Percutaneous Nephrostomy 

Percutaneous nephrostomy, or nephropyelostomy, is an interventional procedure used mainly in the decompression of the renal collecting system. Since Goodwin et al published a report of the first series involving this procedure in 1955,^[1] percutaneous nephrostomy catheter placement has been the prime procedure for the temporary drainage of an obstructed collecting system.^{[2, 3, 4]}

With proper training, technical success is achieved in more than 95% of cases. Images often demonstrate the level and cause of obstruction; however, at the time of tube placement, the cause of obstruction may not be known. Often, the ureteral obstruction is acute and is caused by ureteral calculi or traumatic ureteral injury. The obstruction may have a chronic cause, such as urothelial malignancy or extrinsic compression associated with bleeding or neoplasm.

Frequently, the obstructed system becomes infected, and antibiotics are unable to penetrate the kidney when the purulent material cannot be drained. In these cases, percutaneous nephrostomy is an attractive treatment alternative because it allows decompression of the obstructed system, permits specimen collection, and creates a route for antibiotic instillation if needed. This procedure decreases the risk of urosepsis associated with acute surgical intervention. Often, patients may avoid surgery because the obstructing calculus spontaneously passes after the edema within the ureter subsides. If the obstruction is the result of postsurgical edema, percutaneous nephrostomy enables the edema to subside. The same is true with urinary fistulas.

• Temporary urinary diversion associated with urinary obstruction secondary to calculi
• Diversion of urine from the renal collecting system in an attempt to heal fistulas or leaks resulting from traumatic or iatrogenic injury, malignant or inflammatory fistulas, or hemorrhagic cystitis
• Treatment of nondilated obstructive uropathy
• Treatment of urinary tract obstruction related to pregnancy
• Treatment of complications related to renal transplants
• Access for interventions such as direct infusion of substances for dissolving stones; chemotherapy; and antibiotic or antifungal therapy
• Access for other procedures (eg, benign stricture dilatation, antegrade ureteral stent placement, stone retrieval, pyeloureteroscopy, endopyelotomy)
• Decompression of nephric or perinephric fluid collections (eg, abscesses, urinomas)

• Bleeding diathesis (most commonly, uncontrollable coagulopathy)
• Uncooperative patient
• Severe hyperkalemia (>7 mEq/L) should be corrected with hemodialysis before the procedure.^{[5, 6, 7]}

• After proper positioning, the patient is given an appropriate medication for conscious sedation (eg, fentanyl and Versed) and a local anesthetic, usually 1% lidocaine to anesthetize the skin.

• Currently, most interventionalists use 2 main types of nephrostomy tubes. Both of these types have an end that is secured in the renal pelvis by locking the distal portion of the tube (see image below). The types are the following: Percutaneous nephrostomy. Shown are two types of nephrostomy tubes: the Malecot (top) tube, and the pigtail catheter (bottom).

  • Pigtail (locking-loop or Cope-loop) catheter: The locking loop of the catheter is formed within the renal pelvis by tugging gently on the internal suture and locking the catheter in place.
  • Malecot (tulip-shaped) catheter: The catheter tip slightly retracts so that the tulip portion is larger than the tube diameter. These catheters are mainly used when the renal pelvis is small because of the patient's size or when a large staghorn calculus is present.
• According to a comparative study of catheters with and without locking strings, Chuang et al found no significant difference in the complication rate after 90 days.^[8]

• The patient is commonly placed in a prone or prone-oblique position; the side to be punctured is elevated.
• The region should be evaluated with sonography, CT, or fluoroscopy, and the site should be marked.
• This region should then be prepared (eg, cleansed with Betadine solution) and draped in the usual manner.

Preprocedural evaluation

• The following steps are included the preprocedural evaluation performed before percutaneous nephrostomy tube placement at the Medical College of Virginia. (This list is not all-inclusive, and the preprocedural preparation at other centers may differ.)

  • Informed consent is obtained from the patient, next of kin, or healthcare proxy.
  • Laboratory studies, including determination of prothrombin time (PT), activated partial thromboplastin time (aPTT), platelet count, BUN and creatinine levels, hematocrit (Hct) and hemoglobin (Hgb) levels, WBC count, and urinalysis and urine culture, are made.
  • Pertinent images (eg, sonograms, CT scans, intravenous urograms [IVUs], radionuclide scintigrams) are reviewed to assess the location of the colon, liver, and spleen in determining the approach.
  • Intravenous access is established and the patient is adequately hydrated.
  • Prophylactic antibiotics are administered 60 minutes before the procedure, especially if pyonephrosis is suspected or if the obstruction is caused by a renal calculus. The use of antibiotics is somewhat controversial; however, in patients with a known urinary tract obstruction, antibiotics should be administered before the procedure (preferably 1 h before puncture) and should be continued for at least 24 hours after the procedure. Antibiotics should be chosen on the basis of urine culture results, if available. If the results are not available, use of a broad-spectrum antibiotic is recommended.
  • The patient should receive nothing by mouth (NPO) for 4-8 hours before the procedure, for conscious sedation precautions.
  • Some have advocated the placement of percutaneous nephrostomy tubes without performing preprocedural coagulation studies, although the authors disagree with this approach unless the situation is an absolute emergency. Because the kidney is highly vascular, needle puncture and tract dilation in a patient with a coagulopathy could result in massive hemorrhage.

Guidance and selection of access system

• After the preprocedural evaluation, an appropriate approach or means of guidance is chosen. In most cases, guidance involves sonography, although conventional fluoroscopy or CT (ie, CT fluoroscopy) may be used.
• Once guidance is determined, the access system is selected. Many are available today. Common access systems include a micropuncture set (Cook, Bloomington, Ind), the Accustick introduction system (Medi-Tech/Boston Scientific, Watertown, Mass), and a Hawkin needle. The first 2 systems are 21- and 22-gauge needle systems, whereas the Hawkin needle is 18-gauge. The first 2 systems are more difficult to visualize under sonographic guidance than the Hawkin needle is; however, the risk of bleeding is significantly less with the smaller-gauge needles.

Procedure

• The patient is commonly placed in a prone or prone-oblique position; the side to be punctured is elevated. The region should be evaluated with sonography, CT, or fluoroscopy, and the site should be marked. This region should then be prepared (eg, cleansed with Betadine solution) and draped in the usual manner. The patient is given an appropriate medication for conscious sedation (eg, fentanyl and Versed) and a local anesthetic, usually 1% lidocaine to anesthetize the skin. A small skin nick is made to facilitate passage of the needle into the skin.
• Puncture site selection is crucial in minimizing the risk of hemorrhage. The best route for needle entry into the renal collecting system is through an oblique posterolateral approach along the Brödel line into the end of a posterior calix. This line is near the posterior axillary line and is about 2-3 cm below the 12th rib. A percutaneous nephrostomy tract that approaches along the Brödel line is associated with the smallest risk of substantial arterial injury and subsequent hemorrhage.
• The needle (22 or 21 gauge) is angled toward a posterior lower or middle pole calix under ultrasound guidance. If the collecting system is not dilated, the intravenous administration of contrast medium may be required to visualize the target. Once the needle is inserted into the calyx and into the collecting system, the stylet is removed, and urine is returned if an obstruction is present.
• If no urine is present, a few maneuvers may be used. A 10-mL syringe should be attached to the needle hub, and the needle and syringe should be retracted slightly. If urine is aspirated, the tip is likely within the collecting system. Otherwise, a 0.018-in platinum-tipped wire may be used to probe the region, or a small amount of contrast agent may be injected to check the position. Ten cubic centimeters of medical-grade carbon dioxide or room air may be injected to confirm that the needle is positioned in the posterior calyx. With the patient in the prone position, the posterior calyces will be filled with the gas, whereas the anterior calyces will be filled with contrast medium.
• After the collecting system is accessed, a urine sample may be obtained and sent for routine culture and sensitivity testing. Contrast material should be gently injected into the collecting system to confirm the location. Overdistention of the system with contrast material or the withdrawal of too much urine for culturing should be avoided, because these can cause bacterial seeding or lead to difficulty in gaining access if the wire is inadvertently lost. In common practice, the amount of contrast agent used for injection is the same as the amount of urine removed.
• Once access into the collecting system is obtained, successful wire exchanges should occur until a 0.035-in J-tip wire is placed into the renal pelvis or down the ureter. Then, the tract should be dilated with Teflon dilators. The drainage catheter should be flushed, and the trocar that comes with the kit should be inserted. The catheter should be advanced into the proximal renal parenchyma over a 0.035-in guidewire, the trocar should be loosened, and the catheter should be slipped off the trocar into the renal pelvis. The internal wire should be pulled to lock the pigtail catheter, and the catheter should be seated appropriately within the renal pelvis. The catheter position should be confirmed with the use of contrast material, and the catheter should be tied to the skin with suture (2-0 silk or 2-0 Prolene sutures) and attached to an external drainage bag (see images below).^[9] Percutaneous nephrostomy. The needle is positioned in the mid-pole posterior calyx, filled with air. A filter in the inferior vena cava. A 0.018-inch guidewire has been advanced through the needle into the ureter. An 8F locking pigtail catheter has been placed in the renal pelvis.

Postprocedural management and follow-up

• Postprocedural management and follow-up may include the following:

  • Bedrest for 4 hours
  • Return to the preprocedural diet
  • Checking of vital signs every 30 minutes for 4 hours and then every shift
  • Antibiotic therapy, if infection is identified or suspected
  • Catheter flushing with 5 mL of bacteriostatic isotonic sodium chloride solution and then aspiration every 6-12 hours
  • Monitoring of urine output

• Major complications with percutaneous nephrostomy tube placement include the following:

  • Bleeding
  • Sepsis
  • Injury to an adjacent organ
• Other major complications, though somewhat rare, have been reported to occur in as many as 5% of patients. Complications of percutaneous nephrostomy may include the following:

  • Massive hemorrhage requiring transfusion, surgery, or embolization (1-3%)^[10]
  • Pneumothorax (< 1%)
  • Microscopic hematuria (common)
  • Pain (common)
  • Urine extravasation (< 2%)
  • Inability to remove the nephrostomy tube because of crystallization around the tube site
  • Death (0.2%)
  • Sepsis (1.3%)
  • Catheter dislodgement during the first month (< 1%)