CHAPTER 23 Urologic and genital systems

Matthew Kogut, Todd L. Kooy, Steven B. Oglevie

Genitourinary interventional radiology has evolved with the advances in knowledge and technology. With vast improvements in the diagnostic capabilities of noninvasive imaging, purely diagnostic catheter-based imaging studies are performed infrequently. Although many of the genitourinary interventions have been performed for decades, the procedures have been refined with new equipment and continuous improvements in imaging guidance. Various percutaneous drainage procedures involving the urinary collecting system remain necessary tools for the interventionalist. However, collaboration with urologists, transplant surgeons, obstetricians, and gynecologists has also allowed us to hone advanced techniques and expand into new areas such as renal transplant interventions and transcervical sterilization via fallopian tube occlusion.

Percutaneous nephrostomy (online cases 24 and 36)

Anatomy

The kidneys are retroperitoneal organs surrounded by perinephric fat and enclosed by Gerota fascia. Their axes parallel the psoas muscle so that the upper pole is medial and slightly more posterior than the lower pole. During normal development, the kidney ascends and rotates medially about its vertical axis such that the renal hilum is directed anteromedially at an angle of approximately 30 degrees from the horizontal plane.

The main renal artery and vein lie anterior to the renal pelvis. However, a posterior branch of the renal artery courses behind the renal pelvis to supply the dorsal segments. A percutaneous nephrostomy (PCN) track extending directly into a calyx has the least chance of causing substantial arterial injury (Fig. 23-1). Punctures into an infundibulum or directly into the renal pelvis carry a higher risk of hemorrhagic complications, because larger arterial branches may be traversed. Direct renal pelvic punctures also risk the formation of a urinoma after the tube is removed.

Figure 23-1 Posterolateral approach to posterior calyx for percutaneous nephrostomy. This approach is advantageous because it minimizes the risk of arterial injury and provides a straight vector for advancement of guidewires, dilators, and catheters into the renal pelvis. The track is lateral enough to avoid the paraspinal muscles but not so lateral as to risk colon perforation.

The calyces are usually arranged in anterior and posterior rows. At the upper and lower poles, fusion can result in compound calyces. During urography in the anteroposterior projection, classic teaching is that posterior calyces are located medially and seen en face, while anterior calyces are located more laterally and seen in profile. However, a recent evaluation of calyceal anatomy on computed tomography (CT) showed that this is not the case in the lower pole. Most lower poles have two to three calyces and the most posterior calyx was often more lateral.¹ However, normal variation occurs, which is why, with the patient in prone position, oblique imaging, ultrasound, or injection of air is recommended to identify posterior calyces. Discrimination between the anterior and posterior calyces is critical, because posterior calyces are strongly preferred for most PCN procedures.

Understanding the normal and variant relationships of the kidneys with surrounding structures is important for safe and successful placement of a PCN.² The descending colon lies in the anterior pararenal space, and its relationship to the left kidney is determined by the position of the lateroconal fascia. In approximately 10% of patients, the descending colon lies behind a horizontal line at the posterior edge of the left kidney. In about 1% of cases, the descending colon extends behind the left kidney.³ Rarely, the ascending colon lies posterolateral to the right kidney and medial to the liver.

The pleura extends posteriorly down to the 12th vertebral body and then extends laterally, crossing the 12th, 11th, and 10th ribs. Although great normal variation occurs, about one half of the right kidney and one third of the left kidney lie above this posterior reflection of the pleura.

The liver is anterolateral to the upper pole of the right kidney. In some patients, a portion of the right lobe of the liver may extend posterolaterally to the upper pole of the kidney. The position of the spleen is more variable. It typically lies superolateral to the kidney but often is adjacent to the lateral margin and frequently may be posterolateral to the upper pole. Because of these variants of colonic, hepatic, and splenic anatomy, review of prior cross-sectional imaging studies is critical before PCN.

Patient selection

The indications for PCN fall into four broad categories (Box 23-1). Each patient must be considered individually, because some have both indications for and contraindications to the procedure. The decision about whether to perform PCN depends on the details of the particular situation and on the other available options.

Relief of urinary obstruction

The most common indication for PCN is relief of urinary obstruction. Imaging studies should be performed to demonstrate dilated collecting systems, and they usually delineate the anatomic level of obstruction and the cause. The ureteral obstruction may be acute, as with obstructing ureteral calculi or traumatic ureteral injury. However, the obstruction may be long-standing, as with primary urothelial neoplasms, extrinsic compression, or direct invasion by retroperitoneal or pelvic malignancies.

In patients with bilateral obstruction or with obstruction of a solitary kidney, PCN is indicated for preservation of renal function. In some patients with widely disseminated malignancies and very short life expectancies, decompression may not be indicated. Many oncologists believe a uremic death is a reasonably painless way for a terminal patient to die. This decision must be addressed individually and tailored to the desires of the patient and his or her family.

In patients with acute unilateral ureteral obstruction, decompression is justified to preserve renal function on the affected side. Long-standing obstruction is associated with an irreversible deterioration of renal function and parenchymal atrophy. Although the patient’s serum blood urea nitrogen and creatinine levels usually do not become elevated with unilateral obstruction, the damage to the ipsilateral kidney is progressive and irreversible when not addressed promptly. Decompression with PCN may allow the cause of acute ureteral obstruction to be addressed on a more elective basis without risk of losing renal function.

In any patient with obstruction and suspicion of infection, emergent decompression is indicated. Infection may be suggested by fever, leukocytosis, flank pain, or sepsis. These patients must also be treated immediately with appropriate intravenous (IV) antibiotics and hemodynamic support as needed. The decompressive procedures in patients with pyonephrosis must be conducted and monitored with care, because the septic condition may be worsened with the intervention.

Patients with chronic unilateral hydroureteronephrosis due to malignancy do not necessarily require decompression unless infection is suspected. In the absence of malignant disease, kidneys with an estimated renographic glomerular filtration rate (GFR) of greater than 10 mL/min/1.73 m ² will likely stabilize or improve renal function, while kidneys with worse function may not be worth salvage.⁴ The finding of mild or moderate cortical atrophy on CT or ultrasound is not a reliable predictor of limited potential for functional recovery after a PCN. In fact, decompressive PCN may be indicated to assess the recoverable function of a chronically occluded kidney.

Diversion of urine

PCN is used to divert urine in cases of urinary leakage (Fig. 23-2). PCN, usually in combination with ureteral stent placement, allows most ureteral injuries to seal. The stent is thought to serve as a scaffold for ureteral healing. Percutaneous drainage of associated urinomas that accumulated before urinary diversion also may be performed. In cases of malignant or inflammatory fistulas, PCN is indicated to divert urine in conjunction with stent placement. PCN has been used also to divert urine and treat patients successfully with hemorrhagic cystitis.⁵

Figure 23-2 Decompression of a duplicated collecting system to assist in healing an anastomotic leak between the ureters and neobladder. A, Computed tomography shows the duplicated ureters near the anastomosis (circle) adjacent to dilute contrast seen in a large urinoma (arrowhead). The neobladder (arrow) opacified with contrast is partially seen. B, A percutaneous nephrostomy has already been placed into the upper pole moiety (arrow). Access has been gained to a posterior calyx (arrowheads) in the lower pole. The calyx is outlined by air, which was injected to confirm a posterior location. C, The upper moiety is now decompressed (arrowheads). The more inferior nephrostomy was injected with contrast to confirm appropriate location, with the pigtail now formed in the lower moiety renal pelvis (arrow).

Access for diagnostic interventions

Percutaneous access may be performed to permit antegrade pyelography. However, advances in diagnostic radiology dominated by CT and magnetic resonance (MR) urography have rendered this indication extremely rare.⁶ Biopsies of urothelial lesions may be performed through nephrostomy access using brushes and forceps. Nephrostomy access may be used for diagnostic nephroscopy and ureteroscopy. Functional studies (e.g., Whitaker test) can be performed to determine the significance of urographically detected stenoses and to assess the results of interventions such as endopyelotomy or balloon ureteral dilation. This procedure is typically reserved for complicated cases in which nuclear scintigraphy or MR urography fail to give adequate physiologic information.⁷ MR urography may become the “one-stop shop” for anatomic and functional information regarding the genitourinary system.

Access for therapeutic interventions

Ureteral strictures may be dilated percutaneously, and ureteral stents can also be placed. Foreign bodies (e.g., encrusted or occluded ureteral stents) may be retrieved through the nephrostomy access (Fig. 23-3). Stone therapy can be performed by chemodissolution or mechanical fragmentation and extraction. Antifungal agents may be infused directly through the nephrostomy tube to treat fungus balls in the upper urinary tract.⁸^,⁹ Nephroscopically guided operations can be performed, including resection of urothelial neoplasms and endopyelotomy. Intracavitary adjuvant chemotherapy can be administered through a nephrostomy in certain cases of transitional cell carcinoma.¹⁰

Figure 23-3 Percutaneous nephrostomy for retrieval of a broken internal ureteral stent. A, There is a sheath in position over a “safety” wire. A snare (arrow) has been placed around the proximal aspect of the broken stent (arrowheads).B, The snare (long arrow) is secured around the stent, which is being pulled out of the sheath. Short arrows mark the distal aspect of the stent and the arrowhead indicates the “safety” wire.

Access provided for stone treatment is one of the most common indications for PCN placement. By the age of 70 years, 11% of men and 5.6% of women will have a symptomatic urinary tract stone.¹¹ Although stones smaller than 5 mm often pass without intervention, stones between 5 and 10 mm have variable outcomes, and stones larger than 10 mm will not pass without intervention.¹¹ Many renal calculi can be managed successfully with extracorporeal shock wave lithotripsy (ESWL) or percutaneous nephrostolithotomy (PCNL), with success rates that rival open surgery but with significantly less morbidity, recovery time, and cost.

Planning the approach and entry site is the most critical step of the PCNL procedure and should be made by consultation between the urologist and interventional radiologist. The puncture site must allow the stone to be accessed and removed but not be made directly into the pelvis or infundibulum. This is one of the situations where occasionally supracostal access and/or access to an anterior calyx is optimal for future treatment (Fig. 23-4). If the initial puncture site is not ideal, it is better to make a new puncture in a more suitable position than to proceed with track dilation through which the stone cannot be removed. The best approach depends on several factors, the most important of which is the location of the stone burden.

Figure 23-4 Access for percutaneous nephrolithotomy (PCNL). After consultation with the urologist, the best approach was deemed to be supracostal and lateral, targeting an anterior midpole calyx containing a stone. A, Initial fluoroscopic guided puncture directed at the midpole stone (arrow).B, A DynaCT was performed on the fluoroscopic table after initial puncture to confirm a safe approach into the calyx that avoided the colon. An arrowhead shows the supracostal approach and the arrow indicates the fat plane between the track and colon. C, Access was confirmed to be along the course of the stone (arrowhead) and a 0.018-inch wire (arrows) is coiled in the renal pelvis around the larger stone. D, Final spot image shows the nephrostomy pigtail formed in the superior aspect of the renal pelvis. A 5-Fr angled catheter (arrowheads) also traverses the stone down the ureter, terminating in the bladder. This ureteral catheter provides stable access for the urologist.

Contraindications

Contraindications to PCN include uncorrectable coagulopathy and an uncooperative patient. If hyperkalemia is severe (i.e., potassium level greater than 7 mEq/L), hemodialysis should be performed to correct the electrolyte balance before the procedure.

Surgical and medical alternatives

It usually is advantageous to initially consider a retrograde approach for renal drainage in patients with obstructive uropathy. PCN is typically reserved for patients in whom retrograde attempts are unsuccessful or not feasible. Although retrograde stents need routine changes and management, the patient will not have an external tube to manage. A “surgical” nephrostomy may be placed during open surgery directly into the renal pelvis, but this is rarely indicated because PCN can be performed safely and effectively in almost all patients (Fig. 23-5). Medical therapy for obstructive uropathy is limited. In some patients with widely disseminated malignancy or retroperitoneal fibrosis and obstructive uropathy, renal function may improve with the administration of corticosteroids.¹²^,¹³

Figure 23-5 Surgical nephrostomy. A Foley catheter (arrowheads) directly enters the renal pelvis. Such open surgical nephrostomies are rarely indicated unless another open procedure is being performed at the same time.

Technique

Preprocedure care

Before the procedure, patients should be screened and treated for any coagulopathy. Review of any prior abdominal imaging is indicated to detect variant anatomy of colon, spleen, and liver, which should be considered when selecting the nephrostomy approach.

Prophylactic antibiotics should be administered intravenously before the procedure. The most common urinary tract pathogens are Escherichia coli, Klebsiella, Enterococcus, Proteus, and Staphylococcus species.¹⁴ For prophylaxis in the absence of any overt infection, a third-generation cephalosporin or a fluoroquinolone is usually chosen. Ciprofloxacin is commonly used in both oral and IV forms. When infection exists, therapy is directed toward the isolated organisms. Another option for broad coverage would be ampicillin with gentamicin.¹⁴^,¹⁵

Procedure

The patient is typically placed in the prone or oblique prone position on the interventional radiology (IR) table. In critically ill patients or pregnant patients who are unable to be placed prone, the procedure can be performed with the patient in a supine oblique position.

The initial puncture for PCN is performed with ultrasound, fluoroscopy, or very occasionally with CT imaging. Ultrasound is the optimum modality. A suitable calyx can be selected and entered with continuous sonographic guidance while avoiding surrounding organs (Fig. 23-6). Fluoroscopy can be used when renal function permits the IV administration of contrast material and results in satisfactory opacification of the collecting system. Fluoroscopy also may be used to puncture directly onto a radiopaque calyceal calculus (see Fig. 23-4). If a retrograde ureteral catheter has been placed, it may be used to opacify the collecting system. CT guidance for puncture occasionally may be required in patients with congenital anomalies (i.e., horseshoe or pelvic kidneys) or issues with body habitus or positioning (e.g., severe scoliosis, morbid obesity) (Fig. 23-7).

Figure 23-6 Ultrasound guidance used for initial puncture during decompressive nephrostomy. Arrows show the course of the needle into a dilated posterior lower pole calyx. Adjacent structures can be identified and avoided with ultrasound.

Figure 23-7 Computed tomography–guided placement of a percutaneous nephrostomy in an obese patient in the supine position. The patient would not tolerate a prone position. A, A grid is on the patient’s skin. An arrowhead indicates the renal pelvis and the arrow is on the targeted dilated calyx. B, The needle (arrow) has been placed into the calyx and a 0.018-inch wire (arrowheads) is coiled in the renal pelvis. C, The nephrostomy is in place, and a small amount of hemorrhage (arrow) is seen along the track.

Planning the puncture pathway is the most crucial step in PCN placement because poorly placed punctures are associated with higher complication rates and may preclude successful completion of subsequent interventions. For a simple decompressive nephrostomy, puncture of a lower pole calyx is satisfactory. This approach minimizes the risk of pleural complications. If ureteral stent placement is planned, puncture of an interpolar calyx is preferable to create a gentle curve down the ureter. However, ureteral stents usually can be placed from an inferior polar approach using stiff guidewires and sheaths. Access through an upper pole calyx is required occasionally for stone extraction. In this case, the track is occasionally intercostal, and pleural complications are more frequent.

The ideal skin entry site is at least 12 cm lateral to the midline but medial to the posterior axillary line. If the skin entry site is too medial, the paraspinal muscles are traversed, and subsequent interventions are rendered more difficult because the guidewire and catheter must abruptly turn medially on entering the calyx. A medially placed nephrostomy also is more painful for the supine patient. If the skin entry is too lateral, the risk of colonic perforation increases. However, this risk is typically very small, estimated at up to 3% when the expected path during placement of lower pole nephrostomy tube is simulated using multiplanar CT.¹⁶

A posterolateral approach, with the needle angled about 30 to 40 degrees from vertical, directly into a posterior calyx is favored (see Fig. 23-1). This route follows the relatively avascular posterolateral plane of the kidney (i.e., Brödel line). Punctures generally should be made directly into a posterior calyx (see Fig. 23-1). This choice provides a straight vector into the renal pelvis and minimizes the amount of renal parenchyma traversed by the nephrostomy track. Infundibular punctures or punctures directly into the renal pelvis should be avoided because large arteries may be traversed. Inadvertent puncture of anterior calyces makes subsequent interventions more difficult because of the tortuous pathway and increases the risk for significant arterial injury. Anterior calyces should be targeted only in the rare patient with an anterior calyceal stone (see Fig. 23-4). Oblique imaging and injection of air or carbon dioxide is helpful to determine whether a calyx punctured under fluoroscopy is posterior or anterior (Fig. 23-8).

Figure 23-8 Stepwise placement of a decompressive nephrostomy. A retrograde stent is in position, which was not adequately decompressing the system. A and B, Two different obliquities show puncture of a posterior lower pole calyx, outlined by injected air (arrowheads). The 22-gauge needle (arrow) has been connected to tubing for injection with continuous fluoroscopic observation. A 0.018-inch wire was advanced through the collecting system. C, The coaxial set (arrowhead) has been advanced over the 0.018-inch wire, which has been removed and a stiffer 0.035-inch wire (arrow) has been advanced down the ureter. D, The nephrostomy tube (arrowhead) has been advanced down the ureter over the wire. E, The nephrostomy tube has been partially withdrawn and the pigtail has been formed in the renal pelvis.

When the collecting system has been entered with a 21- to 22-gauge needle, a sample of urine should be aspirated initially for cultures. If clinical suspicion for infection is high or the urine is cloudy, opacification of the collecting system must be performed gently after evacuating an equal amount of urine. Instillation of contrast by gravity may help prevent overdistention and worsening of sepsis. Likewise, subsequent manipulations that may have been planned should be minimized until the collecting system has been adequately decompressed and urine has cleared.

The initial puncture site is carefully scrutinized before dilation and catheter placement. If instillation of contrast or air reveals the initial puncture is not into a suitable posterior calyx, the needle should be left in place to opacify the system while a new needle is guided fluoroscopically into an appropriate calyx (Fig. 23-9). After the puncture is deemed satisfactory, a 0.018-inch guidewire is advanced into the renal pelvis and ideally down the ureter. A skin nick is made along the needle track. Blunt dissection of the subcutaneous tissue is performed. A coaxial access set, such as the Accustick set (Boston Scientific), is advanced under fluoroscopic guidance over the wire into the collecting system (see Fig. 23-8C). Urine can be aspirated and contrast injected through the sidearm of some access sets. The inner portions of the access set are removed. A 0.038-inch guidewire is advanced through the outer portion of the access set into the renal pelvis or ureter. In some access sets, the 0.018-inch wire can be left alongside the 0.038-inch wire as a “safety wire.” An angled guiding catheter may help direct the guidewire down the ureter into a more secure position if necessary (Fig. 23-10).

Figure 23-9 Initial puncture (arrowheads) was into an infundibulum. This needle was left in place to inject contrast/air to guide a second needle into a lower pole calyx. A needle driver (arrow) is placed on the patient to mark the proposed skin entrance site. A small amount of extravasation is seen.

Figure 23-10 The patient needed a nephrostomy for treatment of a lower pole stone not well seen on this image. Urology requested superior pole access. The outer dilator of the coaxial set is at the access point in the posterior superior pole calyx, which is outlined by injected air (arrow). Given the steep angle of entry to the renal pelvis, an angled catheter (arrowhead) was necessary to guide the 0.035-inch wire into a more stable position before placement of the nephrostomy.

The track is then dilated, and an 8- to 12-French (Fr) locking pigtail nephrostomy catheter is placed. The pigtail is formed and locked within the renal pelvis (see Fig. 23-8E). Care must be taken to avoid forming the pigtail in the ureter or in a calyceal infundibulum. The 8-Fr tubes are satisfactory in patients with clear urine. Larger tubes may be helpful in patients with grossly purulent urine or stone debris. Locking pigtail catheters generally are preferred over other self-retaining catheters (e.g., Malecot, accordion, Foley). The nonpigtail catheters occasionally may be useful in collecting systems not capacious enough to accommodate a pigtail. In patients for whom access was provided for PCNL, a 5-Fr catheter is often left in the bladder alongside the nephrostomy tube, giving the urologist a stable access for a stiff working wire as well as access to the renal pelvis from the nephrostomy tube.

The catheter is secured to the skin using adhesive dressings or suture. Adhesive dressings minimize catheter kinking and reduce the risk of catheter dislodgment. After the track has matured, a simple dry dressing may be placed over the exit site. The catheter is left to gravity drainage with close monitoring of urine output. It typically requires irrigation only if blood clots occlude the tube.

Patients should be followed closely after the procedure for hemorrhagic or septic complications. In patients with bilateral obstructive uropathy undergoing PCN, dramatic fluid and electrolyte shifts may occur with postobstructive diuresis. In carefully selected patients, PCN may be performed safely as an outpatient procedure.¹⁷ In this situation, however, the operator should have a low threshold for admitting the patient if there is any evidence of hemorrhage, sepsis, or severe pain during or after the procedure.

Catheter maintenance

Chronic indwelling nephrostomy tubes usually should be exchanged every 3 to 6 months to prevent encrustation and occlusion. Some patients may require exchanges as often as every 6 weeks. It is better to err on the side of frequent catheter exchanges than to have the catheter occlude and have the patient develop sepsis or further deterioration of renal function due to obstruction. If the catheter is initially exchanged at 3 months and appears to be functioning well, the interval may be increased by 1 month at a time for up to 6 months.

Colonization with bacteria, fungi, or both invariably develops in patients with chronic indwelling nephrostomy tubes.¹⁸ Asymptomatic bacteremia occurs frequently (about 10% of the time) during routine catheter exchanges; preprocedural antibiotics are not successful at preventing bacteremia.¹⁹ Nonetheless, some operators routinely give antibiotics for tube exchanges, particularly when the tube has been functioning poorly. For patients with cardiac valvular disease, a full course of antibiotics should be administered before catheter exchange to minimize the risk of bacteremia. Despite therapeutic levels of antibiotics during catheter exchange, a septic reaction may still occur as a reaction to endotoxin released into the vascular system.

Patients with occluded catheters can present a challenge for catheter exchange. The pigtail catheter retention string initially should be secured so that it is not pushed down the catheter into an occlusive tangle with repeated attempts at guidewire passage. Hydrophilic guidewires are preferred for negotiating an occluded catheter. If the endhole cannot be passed, a side hole is acceptable. After the guidewire is through the catheter, the string is released to allow the loop to open. If no guidewire can be passed, a sheath may be passed over the catheter, after its hub has been cut off. The catheter can then be removed and replaced through the sheath.

Catheter dislodgment represents an urgent situation, because rapid tube replacement is required to maintain track patency. Tracks that have not had a tube replaced within 48 to 72 hours are difficult to renegotiate. All patients with PCN tubes should be educated about the urgency of this situation. After sterile preparation, the track is probed with an angled 5-Fr catheter. Contrast may be injected to define the track, and a hydrophilic wire and/or the angled catheter is then negotiated back into the collecting system.

Results

In patients with obstructed, dilated collecting systems, a decompressive PCN can be placed successfully in almost all cases. Technical success should be expected in greater than 95% of cases.²⁰^,²¹ In nondilated collecting systems or complex stone cases, technical success may decrease to 85% or less.

The clinical response to PCN by patients with urosepsis often is dramatic. In one series of patients with gram-negative septicemia and urinary obstruction complicated by infection, PCN reduced mortality from 40% to 8%.²² However, PCN in patients with pyonephrosis may exacerbate or precipitate septicemia as a result of bacteria entering the bloodstream through peripapillary veins from catheter manipulation or overdistention.²²^,²³

In patients with fungal urinary infections, antifungal agents can be infused directly into the collecting system. This approach is advantageous because effective therapeutic levels can be achieved in the urinary tract without the associated systemic toxicity from IV administration. Fungus balls can be disrupted mechanically and extracted through the nephrostomy tract.⁸^,²⁴

In most patients with azotemia due to obstruction, PCN provides rapid improvement of renal function.²⁵ The procedure commonly is used as a temporizing measure to improve renal function while the underlying obstruction is addressed definitively. In patients with terminal malignancies and azotemia due to bilateral obstruction, unilateral PCN usually suffices to preserve renal function.²⁶ Bilateral drainage is indicated if pyonephrosis is suspected or unilateral drainage is unsatisfactory for restoring renal function. Unfortunately, the median survival rate of patients with advanced malignant urinary obstruction is 3 to 7 months.²⁷ Even with careful patient selection, 32% of patients are unable to achieve any improvement in quality of life after PCN.²⁸ After an open and frank discussion about the physical, emotional, and financial burdens associated with a drainage catheter, most patients and families opt for the drainage catheter as a means to extend life for as little as a few months.

Complications

The mortality rate for PCN is about 0.2%, which compares favorably with the mortality rate for surgical nephrostomy (≤6%).²⁰ The major procedure-related complications are bleeding and sepsis. Hemorrhage requiring transfusion or other treatment occurs in 1% to 3% of patients undergoing PCN.²⁰ One series of 144 nephrostomies placed using combined CT and fluoroscopic guidance had no hemorrhagic or other major complications.²⁹ Most bleeding associated with PCN is transient and self-limited. It is not uncommon to have pink urine for several days after the procedure. If small clots block the catheter, the catheter should be irrigated with sterile saline.

Major arterial injury should be suspected when the urine remains grossly bloody after 3 to 5 days, when new clots are demonstrated in the collecting system on follow-up nephrostograms, or when there is a significant drop in hematocrit. These patients should undergo angiographic evaluation with embolization of injured vessels (Fig. 23-11). If the initial angiogram is negative, the nephrostomy may be removed over a guidewire to relieve the tamponading effect of the catheter, and the angiogram is repeated. If the drop in hematocrit is out of proportion to the quantity of blood in the urine, the patient may have a retroperitoneal hematoma. Retroperitoneal hemorrhage is best evaluated with CT. Unsuspected retroperitoneal hematomas not requiring treatment have been reported in up to 13% of patients.³⁰ Significant hemorrhage usually is caused by laceration of lobar arteries. Pseudoaneurysm, arteriovenous fistula, arteriocaliceal fistula, or frank extravasation may be seen at arteriography. The risk of hemorrhage is minimized by using fine needles for puncture, using appropriate guidance, and avoiding puncture of the anteromedial renal vessels. The vast majority of these complications can be managed endovascularly.³¹

Figure 23-11 Arterial injury from percutaneous nephrostomy. The patient had persistent bright red hematuria after removal of a lower pole nephrostomy. A, Selective left renal artery angiography shows active extravasation (arrow) from a lower pole branch in the previous location of the nephrostomy tube. B, A 3-Fr microcatheter (arrowhead) has been advanced to the distal aspect of the offending branch and injection shows extravasation (arrow).C, Angiography from the microcatheter (arrowhead) after coil embolization (arrow) shows reflux into normal renal artery branches and occlusion of the previously bleeding lower pole branch.

Although there is always concern for infection in patients with the need for urinary decompression, sepsis only occurs in approximately 1% to 3.6% of patients undergoing nephrostomy placement (the higher incidence seen in patients undergoing decompression for suspected infection).³² Patients with infected urine or stones are at higher risk for PCN-related sepsis. For elective PCN for stone disease, antibiotic therapy ideally should be initiated and continued until the urine is clear. Diagnostic nephrostograms, ureteral catheterization, and stent placement should be delayed in patients with pyonephrosis until the urine has cleared.

Pleural complications include pneumothorax and empyema from infected urine entering the pleural space along the nephrostomy track. These complications are prevented by obtaining access beneath the 12th rib. One study showed that PCN tracks above the 12th rib traverse the pleura in 29% of cases on the right and 14% of cases on the left.³³ Pleural complications occur in only about 0.2% of decompressive nephrostomies.²¹ When supracostal access is required for stone therapy, the risk of pleural complications increases to as much as 12%.³⁴^,³⁵ However, many pleural transgressions remain clinically silent.

Minor perforations of the collecting system occur in about 2% of patients. If a satisfactory drainage catheter is placed in the collecting system, these leaks usually heal spontaneously over the next 48 to 72 hours. The risk of urine leak as well as hemorrhage is increased with a direct renal pelvis puncture (Fig. 23-12). Urinomas requiring drainage are less common and occur rarely with standard 8- to 12-Fr PCN tubes. After removal of larger PCN catheters used for nephrostolithotomy, urinomas are more common. Other rare complications of PCN include air embolism and puncture of the colon, spleen, liver, and gallbladder.³⁶^–³⁹

Figure 23-12 A, Nephroureteral catheter (arrow) was placed to treat a ureteral stricture. Injection of the catheter shows extravasation (arrowheads) extending from the pelvis and along the track. B, Computed tomography shows that the catheter (arrowheads) directly enters the renal pelvis. Extravasated contrast (arrow) is present in the perinephric space along the track.

Catheter dislodgment is a relatively common occurrence. In a recent review of 283 patients with 325 nephrostomy tubes, there was an episode of complete dislodgment of the catheter in 16.6% of the patients. The vast majority of the tubes were replaced through the preexisting track, with a limiting factor of track maturity. Successful replacement rates were 17%, 35%, and 97% in tracks less than 4 weeks old, less than 6 weeks old, and more than 6 weeks old, respectively.⁴⁰ Some patients have recurrent dislodgment of their tubes. One author describes a solution by placement of a renal “U-tube.” This tube goes in one polar calyx and out the other pole with side holes within the collecting system.⁴¹ Malecot catheters commonly used after nephrostomy track dilation may become difficult to extract if tissue bridges grow over the catheter flanges.⁴² These devices should therefore be used with caution for long-term drainage. The entrapped catheters may be safely removed using endoscopic techniques to cut the anchoring tissue bridges.

Ureteral stent placement

Patient selection

Ureteral stent placement is indicated for a broad variety of clinical problems (Box 23-2). PCN tube placement with antegrade stent placement usually is reserved for patients in whom retrograde attempts are unsuccessful or not feasible. For patients with nephroureteral obstruction, ureteral stents have distinct advantages over external drainage through a PCN tube. The drainage with stents is internalized, eliminating the need for external drainage tubing and collecting bags. The completely internalized ureteral stent is tolerated better by patients, and it decreases the risk of urosepsis from the inevitable colonization of external drainage catheters.⁴³^,⁴⁴ Ureteral stents also have several disadvantages. Stent malfunction may not be detected quickly and often requires sonography or cystography for diagnosis. Stent patency varies with the clinical situation. Stone-forming patients tend to develop rapid stent occlusion, and stent exchange may be required as frequently as every 6 weeks. In general, stents should be exchanged at least every 6 months with transurethral cystoscopic or fluoroscopic guidance to prevent encrustation and occlusion. Stents may cause debilitating irritation of the bladder wall or trigone. Some patients prefer externally draining PCN tubes because function can be assessed easily and replacement is simple.

The nephroureteral (NU) stent is an alternative to externally draining PCN tubes and internally draining ureteral stents. This device differs from the standard double-J ureteral stent in that it has a retention loop positioned in the renal pelvis and a short segment of catheter extending out the nephrostomy track. The external segment of catheter may be capped to restore antegrade flow of urine from the renal pelvis, through the stent, and into the urinary bladder. The advantage of this device is that diagnosis of occlusion requires only a nephrostogram. If the patient develops flank pain or fever, she or he can open the catheter to external drainage until receiving medical attention. Likewise, catheter exchange over a guidewire is simple and does not require anesthesia, cystoscopy, or other transurethral interventions. These catheters are ideal for short-term ureteral stenting when it is advantageous to maintain access to the upper urinary tract for further evaluation with nephrostograms or a Whitaker test.

External PCN drainage is preferred over ureteral stents in several situations, particularly when there are contraindications to ureteral stent placement (Box 23-3). In the occasional patient with vesicocutaneous fistula due to advanced pelvic malignancy, diversion of urine with ureteral occlusion is beneficial to facilitate fistula closure and minimize tissue breakdown and nursing care requirements. Nephroureteral catheters are available with ureteral occlusion balloons to treat this difficult group of patients.

Technique

For antegrade stent placement, the ideal nephrostomy access should provide a reasonably straight vector down the ureter from an interpolar or upper pole calyx. However, with available guidewires, catheters, and sheaths, antegrade stents can be placed even from a lower pole access. Stent placement is facilitated by allowing the PCN track to mature for 1 to 2 weeks. Waiting allows access-related bleeding and hematuria to clear, decreasing the risk of stent occlusion from blood clots. Decompression via percutaneous drainage also reduces urothelial inflammation and edema. Once the system has been decompressed for several weeks, it is generally easier to negotiate the ureteral obstruction with a wire, catheter, and subsequently a stent.

Almost all ureteral strictures can be traversed with a curved catheter and an angled hydrophilic guidewire (Fig. 23-13). If the catheter buckles in the renal pelvis, a sheath may be advanced into the proximal ureter. When the guidewire has crossed the obstruction, a catheter should be advanced and injected to confirm its location in the bladder. Vigorous or overzealous manipulation of the hydrophilic guidewire may easily puncture the urothelium. A 4-5 Fr hydrophilic catheter usually follows the hydrophilic guidewire into the urinary bladder. The hydrophilic guidewire should then be exchanged for a stiff guidewire. If necessary, the stricture is dilated to allow the ureteral stent to pass freely to the bladder. Dilators may be used to dilate to 1 Fr size larger than the ureteral stent. Alternatively, a 3- to 4-mm angioplasty balloon may be used.

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