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Blackwell Science, LtdOxford, UKBJUBJU International1464-410XBJU InternationalNovember 2003927

Review Article

CHOOSING A NEPHROSTOMY TUBEE.M. PAUL

et al.

Choosing the ideal nephrostomy tube

E.M. PAUL, R. MARCOVICH, B.R. LEE and A.D. SMITH

Long Island Jewish Medical Center, Department of Urology, NY, USA

Accepted for publication 3 June 2003

state of the kidney and patient at the end of the operation. Percutaneous renal surgery has the potential for significant complications during and after the procedure [5,6]. For the purposes of this review, we classify these cases as routine, problematic and complicated, i.e. respectively: no mucosal damage, minimal bleeding and stone-free; mucosal perforation, residual stones, oedema of the PUJ; and PUJ tear, significant haemorrhage, injury to adjacent organs and stenotic calyceal infundibulum. These three categories should be considered during the following discussion of the various types of nephrostomy tubes and their applications.

ROUTINE DRAINAGE FOR URINARY OBSTRUCTION

PIGTAIL CATHETERS

Pigtail catheters, the smallest nephrostomy tubes available (5–14 F), are excellent for simple drainage. The distal pigtail design prevents accidental dislodgement. The catheter tip shape is maintained by the tube’s inherent memory but the tip can be unintentionally withdrawn from the renal pelvis during patient movement, especially if the tube is not fixed to the skin. The Cope loop is one form of pigtail catheter and has a Nylon string affixed between the last side hole and the catheter tip. This functions as a self-retaining mechanism to avoid tube dislocation during patient movement or repositioning. Tension placed on the string secures the pigtail in a tight coil after tube insertion. To facilitate removal, this ‘lock’ must be released to uncoil the stent, thereby allowing it to be withdrawn.

Maheshwari

et al.

[4] reported better patient tolerability of pigtail catheters over larger tubes after percutaneous surgery. Pigtails may be used for therapeutic intrarenal infusions, and may be capped and secured to the flank between sessions. Their smallness makes them ideal for children but the Cope loop requires a relatively large renal pelvis or calyx to be positioned, as the Nylon string-locking

mechanism can lacerate renal parenchyma in a small, undilated system. This problem is worsened if the string is not pulled during insertion and fully released before removal (Fig. 1). Except for the Cope loop, the diameter of the distal pigtail is not significantly altered by increasing the size of the tube.

Because of their small calibre pigtail catheters may not be ideal if blood clots, mucus, or stone fragments are expected to pass. Similarly, their 15 G side holes have a higher propensity to occlude than larger catheters. Encrustation may prevent uncoiling of the loop, and repeat nephroscopy requires repeat dilatation. Simple pigtail catheters with no locking device may be problematic in obese patients. Movement of a large pannus may place significant tension on the catheter, thereby extracting the catheter from the renal pelvis, because of the anchoring suture on the skin. The self-retaining mechanism of the Cope loop obviates the need for further intervention to prevent accidental dislodgement.

A pigtail tube is best used after uncomplicated percutaneous renal surgery, as temporary urinary drainage of an obstructed system, for drug infusion therapy, or after surgery in children.

DRAINAGE AFTER UNCOMPLICATED PCNL

Nephrostomy tube size is a major consideration, as this one factor may have the greatest effect on patient comfort. The potential degree of injury to renal parenchyma may also be a function of tube size and should be considered when choosing an ‘ideal’ tube.

Attempts have been made to popularise techniques of ‘mini-percutaneous nephrolithotomy’ in the hope of decreasing the morbidity associated with larger nephroscopes and tubes [7,8]. Chan

et al.

[8] described their experience using PCNL with a 13 F nephroscope, followed by placing an 8 F nephrostomy tube with a 7 F double-pigtail ureteric stent. The stone-free rates were

KEYWORDS

nephrostomy tubes, percutaneous renal surgery, endourology, drainage systems,

nephrolithotomy

INTRODUCTION

The use of nephrostomy tubes in urology has become routine after percutaneous nephrolithotomy (PCNL) and for decompression of an obstructed kidney. Goodwin

et al.

[1] first described the use of percutaneously placed nephrostomy tubes in 1955, passing various sizes of polyethylene tubing over 10–14 G needles. The first nephrostomy tube described, a 14 F rubber catheter, had been used as a splint for open intubated ureterotomy [2,3] over a decade previously. A plethora of old and new designs was subsequently introduced for percutaneous drainage, including Foley, Malecot, Councill, Cope loops, circle tubes, Kaye tamponade catheters, re-entry tubes and percutaneous endopyelotomy stents.

Each tube has unique characteristics which may make its use optimal in a given clinical setting (Table 1). Regardless of its specific purpose, an

ideal

nephrostomy tube should have excellent biocompatibility and strength, be well tolerated by the patient, resist obstruction or dislodging, and be simple to insert and replace. The purpose of this review is to survey the available nephrostomy catheters, with the specific characteristics of each, to provide urologists with information necessary to optimize the use of the tube to the clinical situation.

Nephrostomy tubes range from 5 to 32 F; smaller tubes have a higher propensity to become obstructed than larger catheters, while larger tubes cause more discomfort [4]. Various tube materials are available, including polyurethane, polyethylene, silicone, Silitek

TM

, C-flex

TM

and Percuflex

TM

.

The choice of nephrostomy tube is based on the degree of procedural complexity, and the

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impressive, although the stone burden in their series ranged from 0.3–2.0 cm

2

. Visibility with the smaller nephroscope was hindered with larger stones. This study made the important assumption that smaller instruments and tubes are associated with less morbidity. However, Joshi

et al.

[9] reported more discomfort from double-pigtail ureteric stents than from nephrostomy tubes. If this is indeed the case, the ‘mini-perc’ technique provides no benefit over standard percutaneous instrumentation. If the use of a double-pigtail ureteric stent could be eliminated in ‘mini-perc’ surgery, this approach might be important in percutaneous stone procedures. The same could be said for the ‘tubeless’ approach, discussed later.

Another potential effect of tube size are the theoretical adverse effects on renal function. Animal and human studies have consistently shown no detrimental effect on short- or long-term renal function after PCNL or shock-wave lithotripsy (SWL). Lechevallier

et al.

[10] found less renal scarring associated with PCNL than with SWL. As SWL caused more renal trauma than PCNL, perhaps nephrostomy tube size alone was unlikely

to contribute significantly to the degree of renal damage. Wilson

et al.

[11] found that nephrostomy tube insertion with tract dilatation to 24 F caused more scarring than SWL. Histological examination of the kidneys revealed that the maximum injury produced was <2% of total kidney volume. Given that percutaneous tracts are generally larger than the tubes used to drain them, it is unlikely that the nephrostomy tube alone bears much responsibility for renal scarring. Regardless, as it has been shown that scarring does not translate to any degree of clinical renal dysfunction, the choice of tube size need not be unduly influenced by this consideration.

BALLOON RETENTION CATHETERS

Balloon retention catheters include the Foley, Councill, Couvelaire and Argyle; the most commonly used is the Councill, because it is easy to insert and exchange over a guidewire. Balloon retention tubes are typically 12–32 F, although the Councill is only available as >16 F. The balloon is an effective retaining mechanism, and the larger diameter catheters allow for drainage of urine that may be mixed with blood, mucus, or debris, and may provide

tamponade of renal haemorrhage. A terminal hole can be created in a Foley with either a hole punch or a 14 G needle, after which a wire can be threaded through the tip. Because of the ease of guidewire exchange, nephroscopy can be repeated through the existing tract. These catheters have two drawbacks; first, the balloon has the potential to occlude one or more calyces [12], and second, it may be a source of discomfort to the patient, so over-inflation should be avoided.

MALECOT TUBES

Malecot tubes represent an alternative to balloon retention catheters, obviating the concern for renal calyceal obstruction by using a mushroom-style tip. Because there is no balloon port, a smaller catheter can be used to achieve equally effective drainage. Their self-retaining mechanism is less secure than that of balloon catheters and Cope loops. For this reason several different modifications have been made to improve anchoring to the renal pelvis, including a suture-locking mechanism [13], an ‘accordion catheter’ [14], and an Amplatz anchor catheter [15].

Malecot tubes provide large-bore drainage after percutaneous renal surgery, and allow for repeat nephroscopy. These catheters are typically fixed to the skin with nonabsorbable suture but this may allow dislodging of the catheter with pannus movement in obese patients.

TUBELESS PERCUTANEOUS SURGERY

A successful ‘tubeless’ approach to PCNL and antegrade endopyelotomy has been described [16,17], using double-pigtail ureteric stents rather than nephrostomy tubes. In a preliminary study, in select circumstances, this approach was safe, cost-effective and well-tolerated [17].

Feng

et al.

[18] found that the tubeless approach was less morbid and more cost-efficient than standard or ‘mini-perc’ PCNL. However, they used double-pigtail ureteric stents in their series to provide internal drainage, which may cause more discomfort than nephrostomy tubes [9]. As nephrostomy tubes can be routinely removed before discharge from hospital, a tubeless approach with a ureteric stent affords more discomfort in the long-term than the alternatives. The comparative study by Feng

et al.

[18] also

TABLE 1

Currently available nephrostomy tubes and their specifications

Type of nephrostomy tube Diameter, F Lengths, cm Materials

Microvasive

Pigtail (

±

locking mechanism) 8–14 25 Percuflex (optional dissolvingFader Tip), C-Flex

Malecot 14–24 35 C-FlexLocking Malecot 8–14 30 PercuflexRe-entry 14–24/6–8 30 (17 tail) C-Flex

Cook

Pigtail (

±

locking mechanism) 5–14 15 (paediatric)

-

30 Polyurethane, UltrathaneMalecot 8–14 25.5–30 Polyethylene, polyurethaneRe-entry 8.3–24/5–7 30 (with 20 tail) PolyvinylchlorideEndopyelotomy 10–22/4.7–8.2 27 (26 distal seg) Polyurethane

ACMI

Pigtail 8.5–14 – Silitek

Mentor

Circle 12–22 N/A Silicone

Bard

Councill 12–24 – Latex

Rusch

Pigtail 6–8 30 Wiruthane (thermoplasticurethane elastomer)

Malecot 10–40 35 LatexBalloon-type with ureteric tail 12–24/4–8 75 Silicone(Endopyelotomy) 10–12 22.5–34.5 Wiruthane

Bentec Medical

Circle tube 8–30 N/A Silicone

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FIG. 1.

Configuration and size of the renal pelvis is an important consideration when choosing a nephrostomy tube. (A) Small, bifid renal pelvis. (B) 10 F Cope loop catheter inserted into collecting system of A over a guidewire. (C–E) The loop cannot be formed by pulling on the string in the usual manner because of the size and configuration of the collecting system. A balloon-retention or Malecot catheter would have been a better choice in this patient.

A B

C D

E

found ‘mini-percs’ to provide no advantages over the standard technique, and confirmed poorer visibility with the smaller nephroscopes.

The authors routinely place a nephrostomy tube at the end of surgery. On the second day, a contrast nephrostogram is taken, specifically to confirm the absence of residual stones, obstruction or contrast medium extravasation before tube removal. This regimen serves several purposes. First, there is a substantial risk of bleeding in many percutaneous cases, especially in those with large stone burdens. With the growing use of ureteroscopy, patients who ultimately need PCNL often have sizeable stones. Although bleeding after percutaneous surgery is typically self-limited, we consider that adequate drainage is necessary to avoid ureteric obstruction and perirenal extravasation of blood and urine. Additionally, persistent bleeding will be recognized sooner with a nephrostomy tube in place and may be more easily treated. The alternative approach risks a significant retroperitoneal bleed. Furthermore, in patients with large stone burdens, residual calculi may be unrecognized at the end of surgery. With no nephrostomy tube, repeat nephroscopy necessitates a fresh renal puncture. For these reasons it is prudent to leave a nephrostomy tube in place at the end of surgery and monitor its drainage. If there is significant haemorrhage the tube may be clamped to tamponade the bleeding [19]. If the patient remains stable and bleeding ceases, the tube is typically unclamped the next morning. If no further bleeding is encountered the nephrostogram is taken on the following day. If all is well the tube is removed (or, in the case of an endopyelotomy, clamped), and the patient discharged home later that day. The size and type of tube chosen depends on the degree of surgical complexity and the appearance of the draining fluid.

The concept of tubeless surgery has not yet gained acceptance. There are now several reports of tubeless surgery, the largest of which comprised 112 patients [20]. The conclusion of these studies has been that tubeless surgery may be safe and effective in selected patients. However, importantly, these patients met strict inclusion criteria, and their average stone burden was relatively low. They were left with no

external

tubes, but internal ureteric stents, which can cause significant discomfort, were still necessary. Goh

et al.

[21]

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described a variation of the tubeless approach, using an externalized ureteric catheter instead of an internal stent. This study was small and excluded patients with large stone burdens, but showed a trend to decreasing morbidity while preserving surgical safety and efficiency. However, there were two patients left with small residual stone fragments. Further studies may prove that this technique decreases pain, hospital stay and overall costs of percutaneous renal surgery, in selected cases.

With rapid advances in endourology there is no doubt that we will continue to find more efficient approaches to ensuring complete stone retrieval, while inflicting less renal damage. As techniques and equipment improve, there is no question that success rates, costs and patient comfort will also improve. At present the use of a ‘tubeless’ approach may still be premature. However, in patients with minimal bleeding at the end of surgery, and in whom there are no plans for repeat nephroscopy (routine percutaneous renal surgery), there may be an indication for this approach.

DRAINAGE AFTER PROBLEMATIC PCNL

There is potential for significant haemorrhage during or after percutaneous renal surgery. Reported transfusion rates are 0.43–23% [6,22] and the need for angio-embolization is

ª

0.8% [19]. Strategies for controlling this complication include observation and bedrest with nephrostomy tube drainage, clamping of the nephrostomy tube to tamponade bleeding, and selective embolization of the feeding blood vessels [23].

BALLOON RETENTION CATHETERS

Different nephrostomy tubes have been described for dealing with haemorrhage, all with some variation of a balloon tamponade mechanism [24–27]. The Kaye Tamponade catheter has a 15-cm long, 36 F balloon which surrounds the length of the tube, thereby functioning to tamponade the nephrostomy tract while simultaneously draining the renal pelvis [27]. The haemostatic Malecot tamponade catheter described by Laor

et al.

[25] uses the same concept, with the novel addition of a Malecot tip for anchoring purposes. The alternatives all use conventional balloon retention catheters in a fashion suitable for tamponading renal

haemorrhage. There have been reports of renal vein perforations during percutaneous renal surgery, which have been similarly managed with balloon tamponade [28]. The technique described under these more complicated circumstances involves inflating a Councill-tip catheter in the renal pelvis at the site of renal vein perforation, confirming adequate tamponade by the lack of further extravasation of contrast medium into the vein.

The uses of a balloon retention catheter for controlling PCNL complications are not limited to haemorrhage alone. Gerspach

et al.

[29] described a treatment algorithm using a Councill catheter for colonic drainage after perforation during percutaneous surgery. Although a rare occurrence, when colon perforation is recognized during surgery it is important to separate the gastrointestinal and urinary tracts to prevent fistula formation. A balloon catheter is inserted through the nephrostomy tract directly into the colon and inflated within the lumen. The kidney is drained with a double-pigtail stent or a second nephrostomy tube, and laparotomy may be avoided.

Balloon retention catheters are appropriate in routine, problematic and complicated cases. They may be used when repeat nephroscopy is expected and for cases in which the drained fluid may be more viscous than urine, or may contain particulate matter. In addition, although described as a utility of re-entry catheters, these tubes are useful for maintaining a large access port after dilatation of a stenotic infundibulum or fulguration of a calyceal diverticulum [30], and to radiographically guide further percutaneous access, such as before inserting a circle loop [31]. They provide large-bore drainage after any form of problematic renal surgery, allowing for healing of injured mucosa.

DRAINAGE AFTER COMPLICATED RENAL SURGERY

RE-ENTRY TUBES

The most popular Malecot is the re-entry tube, first described by Khasidy and Smith [32]. This catheter is manufactured from C-flex and is unique because it can be reinserted if serious bleeding is recognized

during

tube

removal [19]. These tubes are available as 8–24 F in their proximal segments. Extending from the Malecot portion of the catheter is a 17 or 18-cm extension of 5–8 F, which is advanced into the ureter, preserving ureteric access should it become necessary later [32]. If injury to the PUJ is recognized during nephrolithotomy, or there is PUJ oedema on the nephrostogram, these catheters also provide effective PUJ stenting. Disadvantages include the lack of a strong self-retaining mechanism and the fixed length of the 17 or 18-cm tail. Depending on the patient’s height, the tail may extend all the way to the vesico-ureteric junction, thereby causing discomfort.

The ideal use for re-entry tubes is most commonly in situations in which large-bore drainage is needed and where tamponade of the tract may be necessary. Similar to balloon retention catheters, these tubes provide effective drainage after problematic and complicated percutaneous surgery, and they allow for repeat nephroscopy. They are typically fixed to the skin with a nonabsorbable suture but this may allow dislodging of the catheter with pannus movement in obese patients. If the catheter is displaced reinsertion under fluoroscopy is easy.

ENDOPYELOTOMY STENTS

Endopyelotomy stents are in a class of their own; these nephrostomy tubes are typically made from polyurethane, Percuflex, C-flex or silicone. One variation of this tube is the Smith endopyelotomy stent. Although there are various sizes of endopyelotomy stents available, the Smith stents are 14 F proximally and taper to 8 F distally, where they coil in the bladder. They are designed to maintain the patency of a recently incised PUJ while simultaneously providing external drainage for the kidney if there is persistent obstruction after surgery. If a ureteric stone is extracted via an antegrade approach, these tubes serve to provide renal drainage in addition to ureteric stenting. The advantage of these stents over the conventional nephrostomy tube in combination with a JJ endopyelotomy stent is the ability to remove the nephrostomy tube together with the ureteric stent, thereby avoiding an additional cystoscopic procedure. It obviates the concern of the endopyelotomy stent migrating out of position, leaving the surgical site unstented. In addition, the combination of a separate

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nephrostomy tube plus ureteric stent often warrants fluoroscopic monitoring during nephrostomy tube removal, to avoid unintended removal of the stent. If the patient develops fever or flank pain, the nephrostomy portion of this catheter can be opened, allowing for urinary drainage if there is a potentially persistent obstruction. For patients with BOO secondary to prostatic enlargement, postoperative removal of the Foley catheter may lead to urinary retention. Because endopyelotomy stents promote reflux of urine, in patients unable to void after bladder catheter removal the option exists to leave the nephrostomy tube to drain while the patient regains his ability to void spontaneously [33]. One drawback of this combination unit is that it must remain in place until the surgeon is certain that the entire unit is ready to be removed (6–8 weeks). In addition, the distal coil of these tubes may cause bladder irritation, much like internal endopyelotomy stents or double-pigtail catheters.

The use of a 27 F wound drain advanced over a percutaneous 14/8.2 F endopyelotomy stent was recently assessed and compared with endopyelotomy stents alone [34]. This drain was intended to assist with PUJ stenting, to achieve a funnel-shaped PUJ after healing. This study reported impressive outcomes with the 27 F stent, with fewer long-term failures than with a standard Smith endopyelotomy stent. These results may ultimately change the standard of care for antegrade endopyelotomy stenting, but the findings require confirmation in larger studies.

Endopyelotomy stents are ideal nephrostomy tubes for urinary drainage and stenting of the PUJ after an endoscopic incision or antegrade ureteric stone-basketing procedure, and for stenting a stenotic infundibulum or neck of a calyceal diverticulum, all of which can be considered complicated percutaneous renal surgery.

CIRCLE TUBE (U-LOOP)

Representing an atypical nephrostomy tube, these silicone rubber tubes enter the kidney through one calyx and exit via another. First popularized for percutaneous use in 1979 [35], U-loop nephrostomy tubes have a unique design that allows for simple tube exchange over a guidewire, and ease of irrigation. They facilitate easy drainage of even the smallest of renal pelves, and require

less frequent changes, as their multiple side-holes and silicone design help resist encrustation and infection. Circle tubes are particularly useful for stenting across regions of infundibular stenosis, and may be left in place long-term. Although more cumbersome than standard nephrostomy tubes, they are useful in situations that would otherwise warrant two separate catheters.

CONCLUSION

Establishing an

ideal

nephrostomy tube is a goal which may not be feasible; no single tube has all of the advantageous properties of the available alternatives. However, the search for the ideal tube

for a given purpose

may be a realistic endeavour (Table 2). Being informed of the various designs and of the different indications for the multitude of existing drainage devices will give urologists more confidence in appropriately matching the tube to the clinical task at hand.

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TABLE 2

Choosing the ideal nephrostomy tube

Indication Ideal nephrostomy tubeDrainage of obstructed system PigtailUncomplicated PCNL Balloon, Malecot, tubelessProblematic PCNL Councill, Kaye TamponadeMinor mucosal damage to PUJ

or ureterRe-entry, endopyelotomy

Pyelopyelostomy, two areas ofinfundibular stenosis

Circle

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Goldfischer ER, Eiley DM, Smith AD.

Novel hemostatic nephrostomy tube.

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Correspondence: E.M. Paul, Long Island Jewish Medical Center, Department of Urology, New Hyde Park, NY, USA.e-mail: eliepaul@yahoo.com

Abbreviations: PCNL, percutaneous nephrolithotomy; SWL, shock-wave lithotripsy.