Percutaneous Nephrostomy and Antegrade Ureteral Stenting
Anne M. Covey
Krishna Kandarpa
Introduction
There are four types of percutaneous urinary drainage catheters:
1. Percutaneous nephrostomy (PCN) refers to an external drainage catheter, placed via a flank approach, positioned in the renal pelvis (Fig. 53.1A).
2. A nephroureteral stent/nephroureterostomy enters the collecting system via a flank approach (like a PCN) with a locking loop in the renal pelvis, and extends down the ureter terminating in the bladder, allowing both internal and external drainage (Fig. 53.1B). These catheters are less prone to dislodgment than a PCN, especially in large patients.
 FIGURE 53.1 • Types of renal drainage: (A) Percutaneous nephrostomy is an obligate external drainage catheter; (B) nephroureteral catheter can drain both internally and externally; (C) ureteral stent is an internal device draining into the native bladder; and (D) retrograde nephrostomy, placed via an ileal conduit, drains the renal pelvis to the urostomy device on the anterior abdominal wall. |
3. A ureteral or “double-J” stent is an internal catheter that extends from the renal pelvis to the bladder and can be placed in patients who are able to fill and empty their bladder normally (Fig. 53.1C). Stents relieve patients of the lifestyle limitations associated with an exteriorized device.
4. Retrograde percutaneous nephrostomy catheters are placed through a urinary stoma (i.e., ileal conduit). The locking loop of the catheter is positioned in the renal pelvis and the hub exits the stoma draining directly into the ostomy bag (Fig. 53.1D).
1. Obstructive uropathy including ureteral obstruction from iatrogenic, neoplastic, or inflammatory causes
2. Urinary diversion
a. Urine leak
b. Vesicovaginal or vesicocolic fistula
3. Access for percutaneous intervention
a. Percutaneous nephrolithotomy
b. Tumor biopsy and/or ablation
c. Stricture dilation
4. Preoperative localization of the ureter
5. Before and after extracorporeal shock wave lithotripsy (ESWL)
6. Following a surgical procedure involving the ureter to maintain patency during healing
Contraindications
1. Uncorrectable coagulopathy—the risk of not performing drainage is weighed against the risk of bleeding and kidney loss. Specific to antegrade ureteral stents
1. Untreated bladder outlet obstruction
2. Untreated urinary tract infection
3. Spastic or noncompliant bladder
4. Bladder fistula
5. Nonnative bladder
Preprocedure Preparation
1. Prior to renal drainage, cross-sectional imaging is important to evaluate the presence of hydronephrosis, anatomic variants (duplication, malposition, horseshoe kidney), cysts, tumors, stones, and/or perinephric urinoma. On occasion, radionuclide renography can be useful in measuring differential renal function.
2. Patient education should include a description of the procedure, risks and complications, alternative therapies, catheter maintenance, and long-term plan.
3. Relevant labs include hematocrit (Hct), white blood cell (WBC), platelet count, international normalized ratio (INR), and creatinine (Cr).
4. Coagulopathy should be corrected to local guidelines. Typical goals include an INR of <2.0 and a platelet count >50,000 per µL. Oral anticoagulation should be withheld, utilizing a bridging strategy if anticoagulation cannot be stopped entirely.
5. Obtain urinalysis and urine culture and sensitivity, if relevant to the case.
6. Nil per os (NPO) according to hospital guidelines to allow safe sedation. Patients can have up to 8 oz of clear liquids 2 to 6 hours prior to the procedure and are strict NPO for the 2 hours prior.
a. Anesthesia consultation may be considered for patients who have difficulty with prone positioning or with respiratory compromise that may be exacerbated by prone position.
7. Establish intravenous (IV) access for sedation and preprocedure antibiotic prophylaxis, if needed:
a. Risk stratified appropriate prophylactic antibiotics reduce the rate of infectious complications (5,6).
(2) High-risk patients (including patients with stones) receive ceftriaxone 1 g IV every 24 hours or ampicillin 1 to 2 g IV every 6 hours plus gentamicin at 5 mg per kg IV every 24 hours.
b. Antibiotics are not routinely given after the procedure but may be warranted based on signs of infection.
c. The American Heart Association no longer recommends antibiotics for the purpose of preventing bacterial endocarditis in patients who are to undergo urinary tract procedures (7).
 FIGURE 53.2 • The two basic shapes of self-retaining drainage tubes. A: Malecot or tulip type. B: Cope self-retaining loop. |
8. Catheter selection
a. Options to consider when choosing catheters for urinary drainage include catheter material, locking mechanism, size, and shape. The most common materials include hydrophilic- or nonhydrophilic-coated silicone or polyurethane. Hydrophilic coating facilitates placement by reducing friction but may promote encrustation because it is permeable to inorganic salts. Silicone is softer and generally more comfortable for patients, but it is less strong, requiring a thicker wall to have the same tensile strength as polyurethane (8).
b. A Malecot- or tulip-type locking mechanism is designed so the distal sides of the catheter flare outward (Fig. 53.2A). This occupies less space than a loop catheter and is useful when there is a very small renal pelvis or when a staghorn calculus fills the renal pelvis. The most common locking mechanism is the Cope or “locking loop” that is formed by pulling on a monofilament suture that runs through the body of the catheter (Fig. 53.2B).
c. In most cases, an 8 Fr. catheter is sufficient for drainage. In cases of pyonephrosis or hematuria with clots, 10-Fr. or 12-Fr. catheters may decrease the incidence of catheter occlusion.
Procedure
Percutaneous Nephrostomy
1. Patient position: Prone or prone-oblique when possible. During pregnancy, the patient may only be comfortable lying on her side.
2. Fluoroscopy and/or ultrasound are used to determine an appropriate access site which is then prepped and draped.
3. The skin entry site is along the ipsilateral posterior axillary line, preferably below the 11th rib to avoid entering the thorax. A subcostal approach is most comfortable for patients.
a. To avoid bleeding complications, the needle path to the kidney should be along “Brodel bloodless line” (Fig. 53.3). This path, typically 30 to 45 degrees with respect to the table, surface should also avoid other interpositioned structures such as the liver and colon. Ideally, a posterior lower zone calyx should be targeted.
b. If the PCN is being placed for treating stones, the choice of the calyx for entry is critical and should be selected for optimal access to the stone.
c. A direct posterior entry is only useful for opacifying the collecting system; this approach should not be used to place a catheter as it is uncomfortable for the patient and leads to catheter kinking and poor function.
 FIGURE 53.3 • Cross-section of kidney showing needle pathway through Brodel avascular line and the relationship of the anterior and posterior divisions of the renal artery to the renal pelvis and infundibula. Plane of arterial division is the least vascular area of the kidney and is usually the place where nephrostomy punctures are performed to avoid damage to large vascular structures. (Redrawn from Hunter DW, et al. Percutaneous urologic techniques, ch 15, part 1. In: Castaneda-Zuniga WR, Tadavarthy SM, eds. Interventional Radiology. 2nd ed. Baltimore: Williams & Wilkins; 1992:787.) |
d. Direct puncture into the renal pelvis for the purpose of catheter placement should be avoided due to the risk of bleeding.
4. Administer local anesthesia (1% lidocaine) at the chosen skin entry site.
5. Make a small skin incision through the dermis to facilitate catheter passage.
6. Commonly used introduction systems include the Cope, Jeff, or Neff (Cook, Bloomington, IN) and AccuStick (Boston Scientific, Marlborough, MA) sets that allow initial access with a skinny (21-gauge or 22-gauge) needle and subsequent placement of 0.035-in. or 0.038-in. guidewire through a coaxial 6 Fr. introducer.
a. During gentle respiration, advance the skinny needle toward the intended calyx using either fluoroscopic or ultrasound guidance (Fig. 53.4A).
(1) Ultrasound guidance is preferred when there is hydronephrosis.
(2) Fluoroscopic guidance is more appropriate when radiopaque landmarks (e.g., calcified stones, surgical clips, indwelling ureteral stent) are present.
