Urinary leakage (urinoma/accumulation of urine in the body outside of the urinary tract: 0.2%).
  • Obstruction due to residual fragments
  • Sepsis (blood poisoning) (0.5%) → antibiotic therapy appropriate for resistance, renal diversion, intensive care treatment if necessary.
  • Organ injury (0.4%)
    • Pulmonary and pleural (lung pleura) injuries.
    • Small or large bowel injuries; more common in punctures without ultrasound location).
    • Liver and spleen injuries (very rare).

Relative data in %.