Indications for Retrograde Ureteral Stents

Retrograde ureteral stents are placed for diverse types of ureteral obstruction, or prophylactically to prevent obstruction after manipulation of the genitourinary (GU) tract. Stents are used to temporize blockage with refractory symptoms, signs of infection, or renal functional compromise, until definitive treatment can be provided. Patients with obstruction and infection should always be decompressed to relieve obstruction prior to UUT manipulation to avoid precipitating urosepsis.

Ureteral stents are commonly used for intrinsic causes of blockage, such as stone disease, ureteral strictures, ureteral tumors, or papillary necrosis. However, stents may also be used for extrinsic processes, for example, retroperitoneal fibrosis (RPF) or regional malignancy. Progressive local processes (for example, malignancy) may render internal drainage less effective over time; however, ureteral stents may still be a useful short-term strategy. Many patients will benefit from chronic internal urinary drainage, especially with relatively stable chronic obstruction due to malignancy or scar tissue, with contraindications to more definitive management (e.g., UUT reconstruction).

DJS, also known as double pigtail stents, are often placed at the conclusion of a ureteroscopic procedure for stones, biopsy, or other manipulations to prevent obstruction from ureteral edema or bleeding. DJS may be used to passively dilate the ureter following ureteroscopy or shock wave lithotripsy, to facilitate passage of stone fragments after stent removal. In the setting of concern for iatrogenic ureteral injury during ureteroscopy, a stent may be left for a longer period of time (e.g., 4–6 weeks) to enable further healing around a buttressed ureter. DJS are placed after UUT reconstruction such as pyeloplasty, reimplant, or ureteroureterostomy to reduce the likelihood of obstruction from ureteral edema and to promote antegrade flow to prevent leakage. Duration of stent placement after these procedures varies depending on provider and local practice patterns. Occasionally stents are placed for flank pain in the setting of equivocal obstruction to determine if pain improves with internal drainage.

“Single J” stents are used during urinary diversion surgery to ensure drainage from the UUT following ureteral implantation, for instance, into an ileal conduit. These are temporary, until they fall out or are removed after a certain interval after surgery.

Finally, ureteral stents may be placed perioperatively for patients undergoing colorectal, gynecologic, or retroperitoneal surgery to enable identification of the ureters intraoperatively with the goal of avoiding iatrogenic injury. These temporary stents are generally 5Fr “open ended” or Pollack catheters that are secured to the Foley catheter and removed at the conclusion of the case or when the Foley is removed.

In patients with bleeding diathesis or active anticoagulation requiring urgent decompression, internal drainage is preferred to external drainage to mitigate the risk of bleeding from percutaneous tube placement.

Indications for Nephrostomy Tubes

Percutaneous nephrostomy (PCN) tubes are placed for more selective indications than are DJS, as retrograde drainage is often preferred due to the lack of an external tube and drainage bag. Obstruction is the primary indication for PCN, comprising 85–90% of indications. Indications for PCN include failed internal stenting (inability to place retrograde stent or obstruction despite stenting), obstructive urosepsis (to reduce manipulation of the GU system and possible worsening of clinical infection), patient’s preference (e.g., severe stent-related morbidity such as flank pain or irritative symptoms), or for bulky or progressive local malignant processes in which DJS are considered likely to fail.

PCNs may be placed in anticipation of percutaneous nephrolithotomy (PCNL) with strategic placement in a certain calyx to enable direct and/or safe access to the stones of interest, or to enable a percutaneous intervention for an UUT tumor (e.g., antegrade resection or ureteroscopy). Uncommonly, PCNs are used for administration of UUT chemotherapy (e.g., mitomycin or Bacillus Calmette-Guerin [BCG]) for treatment of recurrent or high-grade, noninvasive urothelial cancer.

PCNs may be placed for diagnostic purposes as well. A PCN affords the option of an antegrade contrast study of the UUT that can delineate renal and/or ureteral anatomy for surgical planning (e.g., for stricture disease) or to assess healing of a reconstructed system. PCN can be used for a Whitaker test to assess for UUT obstruction with an equivocal nuclear renal scan. Finally, PCNs may be placed for flank pain and equivocal obstruction to determine if there is relief of symptoms with external drainage.

Indications for Antegrade Ureteral Stents

Ureteral stents may be placed in antegrade fashion when retrograde stenting is not feasible (e.g., from an impacted stone or with anatomic distortion within an ileal conduit). Patients require percutaneous access for this procedure. Antegrade stenting may enable stent placement in the setting of malignant extrinsic obstruction when retrograde stenting may not be feasible. Chitale et al. reported only a 21% success rate of retrograde stenting, compared to 96% for a two-staged antegrade approach for obstruction due to malignant pelvic disease, with other studies reporting a success rate for antegrade stent placement of up to 88%.

It is important to underscore that comparative data for DJS versus PCN for different obstructive indications are generally retrospective and prone to selection bias. Given the absent level 1 evidence, the use of internal verus external drainage for UUT obstruction is often individualized to the patient, with the exception of clear indications for one type of procedure (e.g., PCN for active urosepsis with obstruction).

Stent Symptoms

The most common issue related to indwelling DJS is stent morbidity. These symptoms may include flank pain, abdominal pain, irritative voiding symptoms, bladder spasms, and gross hematuria. Stent symptoms can range from mild to debilitating. In one study of 120 patients with indwelling ureteral stents, 80% of patients experienced bothersome symptoms and 40% reduced work capacity. The most commonly experienced symptoms were pain (80%), and frequency, urgency, or dysuria (60%). Additionally, 40% of patients also reported sexual dysfunction. The authors reported that stent-related symptoms led 40% of patients to seek the assistance of family members in their routine daily activities and 20% to seek medical assistance.

Stent position can exacerbate related symptoms. In particular, incomplete distal curls, distal curls crossing the midline of the bladder, or proximal curls located in a calyx are associated with a higher degree of stent symptomatology.

Management of stent morbidity includes ruling out a more significant process, such as urinary tract infection or stent malposition with obstruction. Urine culture, with or without empiric antibiotic treatment, and imaging, such as abdominal x-ray (KUB), can be considered to evaluate these issues. Diverse oral medications can be used to treat stent pain or irritative symptoms such as analgesics, anticholinergics, phenazopyridine, and alpha-1 adrenoreceptor blockers. Tamsulosin has been shown to reduce stent-related symptoms in prospective comparative studies. A recent randomized study showed that tamsulosin plus tolterodine had no increased reduction of stent morbidity versus tamsulosin alone. Intravesical agent instillations (ketorolac and oxybutynin) have been studied and shown to decrease pain compared to placebo; however this treatment remains uncommon. Other more invasive treatments for stent pain have been studied, including ropivacaine injection around the ureteral orifice, which was shown to potentially decrease pain and voiding symptoms in one study. In another study, botulinum toxin A was injected around the ureteral orifice and was shown to improve postoperative pain and decreased narcotic requirements.

If ureteral stent symptoms are not able to be controlled, hospitalization with intravenous pain control, early removal, or placement of percutaneous nephrostomy tubes can be considered. Finally, given high rates of stent morbidity, thought should be given to the indication for stenting in the first place, and duration of stenting, to reduce patient suffering. While there are data suggesting that stenting after uncomplicated ureteroscopy is not necessary, and American Urological Association (AUA) guidelines consider stenting optional after these procedures, provided certain criteria are met (e.g., absence of ureteral injury, normal anatomy, normal renal function), it is common for stents to be placed routinely in patients to avoid the risk of postoperative obstruction. A reasonable approach to stenting is to use a tether to enable easier removal (obviating the need for office cystoscopy) within several days of a procedure; however, this may generate fear of inadvertent dislodgment. Ultimately additional research is needed to improve stent design and pharmacologically reduce morbidity to improve the patient experience related to these procedures.

Urinary Tract Infection/Sepsis

If ureteral stents are placed in the setting of known urinary infection or sepsis, appropriate antibiotic coverage with culture-specific or broad-spectrum antibiotics is the standard of care. If stent placement is performed without clinical suspicion for infection, a culture should be sent preoperatively if possible; otherwise the American Urological Association Best Practice Statement for antibiotic prophylaxis recommends fluoroquinolone or trimethoprim-sulfamethoxazole (TMP-SMX) as first-line and first-/second-generation cephalosporins, aminoglycoside with or without ampicillin or amoxicillin/clavulanate as second-line prophylactic agents, with consideration of local resistance patterns. Obstruction and infection can readily lead to urosepsis, and while decompression is essential to mitigate risks, instrumentation itself can precipitate bacteremia and hemodynamic instability. Indeed, Flukes et al. reported that 12% of patients with obstructed infected kidney required ICU admission before intervention, and another 6% deteriorated after retrograde intervention, necessitating hemodynamic support in the ICU.

Risk factors for UTI associated with ureteral stents that are in place more chronically include longer duration of stent retention, presence of certain comorbid systemic diseases (diabetes mellitus, chronic renal failure, and diabetic nephropathy), and female gender. Stents removed within 30 days of insertion have a lower risk of UTI compared with those removed after 90 days (6.8% vs 28.6%, respectively). Interestingly, the stent colonization rate was much higher in longer duration stents (64.9% vs 20.5%, respectively).

Periureteral Fluid Collection (Sterile or Infected)

During ureteral stent placement, extravasation of fluid can occur by two mechanisms – either by direct instrument damage (perforation) or indirectly by increased fluid pressure (rupture) ( Fig. 21.1 ). Patients may experience flank pain, fever, and/or ileus, or they can be asymptomatic. These events are generally apparent via retrograde pyelography at the time of intervention; however, if there is postoperative concern, cross-sectional imaging will show a fluid collection, which can contain urine, blood, contrast, or irrigation fluid. In rare cases, stone fragments can migrate into this collection, which may be insignificant or may create an abscess in the setting of infection.

Contrast extravasation during retrograde ureteral stent placement.

Treatment for periureteral collections typically involves a longer duration of ureteral stenting to encourage antegrade urine flow and buttress the injured ureter. If a patient has worsening symptoms or is clinically infected, a percutaneous drain may be required. Intravenous antibiotics and inpatient observation may be required depending on the clinical scenario. If there is persistent urinary drainage into a periureteral collection, proximal diversion of the urine via nephrostomy tube drainage is indicated. Unless there is a foreign body or abnormal tissue such as in prior radiation therapy, a ureteral perforation should heal within 2–4 weeks of ureteral stenting.

Wire-Related Complications

There are many different types of wires available for retrograde stent placement (e.g., hydrophilic, hybrid wires, stiff wires). It is preferable to use a wire with a flexible tip to minimize intrarenal injury and risk of bleeding/perforation, especially in the setting of anticoagulated patients. It is also important to ensure that the wire is placed intraluminally rather than submucosally. If significant resistance is encountered during wire placement, the wire should be removed and replaced. Placing a 5Fr catheter over the wire can help confirm that the wire is in the correct position based on lack of resistance and ability to perform a retrograde contrast injection. Placing a wire past an impacted stone may increase the risk of submucosal placement or perforation, and judicious use of a flexible tip catheter, including an angled tip when necessary, monitoring with fluoroscopy, and knowing when to halt attempts at retrograde access can help to reduce these risks.

There is one report of significant intraperitoneal bleeding after stent placement. A patient developed hemorrhagic shock after uneventful stenting, which led to exploratory laparotomy with splenectomy to find and control the source of bleeding, which was intraoperatively identified as a 6-mm renal upper pole puncture. The article emphasized the importance of ensuring the wire is placed correctly with the flexible tip first to avoid trauma from a rigid wire.

If there is significant urinary tract bleeding from mucosal injury/wire trauma, we recommend placing the retrograde stent and monitoring the patient closely. Any bleeding diathesis should be reversed if possible. Continuous bladder irrigation may be needed depending on degree of hematuria.

Stent Migration

Ureteral stents can migrate proximally into the kidney or distally into the bladder ( Fig. 21.2 ). Rates of stent migration reported in literature range from 8% to 9%. The etiology is thought to be an incorrectly sized stent (if migration occurs in a delayed fashion) or technical error (during surgery, when the distal end of the stent is pushed too far and becomes intraureteral).

DJS with proximal curl in proximal ureter.

Management includes stent removal and reinsertion for distal migration, and ureteroscopic removal and reinsertion for proximal migration. The latter can be challenging depending on the caliber of the ureter. Several types of graspers and baskets can be used to retrieve the distal end of the stent and to reposition the stent. If this cannot be safely accomplished, “tandem” stenting can be performed to enable ureteral dilation to allow retrieval of the migrated stent at a later point (1–2 weeks).

Adjacent Organ Injury/Stent Erosion

A rare complication of ureteral stents is erosion into adjacent vascular structures or organs and development of fistulas. Arterio-ureteral fistulas are rare but life threatening. Risk factors include previous cancer surgery/radiotherapy (54%), vascular surgery (31%), and known aneurysm or pseudoaneurysm of the iliac artery (38%). Often, patients present only with massive hematuria. If hemodynamic compromise ensues, mortality rates are reported to be up to 23%, with delayed diagnosis being associated with worsened outcomes. Diagnosis can be confirmed with angiography, and management includes a combined approach comprising urology, vascular surgery, and interventional radiology. The preferred approach is stenting of the involved artery; however, options also include ligation, repair, or embolization of the involved vascular structure. The ureter is generally treated conservatively with stenting and/or nephrostomy drainage, and delayed reconstruction may be needed.

Ureteral stents can also erode into the venous system. These events have included erosion and migration via renal, iliac, or ovarian veins into the vena cava and even the right ventricle. One patient with a ureteral stent in her right heart had only mild back pain and suprapubic discomfort after voiding. When the stent migrates to the right ventricle, open heart surgery may be necessary to remove it. When stents are placed into or erode into veins, initially there can be hematuria, or there may be no initial symptoms with large bleeding encountered upon stent removal.

There are reports of stent erosion into adjacent organs, such as the colon or vagina, leading to fistulization. These are very rare events and require stent removal and possible reconstructive surgery. Erosion into the uterus has been reported with antegrade stenting.

Stent Encrustation

Underlying metabolic conditions, urinary supersaturations, pregnancy, and increased indwelling stent times increase the likelihood of stent encrustation. One study showed encrustation rates of 9.2% at <6 weeks and up to 76.3% at >12 weeks. Another study reported encrustation rates of 26.8% at less than 6 weeks, 56.9% at 6 to 12 weeks, and 75.9% at more than 12 weeks. Encrustation can occur on the distal intravesical portion of the stent, along the intraureteral portion, or on the proximal curl within the renal pelvis. Vigilance regarding the timing of stenting is needed when treating patients who are particularly lithogenic or pregnant, and exchange should occur up to every 4–6 weeks depending on the clinical circumstance.

Diagnosis can be made at the time of cystoscopy, when encrustation is visualized and stent cannot be extracted with the aid of a grasper in the standard transurethral fashion. The diagnosis can also be made using noncontrast CT. Plain x-rays are not recommended, because they may miss minor (but removal-complicating) encrustations.

Attempting to cystoscopically remove an encrusted stent with excessive force can lead to fracturing of the stent or avulsing or intussuscepting the ureter. The management strategies for an encrusted stent therefore include extracorporeal shock wave lithotripsy, cystolithalopaxy, manual scraping of the encrustations from the stent by extraction through a ureteral access sheath, ureteroscopy with intracorporeal lithotripsy, percutaneous nephrolithotomy, and open or laparoscopic pyelolithotomy and/or cystolithotomy. The exact approach depends on burden and the location of encrustation. Often, patients will need more than one procedure.

There may be instances in which a stent cannot be removed due to low volume encrustation, and ureteroscopy adjacent to the stent cannot be performed due to narrow anatomy. A second or “tandem” stent can be considered adjacent to the indwelling stent, with staging of the procedure to enable further ureteral dilation and retrograde fragmentation of encrustation in the future.

If a significant ureteral injury occurs during attempted stent removal, such as avulsion or intussusception, a percutaneous nephrostomy tube is generally required with consideration of acute or delayed ureteral reconstruction.

Stent Fragmentation

While stents are designed of sturdy material, there is a risk of stent fragmentation. This may occur from overzealous use of the laser contiguous with the stent or spontaneously. For the former, care in lasing adjacent to an indwelling stent can obviate this issue. The latter is a rare event, but there are published series of spontaneous fragmentation. Plain x-ray, as well as computerized tomography, can diagnose stent fragmentation. It can also be diagnosed at the time of surgery, when an incomplete stent is extracted from the ureter. Management strategies include removal of fragments endoscopically, either retrograde from the bladder or ureter, or percutaneously if needed.

Retained Stent

Retained stents can present a significant clinical problem. These stents are at risk for encrustation and can be challenging to remove (see section on encrusted stents for more detail). Retained stents that become encrusted may increase the risk of ureteral injury and can lead to renal atrophy. All patients undergoing stent placement should be counseled that stents are temporary and require exchange or removal to avoid complications. This information should also be provided in paper form for counseling and medicolegal reasons. Stent registries have been used to track patients to reduce the likelihood of retained stents. There are various formats of stent registries in use, ranging from manual handwritten “card” systems, computer based with automatic reminders to providers, to even automatic letter and cellular phone texting reminders to patients.

Inadequate Relief of Obstruction/Hydronephrosis

Ureteral stents may not adequately relieve obstruction, whether the primary process is benign or malignant. Stent failure rates of up to 6% have been reported for urolithiasis. Stent failure rates are greater, however, with malignant extrinsic obstruction, with obstruction rates as high as 44% within 30 days and 58% with longer follow-up. Stent failure can be diagnosed by increased hydronephrosis, worsened kidney function despite absent other causes, or clinical suspicion. Management may include stent exchange and monitoring, placement of tandem stents, placement of a metallic stent that can be more resistant to extrinsic compression, or more proximal diversion (percutaneous nephrostomy tube placement). Benign extrinsic compression (e.g., retroperitoneal fibrosis) can also lead to stent failure.

Metal Stents

When conventional ureteral stents fail, metal stents have been used for long-term drainage in an effort to avoid percutaneous nephrostomy tubes and improve the patient’s quality of life. Compared to polymeric ureteral stents, metal stents preserve patency under a greater degree of extrinsic compression and have longer indwelling times necessitating fewer stent changes (up to 12 months). However, they are associated with a high rate of migration (up to 81%), stone encrustation (23%), and obstruction resulting from hyperplastic reaction (up to 60%). Tumor ingrowth has also been reported. Metal stents are used mostly for malignant obstruction. One small study reported 100% patency rate (mean follow-up 8.5 months) in patients with malignant obstruction, but only 44% with benign obstruction. A study with longer follow-up (median 15 months) reported 62% patency rate for malignant obstruction. Retrospective studies have shown that metallic stents may not perform better than regular stents in preventing obstruction, particularly in patients with locally invasive prostate cancer; however, there are insufficient data to draw a definitive conclusion. The higher cost of metallic stents raises the question of cost-effectiveness, which requires additional investigation.