INTRODUCTION — Ureteral stents are one of the most common devices used by urologists. They are placed with cystoscopic guidance in an operating room setting. Ureteral stents are used to relieve ureteral obstruction, promote ureteral healing following surgery, and assist with ureteral identification during pelvic surgery. Ureteral stent placement is associated with some degree of morbidity in the majority of patients that ranges from generalized urinary discomfort to urinary tract infection or obstruction. Much of the morbidity is related to the biocompatibility of the materials used to fashion the stent and, to some extent, their design; unfortunately, the ideal stent has yet to be discovered.
This topic will discuss the indications for ureteral stenting, technique of ureteral stent placement, management of stents, and stent complications. The management of urinary obstruction and urinary tract infection are discussed in detail elsewhere. (See "Clinical manifestations and diagnosis of urinary tract obstruction (UTO) and hydronephrosis" and "Sampling and evaluation of voided urine in the diagnosis of urinary tract infection in adults".)
INDICATIONS FOR STENT PLACEMENT — Ureteral stents are functionally used to reestablish or maintain the patency of the ureter. Ureteral stents passively dilate the ureter; urine flows through the center of the hollow stent as well as around the stent, facilitating the passage of debris [1,2]. Stent insertion initially increases ureteral peristaltic activity, but with time, the frequency and amplitude of ureteral peristalsis decreases [3-5]. Indications for ureteral stent placement include the following:
Ureteral obstruction — Ureteral obstruction due to nephrolithiasis, tumor, or retroperitoneal fibrosis can be uncomplicated, or complicated by urinary tract infection, renal insufficiency, or renal failure . Patients with complicated obstruction need prompt decompression of the urinary tract with either placement of an indwelling ureteral stent or a percutaneous nephrostomy tube [7-9]. Retrograde ureteral stent placement and percutaneous nephrostomy both effectively relieve obstruction and infection due to ureteral calculi. In two randomized trials comparing both treatment modalities, neither modality demonstrated superiority in promoting a more rapid recovery after drainage [10,11]. The management of urinary tract obstruction is discussed in detail elsewhere. (See "Clinical manifestations and diagnosis of urinary tract obstruction (UTO) and hydronephrosis" and "Kidney stones in adults: Surgical management of kidney and ureteral stones".)
A ureteral stent is generally chosen first to help relieve urinary tract obstruction because it is less invasive and has a lower risk of bleeding compared with placement of a percutaneous nephrostomy tube. However, in cases where a stent cannot be placed endoscopically or if the patient will require future percutaneous treatment of their stone burden, a percutaneous nephrostomy tube is placed primarily.
Ureteral anastomosis — Stents are typically placed following the creation of a ureteral anastomosis (ie, ureteroureterostomy) to buttress the repair and ensure continued urine flow in spite of inflammation and swelling. Ureteral repair is performed for ureteral injury (eg, trauma, iatrogenic), kidney surgery (eg, pyeloplasty), or renal transplant (ie, neo-ureterostomy). (See "Urinary tract injury in gynecologic surgery: Identification and management" and "Kidney transplantation in adults: Overview of the surgery of deceased donor kidney transplantation".)
Prophylactic — Prophylactic ureteral stents may be placed prior to extracorporeal shock wave lithotripsy (ESWL) if the patient has large stones (>1.5 cm) to prevent ureteral obstruction [12,13], following complicated ureteroscopy due to concerns for ureteral inflammation and swelling, or prior to surgery to assist with intraoperative identification of the ureter (eg, gynecologic surgery, rectosigmoid surgery, aortoiliac surgery), which is particularly important when the operative field is scarred from previous dissection [14-18]. (See "Kidney stones in adults: Surgical management of kidney and ureteral stones", section on 'Shock wave lithotripsy' and "Radiofrequency ablation, cryoablation, and other ablative techniques for renal cell carcinoma".)
In a large global study of almost 10,000 patients with ureteric or renal stones, the placement of a preoperative ureteral stent increased stone-free rates (with stent 79.6 versus without stent 72.9 percent) and decreased complication rates (with stent 10.6 versus without stent 13.2 percent) in patients with renal stones but not in those with ureteral stones .
Routine prophylactic stenting is not mandatory following uncomplicated ureteroscopy for ureteral stone disease; patients and clinicians may choose individually based on risks and benefits. Stents placed after ureteroscopic lithotripsy are associated with higher incidences of lower urinary tract symptoms . Omitting a stent post-ureteroscopy, on the other hand, has been associated with more postoperative complications  and more unplanned medical visits (odds ratio 1.63, 95% CI 1.15-2.30) due to early obstruction .
Ureteroscopy can also be performed for the treatment of transitional cell carcinoma (TCC) of the ureter or kidney or for evaluation/treatment of a ureteral stricture. However, placement of a stent is fairly standard following both of these procedures.
URETERAL ANATOMY — The ureters are bilateral tubular structures approximately 22 to 30 cm in length that are responsible for transporting urine from the renal pelvis to the bladder. The ureters begin posterior to the renal artery and course medially along the anterior surface of the psoas muscle. The gonadal vessels cross anterior to the ureter proximally, and distally the ureters pass over the common iliac arteries near their bifurcation. The ureter then enters the trigone of the bladder.
The ureter is anatomically divided into upper, middle, and lower segments. The proximal ureter includes the ureter from the renal pelvis to the upper border of the sacrum. The middle ureter is that portion between the upper and lower margins of the sacrum, and the distal ureter extends from the lower border of the sacrum to the bladder. The ureter can also be divided into the abdominal and pelvic ureter, with the abdominal ureter between the renal pelvis and iliac bifurcation and the pelvic ureter below the iliac bifurcation to the bladder .
The ureteral wall is composed of several layers that include (inward to outward) an inner transitional epithelium that is in contact with urine, the lamina propria, an inner longitudinal muscle layer, and an outer circular muscle layer and adventitia. The muscle layers are responsible for peristalsis. The adventitia is composed of loose connective tissue and contains blood vessels and lymphatics that traverse alongside the ureter.
The normal ureter has three areas of narrowing that are clinically important for safe and successful ureteral endoscopy as well as stent placement. The first occurs at the ureteropelvic junction where the renal pelvis tapers into the proximal ureter. The second occurs as the ureter crosses the iliac arteries. The combination of angulation and ureteral compression is likely the cause for narrowing at this site. Lastly, the ureter is narrowed at the ureterovesical junction as it passes obliquely through an intramural tunnel of 1.5 to 2 cm in length before terminating at the ureteral orifice .
Cases of complete or partial duplication of the ureter can complicate ureteral stent insertion. The incidence of ureteral duplication is 1 in 125 individuals . In cases of complete duplication, it is important to understand the Weigert-Meyer rule, which states that the orifice to the lower pole ureter is more cranial and laterally positioned and the upper pole ureter is caudal and medial.
A ureteral stent can generally be placed without manipulation of the ureteral orifice or the ureter. If anatomy is in doubt (eg, stenosis, question of duplication), a retrograde pyelogram should be performed.
STENT DESIGN — Ureteral stents are basically hollow tubes with multiple side holes. The proximal and distal ends are typically curled (ie, double pigtail) to limit stent migration (picture 1). The use of a string attached to the distal coil of a stent can also be used to facilitate stent extraction without requiring a cystoscopy for stent removal .
A myriad of stent designs are available with variations in stent material, coating, size, and shape. The design of stents is aimed at improving patient comfort and stent handling and reducing the incidence of urinary tract infection and encrustation . However, most novel designs have not shown a significant improvement in stent-related symptoms over the standard double pigtail stent . Moreover, while the standard indwelling ureteral stent costs between $80 and $100, most novel stents cost $150 or more, with cost varying depending upon the type of stent and the manufacturer. The benefit to the patient versus the cost of the stent must be considered when a novel stent is used.
Materials — During the course of stent development, various materials have been used [29,30]. Stents were initially composed of polyethylene and polyurethane, but these materials were rigid and associated with significant patient discomfort, urothelial erosion and ulceration, encrustation, and fragmentation.
Proprietary materials that are primarily silicone based are used in contemporary stents . Silicone is inert, flexible, and elastic and therefore one of the most tolerated biomaterials . However, silicone is prone to collapse with compression and is sometimes difficult to push into narrow or tortuous ureters. Silicone also has a low tensile strength and can snap if stretched too much. There is no definitive evidence on the impact of stent material on stent-related symptoms .
Biodegradable stents dissolve over time and would ideally mitigate the need for stent removal; however, incomplete stent dissolution can result in ureteral obstruction or become a nidus for urinary tract infection or encrustation [34-36].
Metal stents can be used to relieve ureteral obstruction when increased radial force is needed to maintain ureteral patency, typically from tumor, which can be intrinsic, causing ureteral stricture, or extrinsic, causing compression . Metal stents are better able to resist external compression compared with standard stents, and they generally require fewer stent changes [38-43]. The use of metal stents for the treatment of benign ureteral strictures is undefined.
Four types of metal stents have been used and include self-expanding, balloon-expandable, and covered stents (eg, Resonance, also known as a coil-based stent) and thermo-expandable stents (eg, Memokath) [42,44,45]. The self-expanding and balloon-expandable stents are short stents that are not meant to be changed or removed and are generally no longer used in the ureter. The covered metal stents (eg, Resonance) and thermo-expandable metal stents (eg, Memokath) span the entire length of the ureter and are currently in use. Thermoexpandable stents are differentiated from self-expanding stents in their ability to change conformation depending upon temperature. In addition to self-expansion, these stents can be uncoiled with the installation of cold saline (<10°C), making stent removal easier.
The main benefit of metal stents in the management of malignant ureteral obstruction is decreased morbidity associated with less frequent stent changes . However, primary patency rates for metal stents are low due to hyperplastic reactions, encrustation, or tumor ingrowth, which can make these stents difficult to remove [47,48]. Patency has improved from past one-year patency rates of 17 to 30 percent to approximately 50 percent [9,37,43,45-48]. In one retrospective review of 119 metal stents placed for malignant obstruction, 45 stents developed a hyperplastic reaction, encrustation, or tumor ingrowth requiring balloon dilation or coaxial stenting to maintain patency . Thirteen of the metal stents migrated and required repositioning. In a later review, stent failure occurred in 9 of 27 patients stented for malignancy over a mean follow-up of 59 months . Larger studies are needed comparing standard ureteral stents with metal stents for managing malignant ureteral obstruction to assess stent-related complications and quality-of-life measures.
A novel technique to manage malignant obstruction places a standard stent parallel to the malfunctioning stent rather than exchanging the stent. In one study, the rate of subsequent malfunction was significantly decreased in the parallel stent group (29 versus 57 percent at one week, 73 versus 100 percent at three months) compared with the stent exchange group . In another study, tandem or twin ureteral stents had a patency rate of 80 percent at three months .
Coatings — Stents are typically coated with materials that are intended to improve function, improve patient tolerance, and minimize the incidence of complications. Hydrogel, a coating composed of a hydrophilic polymer, traps water into its chemical structure, reducing the coefficient of friction of the stent and easing insertion and removal. The coating also decreases encrustation, improving the stent's biocompatibility . Other ureteral stent coatings, such as heparin, silver nitrate, and ofloxacin, can be used to minimize encrustation and biofilm formation [53-55]. However, it is unknown if these coatings reduce clinically significant catheter-associated infections . (See 'Stent encrustation' below.)
Size/shape — The most common ureteral stent design has both a proximal and distal curl (ie, pigtail stent) to minimize stent migration. Other types of stents include multi-length, "non-curled," and tail stents. Tail stents taper to a softer, smaller-diameter distal loop that is designed to decrease bladder irritation [57-59]. (See 'Irritative symptoms' below.)
Stent length depends upon the patient's height. A 24 or 26 cm stent is typically used in the average adult patient. Stent diameter ranges from 4 to 7 French (Fr), though the most commonly used stent diameter is 6 Fr (Fr/3 = diameter in millimeters). A larger-diameter stent (7 or 8 Fr) may be used in cases of malignant ureteral obstruction or following an endopyelotomy. Smaller-diameter stents (4.7 versus 6 or 7 Fr) may reduce irritative symptoms, though results are conflicting [60,61].
Spiral stents have spiral ridges that are designed to promote urine flow around the stent. Experimental studies have shown significantly greater urine flow compared with control stents . In clinical use, these stents can be difficult to deploy and may be more prone to fracture .
Experimental — The ideal ureteral stent would be easy to insert, maintain antegrade flow of urine, maintain its position, minimize stent-related morbidity, and have a low cost. Although the ideal ureteral stent does not exist, efforts to improve these characteristics are ongoing.
Dual-lumen stents improve urine flow in extrinsic ureteral obstruction [63,64]. The design for a dual-lumen stent was based upon the finding that two ureteral stents placed side by side in a ureter with extrinsic compression led to improved urine flow; however, these stents remain experimental .
Dual durometer stents are constructed of two different materials with a more rigid proximal section to prevent migration and a softer distal end to minimize bladder irritation . A number of dual durometer stents are available for clinical use. One trial that randomly assigned 98 patients to a conventional stent or a dual durometer stent (Polaris) did not find any significant differences in patient-reported pain or urinary stent symptom questionnaire scores .
A number of different pharmacological agents have also been incorporated into stent coatings to prevent encrustation, inflammation, and infection [66,67]. In an experimental rabbit urinary tract infection model, significantly decreased bacterial counts and increased survival were seen in animals that had triclosan-loaded stents (bacteriocidal) compared with control stents . It is speculated that the use of drug-eluting stents may result in a lower incidence of stent-related complications.
Strings for stent extraction — Although stent extraction strings are incorporated into the design of most stents (picture 2), there is wide variability in their use for postoperative stent removal. Ureteral stent extraction strings may offer several advantages without increasing stent-related urinary symptoms, complications, or postoperative morbidity; however, the string may lead to inadvertent stent removal [26,68,69].
The urologist decides whether to leave the string attached to the stent or to cut the string off based upon how long the stent is anticipated to remain in place (figure 1). Stent strings can be left in place for patients who will not need the stent for a prolonged period of time (ie, generally less than one week) [26,68,69]. For patients who require an indwelling stent for a longer period of time, the string is removed to avoid inadvertent stent removal. We would generally not use a stent with an extraction string in a patient with malignant obstruction who needs their stent changed every three months. A stent with an extraction string may be used for those who do not tolerate cystoscopy well or for patients known to tolerate the stent poorly and who may wish to remove the stent sooner than the prescribed time. However, the patient may require placement of a new stent in the operating room if obstructive symptoms develop (eg, ureteral inflammation, stone fragments).
In one trial, 68 adults undergoing ureteroscopy for urolithiasis were randomly assigned to receive ureteral stents with or without an extraction string . There were no significant differences between the groups for stent-related quality of life as measured by the Ureteric Stent Symptom Questionnaire (USSQ) on postoperative days 1 and 6, or six weeks following stent removal. Pain with stent removal, and rates of stent complications, including stent migration or infection, were also similar between the groups. Although five stents with extraction strings were inadvertently removed early by the patient, none required replacement.
When the string is left in place, it is generally taped (eg, benzoin and steri-strips, Tegaderm) to the suprapubic region in females or to the dorsum of the penile shaft in males. (See 'Stent removal' below.)
STENT PLACEMENT — Ureteral stents are generally placed by a urologist in the operating room (outpatient setting) since fluoroscopy is needed to verify accurate stent placement.
Preparation — Aspirin, antiplatelet, or anticoagulation therapy does not need to be withheld prior to stent placement. A urinalysis should be obtained prior to stent placement or removal since manipulation of the stent in the setting of a urinary tract infection can lead to bacteremia and sepsis. For patients with a positive urinalysis, urinary instrumentation should be delayed, if possible, until appropriate antibiotic treatment has sterilized the urine.
Antibiotics — Antimicrobial prophylaxis is recommended for all procedures involving cystourethroscopy with manipulation, including ureteral stent placement, to minimize the potential for infection . Evidence supporting antibiotic prophylaxis prior to ureteral stenting is indirect; one trial specifically addresses ureteral stenting .
We prefer the following approach (table 1):
●Patients undergoing elective placement of ureteral stents should have, whenever possible, a urinalysis and urine culture, particularly if clinical symptoms suggest the presence of an active genitourinary infection. If the results are positive, the procedure should be delayed until appropriate treatment has been given, provided such a delay is feasible and appropriate.
●The antibiotic chosen should take into consideration local susceptibility patterns and any recent prior antimicrobial treatment; an alternative agent may be required.
●Antibiotic therapy is discontinued within 24 hours unless there is a preexisting symptomatic urinary tract infection at the time of stent placement, in which case a therapeutic course of antibiotic therapy is given.
Patient counseling — Placement of a ureteral stent is a relatively safe procedure with few complications. Prior to cystoscopy and ureteral stent placement, the patient should be counseled regarding the indication for stent placement, the nature of the procedure, and possible stent-related symptoms and complications. (See 'Irritative symptoms' below and 'Complications' below.)
Stenting technique — Most ureteral stents are placed and deployed in a similar manner. Simple stent placement can be performed without the need for anesthesia. Where fluoroscopy is available, ureteral stents can be placed in an office setting [72-74]. However, any procedure that will require ureteral manipulation or ureteral dilation is generally performed in an outpatient (or inpatient) surgical setting.
Once the patient has been properly positioned (low dorsal lithotomy), prepared, and draped, cystourethroscopy is performed. Lidocaine jelly is administered via the urethra to reduce the discomfort of introducing the cystoscope. Once the cystoscope is in the bladder, the ureteral orifice to be cannulated is identified and a guidewire is placed up the ureter into the renal pelvis under fluoroscopic guidance (picture 3). A 5 Fr access catheter is placed over the wire to the renal pelvis, the wire is removed, and a nephrostogram is performed. The guidewire is replaced and the catheter removed. The ureteral stent is then placed over the wire and pushed into the ureter with a stent pusher. Markings on the stent identify the length of the stent that has passed up the ureter. Fluoroscopy can also be used to monitor stent placement. Once the proximal curl of the stent is noted to be in the renal pelvis (based upon the markings on the stent and fluoroscopy), and the end of the stent is visualized at the bladder neck, the guidewire is removed, deploying the stent.
Correct positioning is confirmed when a full curl is visualized on fluoroscopy in the renal pelvis and in the bladder by endoscopic visualization (ie, double pigtail stent). In patients who are pregnant, ultrasound can be used to verify the position of the proximal curl, thereby avoiding radiation exposure. (See 'Ureteral stents during pregnancy' below.)
Unlike polymer stents, metal stents do not have a lumen to permit placement via the Seldinger technique. Metallic stents are placed through a sheath. During retrograde placement of a metal stent, a guidewire is passed into the ureteral orifice and up into the renal pelvis. A coaxial inner catheter and outer sheath are placed over the wire. The inner catheter is removed, and the metallic stent is placed into and through the outer sheath using the inner catheter as a pusher. The authors use cystoscopy with fluoroscopy during metal stent placement to determine when an adequate proximal curl is present in the renal pelvis and to directly identify the distal curl of the stent .
Stent removal — Stents with extraction strings (figure 1) can be removed by the patient at home or by the urologist in the office by gently and continuously pulling on the string parallel to the urethra until the entire stent is completely removed. Patients can be asked to remove their own stents; however, most patients are not comfortable with the process, and thus, the stent is generally removed by the urologist in the office setting. (See 'Strings for stent extraction' above.)
Stents without extraction strings can also be removed in the office setting. Unlike stent placement, fluoroscopy is not needed for stent removal. After appropriate positioning, preparation, and draping, flexible cystourethroscopy is performed, and the lower pigtail of the stent is identified and grasped. The stent is pulled out as the cystoscope is removed. The presence of encrustation on the proximal or distal coils can complicate stent removal. (See 'Stent encrustation' below and 'Stent exchange/removal' below.)
Symptoms (eg, pain, hematuria, frequency) following stent removal are fairly common (2/3 of patients in one study ). Patients with a ureteral stent in place for >7 days were less likely to experience increased pain immediately following stent removal than patients with a stent in place ≤7 days . Chronic stents and those treated with anticholinergic agents had fewer symptoms following stent removal. Stent removal by office cystoscopy was associated with a higher level of pain compared with removal by string . Pretreatment with a single dose of a nonsteroidal anti-inflammatory agent prior to stent removal can reduce the severity of pain .
Stent exchange — For polymer stent exchange, the distal coil of the stent is externalized outside the urethral meatus. A guidewire is placed through the stent up the ureter until a coil of the wire is seen in the renal pelvis on fluoroscopy. The previous stent is then removed and a 5 Fr ureteral access catheter placed over the wire and up the ureter. The remainder of the procedure is performed similarly to the initial stent placement. Correct placement of the stent is confirmed with fluoroscopy and cystoscope. (See 'Stent exchange/removal' below.)
During exchange of a metal stent, as the metal stent does not have a lumen, we place a guidewire alongside the stent prior to removal so that ureteral access is not lost. One of the major disadvantages of using a metal stent is the possible loss of ureteral access during stent exchange [6,37].
Patient instructions — Patients are instructed that indwelling stents are temporary devices that need to be changed regularly and are removed when no longer needed. Longer-than-recommended indwelling times can lead to serious complications, including severe encrustation, urinary tract infection, or obstruction and potential loss of kidney function. (See 'Complications' below.)
ROUTINE PATIENT CARE — Stents cause symptoms in the majority of patients that include irritative voiding symptoms, suprapubic discomfort, flank pain upon voiding , and hematuria [14,80,81]. The Ureteral Stent Symptom Questionnaire (USSQ) measures stent-related morbidity in five categories that include voiding symptoms, pain, work performance, sexual health, and overall general health. Negative symptoms affecting quality of life and interfering with the ability to work are experienced by approximately 80 percent of stented patients [82-85].
A prospective study evaluated USSQ data from 86 patients with indwelling double-J ureteral stents of different lengths and sizes that were placed for benign disease . Male sex, increasing body mass index (BMI), increasing stent length, and a distal loop location crossing the midline were significantly associated with increasing analgesic requirements, and BMI and distal loop location were significantly associated with an increasing need for anticholinergic treatment. On multivariate analysis, the location of distal stent loop was associated with the most domains of the USSQ at 7 and 28 days after stent placement, and thus, the visualization of distal loop crossing the midline may identify patients at risk for postprocedural morbidity. When this situation is identified on cystoscopy or fluoroscopy at the time of stent placement, the stent should be repositioned.
The Study to Enhance Understanding of Stent-associated Symptoms (STENTS) found that patients undergoing ureteroscopy with ureteral stent placement for the treatment of stones experienced a marked increase in stent-associated symptoms on postoperative day one. Pain intensity decreased by approximately 50 percent by postoperative day five, but interference due to pain remained elevated while the stent was in place. Patient factors (increased age, chronic pain conditions, depressive symptoms) rather than surgical factors were each associated with high pain intensity . Following stent removal, patients may experience lingering pain and/or urinary symptoms, but these generally resolve within 24 hours [76,87].
Irritative symptoms — Irritative symptoms are common in stented patients, with the distal coil of the stent thought to be the major source of symptoms (discussed in the paragraph above). Transmission of pressure to the upper urinary tract via the stent may account for other stent symptoms, such as ipsilateral flank pain on urination . Irritation of the bladder by the stent can lead to voiding symptoms (eg, urgency, frequency), suprapubic pain, or hematuria.
Stent discomfort due to bladder irritation has been treated with anticholinergic medications (eg, oxybutynin, tolterodine), alpha-blockers, or intravesical pharmacologic therapy. Although anticholinergic medications are routinely used for the treatment of ureteral stent-related symptoms and are clinically effective, there are few formal studies. A greater number of trials are available demonstrating the efficacy of selective alpha-1 blockers (eg, tamsulosin, alfuzosin) over placebo, which is discussed in the next paragraph. One trial that compared tolterodine (anticholinergic) to alfuzosin (alpha-blocker) found similar degrees of symptomatic improvement . Thus, we suggest treatment of stent symptoms with anticholinergic medications or alpha-1 blockers rather than intravesical pharmacologic therapy, for which there is no convincing evidence of efficacy [89,90]. Alpha-1 blockade and anticholinergic agents can also be given in combination . However, in one study, the combination of tamsulosin and tolterodine did not improve urinary symptoms more than tamsulosin monotherapy .
Multiple trials have shown significant improvements in stent-related urinary symptoms with selective alpha-1 blockade (eg, tamsulosin, alfuzosin) [88,89,93-101]. A systematic review identified 12 trials that evaluated the use of alpha blockers for the treatment of ureteral stent symptoms. A meta-analysis of four placebo-controlled trials involving 341 patients found that alpha blockers were associated with significant decreases in urinary symptoms measured using the USSQ (mean difference [MD] -6.76, 95% CI -11.52 to -2.00) and pain (MD -3.55, 95% CI -5.51 to -1.60) . The most common adverse effects associated with alpha-blockers were dizziness, headache, hypotension, nausea, and vomiting, but discontinuation of the medication due to adverse effects was not needed. As examples, the larger trials for alfuzosin and tamsulosin are summarized briefly below:
●In one of the larger trials, 100 patients were randomly assigned to receive alfuzosin (10 mg by mouth once daily) or placebo for a period of four weeks following stent placement . Significantly fewer patients in the alfuzosin group reported pain compared with patients who received placebo (44 versus 66 percent), and significantly better USSQ scores were also found in the alfuzosin group (22 versus 28, respectively).
●Following ureteroscopic stone removal and placement of a double-J ureteral stent, 146 patients were randomly assigned to receive placebo or 0.4 mg of tamsulosin once daily for two weeks . Significant improvements were found in the treated group for overall pain (visual analog scale; 1.52 versus 4.01), voiding flank pain (1.93 versus 3.3), frequency (International Prostate Symptom Scale [IPSS]; 1.55 versus 3.7) and urgency (IPSS; 1.43 versus 3.82), nocturia (IPSS; 0.65 versus 2.01), and quality of life (IPSS; 1.6 versus 4.21) compared with placebo.
In our practice, we will generally prescribe both an anticholinergic medication and an alpha-blocker to patients with a ureteral stent. We ask patients to decide whether to take no, one, or both medications depending on their symptoms post-stent placement. Patients have wide variation with regard to irritative voiding symptoms; some patients have no symptoms and thus do not require any medication, while others have significant symptoms including urinary frequency/urgency or suprapubic discomfort, for which they may need both medications. The side effects of the medications may also influence which medication we use. As an example, a patient who has problems with constipation should be started on tamsulosin first as anticholinergics can cause constipation. Thus, it is important to discuss the side effects of both classes of medications with patients before making a decision. For older men, we generally start an alpha-blocker first as it may also help with voiding symptoms, owing to its effect on the prostate.
Other medications that are being tested and may alleviate stent-related symptoms include mirabegron and sildenafil citrate [102,103]. Mirabegron may have a beneficial effect on pain and urinary symptoms due to ureteral stents, although the evidence is based on low-quality studies . Larger randomized placebo-controlled trials are required to further test their efficacy. Another method to improve bladder-related symptoms is intravesical pharmacologic therapy; however, this approach is limited by the mode of administration. In one randomized trial, the efficacy of oxybutynin, lidocaine, or ketorolac was compared with a control solution following ureteral stent placement for extracorporeal shock wave lithotripsy (ESWL) . Of these agents, only ketorolac was found to significantly reduce flank pain at one hour postoperatively compared with the control solution.
Patients with symptoms that are refractory to treatment should have correct positioning of the stent verified (plain abdominal film, fluoroscopy, cystoscopy) [85,105]. (See 'Stenting technique' above.)
Changes in the design of the stent may lead to improved stent tolerance. To decrease bladder irritation, one design minimizes the amount of stent material residing within the bladder. In a comparative study, those patients stented with a smaller distal loop tail had lower pain scores and pain medication, but the result was not significant . A randomized trial comparing a standard stent design to a stent with a soft tail did not find significant differences between the stents in terms of voiding symptoms or pain, but there were some work- and physical-activity-related advantages .
Pain management — Sources for stent pain and discomfort include irritation of the bladder by the distal curl and flank pain upon voiding due to vesicoureteral reflux. Irritative symptoms can be managed with a combination of anticholinergic agents and alpha-1 blockade. (See 'Irritative symptoms' above.)
Unfortunately, there is no specific treatment to prevent flank pain due to vesicoureteral reflux. Narcotic analgesics may be required, and, at times, stent pain or discomfort may be so intolerable that stent removal is needed. In a double-blinded trial of patients undergoing ureteroscopy with stent placement, nonsteroidal anti-inflammatory drugs were noninferior to narcotics for pain management .
For persistent flank pain, it is important to verify that the stent has not migrated or is not encrusted, causing urinary obstruction. A plain supine abdominal film (ie, KUB) can verify the placement of the stent with adequately positioned proximal and distal curls. Severe stent encrustation can be visualized as deposits on the surface of the stent. Ultrasound can be used to evaluate for hydronephrosis indicative of significant ureteral obstruction. If the cause of the pain is found to be stent migration, encrustation, or obstruction, the stent should be exchanged. (See 'Stent migration' below and 'Stent encrustation' below and 'Stent exchange' above.)
Stent exchange/removal — We remove ureteral stents one week after initial placement to minimize the potential for infectious complications. For patients requiring a chronic indwelling stent, stents are usually exchanged every three months on average (some stents may be changed every six months, or even annually for stents made of newer materials). Chronic indwelling stents with encrustation may require more frequent exchanges. As with initial stent placement, patients found to have a positive urinalysis should be treated with antibiotics whenever possible to sterilize the urine prior to ureteral manipulation. (See 'Antibiotics' above.)
COMPLICATIONS — The main complications associated with ureteral stent placement, which include hematuria, urinary tract infection, stent migration within the urinary tract, stent encrustation, and retained stents, are discussed below. Rare complications include stent migration out of the urinary tract, such as into the inferior vena cava , reflux anuria following removal of bilateral prophylactic ureteral stents , and arterial-ureteral fistula (a rare complication that can occur in patients with vascular reconstruction and chronic stenting) .
Hematuria — Microscopic hematuria occurs in the majority of patients with an indwelling ureteral stent, but, occasionally, gross hematuria can develop. Hematuria is due to irritation of the bladder mucosa by the stent and typically resolves following stent removal.
Urinary tract infection — Patients with ureteral stents are prone to urinary tract infection. Prior to stent placement or stent removal, all patients should receive prophylactic antibiotics to reduce the potential for urinary infection . When signs or symptoms of sepsis or urinary tract infection develop following stent placement, the antimicrobial agent used for treatment should not be the same as that used for antimicrobial prophylaxis. (See 'Antibiotics' above.)
As a foreign body, ureteral stents are often colonized by bacteria. Bacterial colonization of the ureteral stent occurs at approximately two weeks following stent placement, and stent colonization precedes urine colonization and urinary infection . A short course of antibiotics (two to three days) decreases stent colonization . However, long-term therapy does not provide an additional benefit for patients with asymptomatic bacteriuria .
Early stent removal is the most important factor in preventing infectious stent complications since longer indwelling times are associated with an increasing risk for urinary tract infections and sepsis [111,113]. Patients with diabetes mellitus and chronic renal failure are at a higher risk for urinary tract infections, and these patients should have shorter stent retention times and careful follow-up to monitor for the development of infectious complications [114,115]. (See 'Routine patient care' above.)
Stent migration — The proximal and distal curls of the stent are designed to minimize the likelihood of stent migration. The incidence of stent migration is approximately 4 percent [116,117]. Inadequate stent length is the most common cause of proximal stent migration, which requires ureteroscopy to retrieve the stent. Correct positioning of an appropriately sized stent with a full curl in the renal pelvis and bladder (image 1) is the simplest measure to reduce the likelihood of stent migration . (See 'Stenting technique' above.)
Recurrent symptoms in a patient treated for ureteral stricture may indicate that the stent has migrated above or below the treated stenotic region. Patients with stent migration may have symptoms of urinary obstruction (de novo or recurrent) that can present as flank pain or urinary tract infection. When stent migration is suspected, plain films of the abdomen are obtained to examine stent positioning and may demonstrate an inadequate ureteral coil either proximally or distally depending upon the direction of stent migration.
If obstructive symptoms and urinary infection are not present, the stent can be electively removed or exchanged in the office setting. Otherwise, the patient should be treated with antibiotics and undergo urgent stent exchange. (See 'Stent exchange' above.)
Stent encrustation — The incidence of stent encrustation is not precisely known, since this entity is not easily quantified and most studies evaluating it are small retrospective studies. Stent encrustation is the deposition of mineral crystals (uric acid or calcium oxalate) onto the surface and lumen of the stent (picture 4). Calcium phosphate and ammonium-magnesium-phosphate (ie, struvite) can also precipitate but require a higher pH level, which can occur in association with certain urinary tract infections (urea-splitting bacteria produce ammonia) .
The mechanism of stent encrustation is a complex process. After a stent is placed, it is covered by a conditioning film made of glycoproteins specific to a patient's urinary composition and tissue. At this point, one of three outcomes can occur: (1) the stent remains unchanged, (2) the stent can be further coated with a bacterial biofilm (predisposing to infection and sepsis), or (3) the stent can develop encrustation . Severe encrustation with stone formation can lead to urinary tract obstruction, urinary sepsis, and potential loss of kidney function. (See "Kidney stones in adults: Struvite (infection) stones" and "Kidney stones in adults: Uric acid nephrolithiasis" and "Kidney stones in adults: Epidemiology and risk factors".)
The most important risk factor for stent encrustation is stent indwelling time [55,119]. Other factors include a history of urolithiasis, high concentration of dissolved urinary materials, type of stent material, presence of bacterial colonization, and pregnancy [120-122]. (See 'Stent exchange/removal' above and 'Ureteral stents during pregnancy' below.)
Managing the encrusted stent — Encrustation that is present on the proximal and distal stent coils complicates stent removal since the coil will be resistant to straightening (picture 4). A supine abdominal film (KUB) should be obtained in patients who have had a stent in place for a prolonged period of time to identify areas of encrustation before attempted removal. If encrustation is present, stent removal should be performed under anesthesia with fluoroscopic guidance .
Successful treatment of encrusted ureteral stents requires careful planning and a multimodal endourologic approach . Stent fragmentation can occur during the removal of these stents . Any fragments that result from stent removal should be retrieved whenever possible, though some may be allowed to pass passively. If endourologic options fail to achieve stent removal, open surgery will be needed .
To remove an encrusted stent, a rigid grasper is passed via a cystoscope and used to first break the deposits off the distal coil and then to grasp and gently pull the stent out under fluoroscopic guidance. It is important to avoid significant traction on the stent, which can lead to ureteral trauma, ureteral avulsion, or stent fracture and fragmentation . If the stent cannot be removed with gentle traction, a guidewire is passed through the stent to unfurl the proximal coil. Sometimes, the guidewire cannot be placed through the center of the stent due to encrustation of the lumen, or the proximal coil may not straighten. Under these circumstances, advanced interventional techniques will be needed, such as advancing a sheath over the encrusted stent . When encrustation of the distal stent is associated with stone formation, cystolitholapaxy can be performed . Cystolitholapaxy refers to the use of a specialized instrument that is advanced through the cystoscope to crush the stones either mechanically or with the use of ultrasound.
Calcification along the ureteral component of the stent can be treated with retrograde ureteroscopy and laser lithotripsy. A safety wire is passed alongside the encrusted stent to maintain ureteral access. If the ureteroscope cannot be passed easily over the wire alongside the stent, then shock wave lithotripsy is performed during a second outpatient procedure with the shocks focused on the areas of maximal encrustation . Ureteroscopy is then repeated to remove the stent. In one small retrospective study, a combination of ureteroscopy and lithotripsy successfully removed encrusted stents in 86 percent of patients in an average of 1.86 procedures .
For severe encrustation or calcification of the proximal stent, percutaneous nephrolithotomy in conjunction with antegrade ureteroscopy is preferred. The nephrolithotomy allows direct access to the renal pelvis to manage the encrusted proximal stent, and ureteroscopy facilitates stent removal [8,126,130].
Retained stent — Retained ureteral stents are generally rare and occur when a patient does not follow up for stent removal .
To reduce the number of "forgotten" stents, a stent registry is advocated . Automated data collection through an electronic medical record system can facilitate easy identification of "forgotten" stents before potential complications ensue . The use of computerized tracking significantly lowers the incidence of overdue ureteral stent exchanges. In one trial, missed stent exchanges were reduced from 12.5 to 1.2 percent over one year . For patients with a retained stent, imaging of the stent with an abdominal plain film should be performed to determine the degree of encrustation present prior to attempted removal. (See 'Stent encrustation' above.)
URETERAL STENTS DURING PREGNANCY — The incidence of urolithiasis during pregnancy is the same as in the general population. Treatment is generally conservative, with 70 percent of stones passing spontaneously. Percutaneous nephrostomy, ureteroscopy with lithotripsy, or ureteral stent placement may be indicated if conservative management fails. The management of urolithiasis in pregnancy is discussed in detail elsewhere. (See "Kidney stones in adults: Kidney stones during pregnancy".)
Because radiation exposure to the fetus is a concern during pregnancy, ureteral stents can be placed with ultrasound guidance instead of with fluoroscopy . If ultrasound is not available, pulsed fluoroscopy will minimize radiation exposure.
Frequent stent changes, every four to six weeks, are generally needed to avoid heavy encrustation in pregnant patients [136-138]. The exact cause of increased encrustation during pregnancy is unknown, though the physiologic state of absorptive hypercalciuria and hyperuricosuria associated with pregnancy may be contributing factors. Urinary tract infections or asymptomatic bacteriuria during pregnancy may also play a causative role [136,137]. (See 'Stent encrustation' above and "Urinary tract infections and asymptomatic bacteriuria in pregnancy".)
SUMMARY AND RECOMMENDATIONS
●Indications for ureteral stents – Ureteral stents are functionally used to reestablish or maintain the patency of the ureter. Ureteral stents are indicated for the management of ureteral obstruction, to protect a ureteral anastomosis prophylactically prior to extracorporeal shock wave lithotripsy (ESWL), following complicated ureteroscopy, or prior to surgery to assist with intraoperative identification of the ureter. (See 'Indications for stent placement' above.)
●Stent material and design – Most ureteral stents consist of hollow tubes with multiple side holes and proximal and distal ends that are typically curled. The majority of ureteral stents are made of silicone-based materials, though metal stents are available when increased radial force is needed (eg, malignant ureteral obstruction). A variety of coatings are also available to ease placement of stents and decrease bacterial colonization of the stent. (See 'Stent design' above.)
●Stent placement – Ureteral stents are generally placed by a urologist in the operating room (outpatient setting) as fluoroscopy is needed in order to verify accurate stent placement. (See 'Stent placement' above.)
•Prophylactic antibiotics – Prior to ureteral stent placement, we recommend prophylactic antibiotics based upon indirect evidence supporting the use of antimicrobial prophylaxis prior to cystourethroscopy with manipulation (Grade 1B). A single dose of a fluoroquinolone given within one hour of the procedure should be sufficient. Other antibiotics may be chosen depending upon local susceptibility patterns or recent prior antimicrobial treatment. (See 'Antibiotics' above.)
•Surgical technique – Ureteral stents are placed, exchanged, or removed with a cystoscope with or without fluoroscopic guidance using endourologic techniques. Correct positioning of the stent is confirmed by the presence of a full stent coil in the renal pelvis and full stent coil in the bladder (ie, double pigtail stent). In patients who are pregnant, ultrasound can be used to verify the positioning of the proximal curl. (See 'Stenting technique' above and 'Ureteral stents during pregnancy' above and 'Stent exchange' above.)
●Stent exchange or removal – We remove ureteral stents one week after initial placement to minimize the potential for infectious complications. For patients requiring a chronic indwelling stent, stents are usually exchanged every three months on average (some stents may be changed every six months, or even annually in stents made of newer materials). Chronic indwelling stents with encrustation may require more frequent exchanges (eg, every two months). Patients who are pregnant may require stent exchange every six weeks given the higher likelihood of encrustation. (See 'Stent exchange' above and 'Managing the encrusted stent' above and 'Ureteral stents during pregnancy' above.)
●Care of patient with stent – Following stent placement, patients can resume their normal activities. They are informed that irritative symptoms are common following ureteral stent placement. Irritation of the bladder from the distal stent coil can lead to voiding symptoms of urgency or frequency, suprapubic pain, or hematuria. Patients are also instructed of the importance of follow-up for stent exchanges and removal of the stent when it is no longer needed. Prolonged stent indwelling times can lead to serious complications including encrustation, urinary tract infection, or urinary obstruction and potential loss of kidney function. (See 'Patient instructions' above and 'Complications' above.)
•For irritative symptoms following ureteral stent placement, we suggest treatment with anticholinergic agents or selective alpha-1 blockers (eg, tamsulosin, alfuzosin), rather than intravesical pharmacologic therapy (Grade 2B). Anticholinergic agents and alpha-1 blockade can also be given in combination. (See 'Irritative symptoms' above.)
•Patients with ureteral stents are prone to urinary tract infection. Bacterial colonization of the ureteral stent is common and precedes bacteriuria and infection. Longer indwelling stent duration is associated with an increasing risk for urinary tract infections. Therefore, early stent exchange or removal is important for preventing infectious complications. (See 'Urinary tract infection' above.)
•Stent migration occurs in approximately 4 percent of patients with ureteral stents. Presenting symptoms include pain and/or urinary obstructive symptoms. When stent migration is suspected, plain films of the abdomen should be obtained to evaluate the position of the stent. If obstructive symptoms and urinary infection are not present, the stent can be electively removed or exchanged in the office setting. (See 'Stent migration' above.)
•Stent encrustation is caused by the deposition of uric acid, calcium oxalate, or struvite onto the surface of the stent. Severe encrustation with stone formation can lead to urinary obstruction, urinary sepsis, and potential loss of kidney function. The most important risk factor for stent encrustation is indwelling stent duration. Other risk factors include a history of urolithiasis, high concentration of dissolved urinary materials, type of stent material, presence of bacterial colonization, and pregnancy. Encrusted stents are managed with a combination of endourologic techniques, which can include cystoscopy, antegrade or retrograde ureteroscopy, cystolitholapaxy, percutaneous nephrolithotomy, and laser lithotripsy. (See 'Stent encrustation' above.)
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