Percutaneous Nephrostomy

Percutaneous nephrostomy, or nephropyelostomy, is an interventional procedure that is used mainly in the decompression of the renal collecting system. Since the publication of the first report describing this procedure in 1955,[1] percutaneous nephrostomy catheter placement has been the primary option for temporary and at times long term drainage of an obstructed collecting system.[2, 3, 4]

With proper training, technical success is achieved in more than 95% of cases.[5] Diagnostic imaging often demonstrates the level and cause of obstruction; however, at the time of the catheter 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. In some cases, the obstruction has 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. 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 postoperative edema, percutaneous nephrostomy allows the edema to subside. Percutaneous nephrostomy may similarly facilitate the management of urinary fistulas.

Indications for percutaneous nephrostomy include the following:

• Urinary diversion:

  • Urinary obstruction secondary to calculi

  • Urinary fistula and/or leaks, eg, traumatic or iatrogenic injury, malignancy, inflammation, hemorrhagic cystitis

  • Nondilated obstructive uropathy

  • Urinary tract obstruction related to pregnancy

  • Urinary obstruction related to renal transplant complications

  • As a part of decompression of perinephric fluid collections, eg, abscess, urinoma

• Access to the collecting system:

  • For interventions, eg, direct infusion of substances for dissolving stones, chemotherapy, and antibiotic and antifungal therapy

  • For endourological procedures, eg, stricture dilatation, antegrade ureteral stent placement, stone retrieval, pyeloureteroscopy, or endopyelotomy

Contraindications for percutaneous nephrostomy include the following:

• Bleeding diathesis (most commonly, uncontrollable coagulopathy)

• Uncooperative patient

• Uncontrolled hypertension[6]

• Severe hyperkalemia (>7 mEq/L); this should be corrected with hemodialysis before the procedure[7, 8, 9]

Preprocedural evaluation

The following steps are included the preprocedural evaluation for percutaneous nephrostomy (note that the list is not all-inclusive and may differ from the preprocedural preparation performed):

• Informed consent is obtained from the patient, next of kin, or healthcare proxy

• Appropriate laboratory studies are reviewed or ordered if not available, including prothrombin time, activated partial thromboplastin time, platelet count, blood urea nitrogen and creatinine levels, hematocrit and hemoglobin levels, white blood cell count, and urinalysis and urine culture

• Pertinent images (eg, sonograms, computed tomography (CT) scans, intravenous (IV) urograms, or radionuclide scintigrams) are reviewed to assess the location of the colon, liver, and spleen and help determine the optimal approach. Scintigrams may assist with decision making process for the procedure

• IV 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 patient receives nothing by mouth for 4-8 hours before the procedure

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 hour 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 culture results are not available, use of a broad-spectrum antibiotic is recommended.

Some have advocated placing percutaneous nephrostomy tubes without performing preprocedural coagulation studies; however, 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 and modality for guidance is chosen. In most cases, guidance involves ultrasonography,[10] though either conventional fluoroscopy or CT (e.g. CT fluoroscopy) may also be used.[11]

Once the guidance method is determined, the access system is selected. Currently available systems include the micropuncture set (Cook, Bloomington, IN), the AccuStick introduction system (Boston Scientific, Natick, MA), and the Hawkins needle. The first 2 systems are 21- and 22-gauge needle systems, whereas the third is an 18-gauge system. Because of the smaller needles, the first 2 systems are often more difficult to visualize on ultrasonography than the Hawkins needle; however, they are associated with a significantly lower bleeding risk.

Currently, most interventionalists use the following 2 main types of nephrostomy tubes, both of which have an end that is secured in the renal pelvis by locking the distal portion of the tube (see the image below):

• 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 retracts slightly so that the tulip portion is larger than the tube diameter; these catheters are mainly used when the renal pelvis is small (because the patient is small) or when a large staghorn calculus is present

  Percutaneous nephrostomy. Shown are two types of nephrostomy tubes: the Malecot (top) tube, and the pigtail catheter (bottom).

In a study comparing catheters with and without locking strings, Chuang et al found no significant difference in complication rate between the 2 types after 90 days.[12]

The patient is commonly placed in a prone or prone-oblique position with the target side elevated. The expected region of the percutaneous nephrostomy should be evaluated by means of ultrasonography, CT, or fluoroscopy, and the puncture site marked. This region should then be prepared (eg, cleansed with povidone-iodine solution) and draped in the usual manner.

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

Postprocedural management and follow-up may include the following:

• Bed rest for 4 hours

• Resumption of 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

After appropriate patient preparation (see Periprocedural Care), a small skin nick is made at the puncture site to facilitate passage of the needle into the skin.

Puncture site selection is crucial for minimizing the risk of hemorrhage.[13] The best route for needle entry into the renal collecting system is via an oblique posterolateral approach along the Brödel line into the end of a posterior calyx. 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-pole or middle-pole calyx under ultrasonographic guidance. If the collecting system is not dilated, intravenous (IV) administration of contrast medium may be required to achieve adequate visualization of the target. Once the needle is inserted into the calyx and into the collecting system (see the image below), the stylet is removed, and urine is returned if an obstruction is present.

If no urine is present, there are a few maneuvers that may be tried. 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 probably within the collecting system.

Otherwise, a 0.018-in platinum-tipped wire (see the image below) may be used to probe the region, or a small amount of contrast agent may be injected to check the positioning. Injection of 10 mL of medical-grade carbon dioxide or room air may be done 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 the contrast agent.

After the collecting system has been 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 withdrawal of too much urine for culture should be avoided because these can cause bacterial seeding or render access difficult if the wire is inadvertently lost. As a rule, the amount of contrast agent used for injection is equal to the amount of urine removed.

Once access into the collecting system has been obtained, over the wire introducer exchanges are continued until a 0.035-in. wire can be placed into the renal pelvis or down the ureter. The tract should then be dilated with polytetrafluoroethylene dilators (some authors have used metal dilators[14, 15] or cutting balloons[16] ). The drainage catheter should be flushed, and the metal stiffener that comes with the kit should be inserted.

The catheter should be advanced into the proximal renal parenchyma over the 0.035-in. guide wire, the metal stiffener should be loosened, and the catheter advanced off the trocar and 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 (see the image below).

The position of the catheter 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 polypropylene) and attached to an external drainage bag.[17]

In a retrospective study of 333 patients who underwent a percutaneous nephrolithotomy using a retrograde technique, stone clearance and complication rates were comparable to percutaneous nephrolithotomy with antegrade access.[18]

A study by Cui et al indicated that intracavitary contrast-enhanced ultrasonography (ICCEUS) can be effectively used to guide percutaneous nephrostomy. All 45 of the study’s percutaneous nephrostomies were successfully carried out (on 35 patients total) using this imaging modality, with correct insertion of the needle and catheter confirmed through ICCEUS and the obstruction located in all cases. In addition, using ultrasonographic contrast agent, catheter dislodgement was diagnosed in five patients.[19]

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 and their frequencies are as follows:

• Massive hemorrhage requiring transfusion, surgery, or embolization (1-3%)[20]

• Pneumothorax (< 1%)

• Microscopic hematuria (common)

• Pain (common)

• Extravasation of urine (< 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%)

Misra and colleagues undertook a detailed retrospective case review to assess survival and complication rates of 36 patients who underwent percutaneous nephrostomy for ureteric obstruction due to pelvic malignancy. Median survival was 78 days (range 4-1,137), with dislodgement of the nephrostomy tube the most common serious complication which led to the greatest morbidity, sometimes requiring repeat nephrostomy insertion. With a median of hospital stay of 23 (range 3-89) days, 29 % of their remaining lifetime was spent in hospital. Because percutaneous nephrostomy in patients with advanced pelvic malignancy does not always prolong life, and is associated with serious complications, the researchers recommend the decision to undergo the procedure must be include a full informed discussion with the patient and their family.[21]

The goals of pharmacotherapy are to reduce morbidity and prevent complications.

Class Summary

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 based on urine culture results, if available. If culture results are not available, use of a broad-spectrum antibiotic is recommended.

Ceftriaxone (Rocephin)

Ceftriaxone is a third-generation cephalosporin with broad-spectrum, gram-negative activity; it has lower efficacy against gram-positive organisms and higher efficacy against resistant organisms. Ceftriaxone arrests bacterial growth by binding to 1 or more penicillin-binding proteins. Patients at low-risk of infection are given a single intravenous dose of 1 g of ceftriaxone 30 minutes to 1 hour prior to intervention.

Cefazolin

Cefazolin is a first-generation semisynthetic cephalosporin that arrests bacterial cell wall synthesis, inhibiting bacterial growth. Patients at low-risk of infection are given a single intravenous dose of 1 g of cefazolin 30 minutes to 1 hour prior to intervention.

Cefuroxime (Ceftin, Zinacef)

Cefuroxime is a second-generation cephalosporin that maintains the gram-positive activity of first-generation cephalosporins; it adds activity against Proteus mirabilis, Haemophilus influenzae, Escherichia coli, Klebsiella pneumoniae, and Moraxella catarrhalis. Patients at low-risk of infection are given a single intravenous dose of 1.5 g of cefazolin 30 minutes to 1 hour prior to intervention.

Class Summary

Pain control is essential to quality patient care. Analgesics ensure patient comfort, promote pulmonary toilet, and have sedating properties that are beneficial for patients who experience pain.

Fentanyl citrate (Duragesic, Abstral, Actiq, Fentora, Onsolis)

Fentanyl citrate is a synthetic opioid that has 75-200 times more potency and a much shorter half-life than morphine sulfate. It has fewer hypotensive effects than morphine and is safer in patients with hyperactive airway disease because of minimal or no associated histamine release. By itself, fentanyl citrate causes little cardiovascular compromise, although the addition of benzodiazepines or other sedatives may result in decreased cardiac output and blood pressure.

Fentanyl citrate is highly lipophilic and protein-bound. Prolonged exposure to it leads to accumulation of the drug in fat and delays the weaning process. Consider continuous infusion because of the medication's short half-life.

The parenteral form is the drug of choice for conscious-sedation analgesia. Fentanyl citrate is ideal for analgesic action of short duration during anesthesia and the immediate postoperative period. It is an excellent choice for pain management and sedation with short duration (30-60 min) and is easy to titrate. The drug's effects are easily and quickly reversed by naloxone. A dosage of 50-100 mcg/dose may be administered 30-60 minutes prior to the procedure.

Class Summary

By binding to specific receptor sites, these agents appear to potentiate the effects of GABA and facilitate inhibitory GABA neurotransmission and the action of other inhibitory transmitters.

Midazolam

Midazolam is a shorter-acting benzodiazepine sedative-hypnotic useful in patients requiring acute and/or short-term sedation. Midazolam is also useful for its amnestic effects.

Class Summary

Local anesthetics are used for local pain relief.

Lidocaine (Xylocaine with Epinephrine)

Lidocaine 1-2% with or without epinephrine (1:100,000 or 1:200,000 concentration) is used. Lidocaine is an amide local anesthetic used in 1-2% concentration. The 1% preparation contains 10 mg of lidocaine for each 1 mL of solution; the 2% preparation contains 20 mg of lidocaine for each 1 mL of solution. Lidocaine inhibits depolarization of type C sensory neurons by blocking sodium channels. Epinephrine prolongs the duration of the anesthetic effects from lidocaine by causing vasoconstriction of the blood vessels surrounding the nerve axons.