What Are the Side Effects of a Kidney Stent?

Ureteral stents, sometimes loosely called kidney stents, cause side effects in a striking majority of patients. Research puts the figure at over 80 percent, with symptoms ranging from frequent urination and flank pain to blood in the urine and a persistent sense of bladder urgency.¹ For most people, those effects are tolerable and temporary. But the sheer variety of complaints and the degree to which they disrupt daily life often catch patients off guard, especially when no one warned them beforehand.

The Most Common Side Effects

The stent is a thin, flexible tube placed inside the ureter, the narrow channel connecting your kidney to your bladder. One curled end sits in the kidney and the other curls inside the bladder. That bladder coil is the main source of trouble. It rubs against the bladder wall, triggering many of the same sensations as a urinary tract infection even when no infection is present.

The most widely reported symptoms include:

Frequency and urgency: You feel the need to urinate far more often than normal, and the urge comes on suddenly.
Dysuria: A burning or stinging sensation when urinating.
Flank and suprapubic pain: Aching on the side of the stented kidney, sometimes radiating to the lower abdomen, especially during or just after urination.
Hematuria: Blood in the urine, which can range from a faint pink tinge to visibly red, particularly after physical activity.
Incomplete emptying: A lingering feeling that your bladder has not fully drained.
Incontinence: Some patients leak small amounts of urine, especially under the sudden urgency the stent provokes.

These symptoms tend to be worst during the first week after placement and may improve somewhat as the body adjusts, though many people report persistent discomfort for the entire time the stent is in place.¹ The severity is enough that stents are widely described as being poorly tolerated and capable of substantially impairing quality of life.²

Why Some People Have Worse Symptoms Than Others

Not everyone with a stent suffers equally, and body size appears to be one factor. A study evaluating the position of double-J stents on abdominal X-ray found that in shorter patients, the bladder coil was more likely to cross over to the opposite side of the bladder. That contralateral positioning was associated with higher symptom scores. Men and women above average height had a lower risk of the stent migrating to the contralateral side and reported lower symptom scores overall.³

Stent diameter and design also play a role, though the evidence is mixed. A narrative review of the research found that symptoms did not simply vanish when smaller-diameter stents were used, though some studies noted fewer irritative sensations with thinner stents. Larger diameters, on the other hand, consistently made pain worse. Stents that incorporate a tethered string or a loop rather than a traditional pigtail curl tended to produce less pain and fewer urinary symptoms in several trials.⁴ But stent rigidity, which varies by material, had conflicting results across studies, with one landmark trial finding no symptom differences between stiff and soft materials and another concluding that softer stents caused fewer problems.

Infection Risk

Any foreign device in the urinary tract increases the chance of infection, and stents are no exception. Bacteria can colonize the stent surface and form a biofilm, a thin layer of microorganisms embedded in a protective matrix that makes them harder for the immune system and antibiotics to reach.⁵ Once a biofilm develops, it can serve as a reservoir for urinary tract infections.

A study examining bacterial colonization in patients with ureteral stents found that about 19 percent of stents showed positive bacterial cultures at the time of removal, while about 9 percent of corresponding urine samples tested positive. The most common bacteria found on colonized stents were E. coli, accounting for roughly a third of isolates, followed by Pseudomonas aeruginosa at about a fifth.⁶ Biofilm formation on the stent can also contribute to encrustation, the mineral buildup discussed in the next section, because the bacterial layer creates a surface that crystals cling to more easily.⁷

Encrustation and Why Dwell Time Matters

Encrustation is the buildup of mineral deposits, mainly calcium-based crystals, on the stent surface. It is one of the most significant complications of long-term stenting. The process is driven by multiple factors: how long the stent stays in the body, the patient’s individual urine chemistry, biofilm formation, and the type of material the stent is made from.⁸ A heavily encrusted stent can obstruct urine flow, cause pain, and make removal significantly more difficult.

Not all stent materials encrust at the same rate. Comparative testing of five common materials found that silicone was the least prone to mineral buildup, followed by polyurethane. Hydrogel-coated polyurethane stents performed the worst in the encrustation rankings.⁹ These differences matter most for patients who need stents for weeks or months rather than days. The correlation between time in the body and degree of encrustation is strong and well-documented, which is a large part of why urologists stress the importance of not leaving a stent in longer than planned.

Forgotten Stents and Their Consequences

A “forgotten stent” is one that stays in the body well beyond its intended removal date, sometimes for months or years. This happens more often than you might expect, usually because of poor follow-up, patients missing appointments, or miscommunication between providers. The consequences are serious.

One review of forgotten stent cases found that 60 percent of patients presented with urinary tract infections, about a quarter had elevated creatinine levels suggesting kidney damage, and imaging showed mineral encrustation on nearly a quarter of stents. About 13 percent of stents had physically broken apart inside the body. Fewer than 40 percent of these forgotten stents could be removed with a simple cystoscopy; the rest required more complex procedures including ureteroscopy, percutaneous kidney surgery, bladder stone crushing, or even open surgery.¹⁰

A single-center analysis painted a similarly alarming picture: the average time a forgotten stent stayed in place was over three years, with some left for as long as 11 years. Nearly three-quarters of those patients had moderate to severe encrustation, a fifth had stent fragmentation, and one patient lost kidney function on the affected side entirely. The longer the stent stayed in, the worse the encrustation became, with a very strong statistical correlation between dwell time and severity.¹¹ If you have a stent, keep your removal appointment. It is one of the most consequential follow-through decisions in routine urology.

Stent Migration

Stents are designed to stay in place thanks to their curled ends, but they sometimes shift. Migration can be proximal (upward toward the kidney) or distal (downward into the bladder). Proposed explanations for proximal migration include prolonged dwell time, stent movement in sync with kidney motion during breathing, the presence of hydronephrosis, and a ureteral stone alongside the stent acting like a ratchet mechanism that allows only upward movement.¹² A migrated stent can cause increased pain, fail to keep the ureter open, and complicate removal. In some cases, a second procedure is needed to retrieve a stent that has wandered out of position.

Medications That Help With Stent Symptoms

Doctors have several drug classes they can prescribe to take the edge off stent-related discomfort. None of them eliminate symptoms entirely, but the evidence supports meaningful relief for many patients.

Alpha-Blockers

Alpha-blockers like tamsulosin, alfuzosin, and terazosin work by relaxing the smooth muscle of the ureter and bladder neck. A meta-analysis pooling direct and indirect comparisons found that alpha-blockers as a class reduced urinary symptom scores, pain, and general health impairment compared with controls.¹³ A prospective trial showed that patients not on tamsulosin had significantly worse urinary symptoms and pain scores one week after stent placement, alongside lower overall quality-of-life ratings.¹⁴ Alpha-blockers are probably the most widely used drug for stent symptoms, in part because they are inexpensive and most urologists are already comfortable prescribing them.

Mirabegron and Solifenacin

Mirabegron, a bladder-relaxing drug originally developed for overactive bladder, has also shown benefit. A controlled trial found that patients taking mirabegron had lower daytime frequency, less nocturia, less urgency, less flank and abdominal pain, and better overall quality-of-life scores compared to a control group during the stenting period.¹⁵ Analgesic use was also lower in both tamsulosin and mirabegron groups compared to placebo in a head-to-head trial.¹⁶

A network meta-analysis comparing mirabegron, tamsulosin, and solifenacin (an antimuscarinic) found all three produced statistically significant improvement in urinary symptoms compared with placebo, with no major differences between them. Solifenacin ranked slightly highest for urinary symptom relief, mirabegron was close behind, and tamsulosin came in third.¹⁷ For patients with particularly stubborn symptoms, combining solifenacin and mirabegron together has shown improvements beyond what solifenacin alone achieves, including further reductions in urgency, frequency, and incontinence episodes at both two and four weeks.¹⁸

Local Anesthetic Approaches

Given how much stent pain dominates the patient experience, researchers have tried injecting local anesthetics directly into the ureter at the time of stent placement. The results have been disappointing. A randomized phase 2 trial of lidocaine instilled directly into the ureter found no significant improvement in pain or voiding symptoms after stented ureteroscopy compared with placebo.¹⁹ Intravesical ketorolac, an anti-inflammatory agent instilled into the bladder, did show a brief reduction in discomfort at the one-hour mark in a separate trial, but this is not a practical long-term solution.²⁰

Does Stent Removal Hurt?

Stent removal is a common source of anxiety, and how it feels depends largely on the method used. Some stents are placed with an attached extraction string that dangles outside the body through the urethra. Patients or their doctors can pull the string to remove the stent without any procedure at all. Stents without a string require a brief cystoscopy, in which a small scope is passed through the urethra to grab and withdraw the device.

A systematic review and meta-analysis of randomized trials found that string-based removal caused significantly less pain than cystoscopic removal. The benefit was particularly clear in women, while men did not show a statistically significant pain reduction with string removal.²¹ Infection rates were similar regardless of whether a string was used.

The trade-off with string stents is a higher risk of early dislodgement. A pooled analysis found that dislodgement was significantly more common in the string group, though overall complication rates and symptom questionnaire scores during the stenting period were not significantly different between the two approaches.²² String-stent complication rates in one large series were about 13 percent, nearly identical to the 14 percent rate in the no-string group.²³ In practice, many urologists reserve string stents for patients who need the stent for only a few days and can reliably manage the string without accidentally pulling it out too early.

Rare but Serious Complications

The vast majority of stent side effects are uncomfortable rather than dangerous. But in rare cases, particularly with prolonged stenting in patients who have had pelvic surgery or abdominal radiation, a dangerous complication called a ureteroarterial fistula can develop. This is an abnormal connection between the ureter and a nearby artery. It can cause sudden, massive blood in the urine and is potentially life-threatening.²⁴ This complication is extremely uncommon and is mostly a concern for patients with chronic indwelling stents and a history of radiation or vascular surgery in the pelvis. If you are in that category and develop sudden heavy bleeding, it warrants emergency evaluation.

Stents in Children

Children need ureteral stents for many of the same reasons adults do, including kidney stones and structural blockages like ureteropelvic junction obstruction. They experience the same types of side effects: pain, irritative voiding symptoms, and urinary tract infections.²⁵ But children face an added challenge. Stent removal typically requires a second round of anesthesia, which carries its own risks and costs. Newer stent designs, including biodegradable options, have shown promise in reducing the need for that second procedure.²⁶ For parents, the practical takeaway is that pediatric stent complications mirror adult ones, but the conversation about stent type and removal method is worth having with the surgeon beforehand.

Biodegradable Stents and New Materials

The fact that ureteral stents cause so much discomfort has driven considerable research into better designs. One of the most interesting frontiers is the biodegradable stent, which dissolves on its own over a predetermined period. The appeal is obvious: no removal procedure, no risk of a forgotten stent, and potentially less time spent with a foreign body irritating the bladder. Researchers are exploring stent coatings tailored for specific roles, including surfaces that resist bacterial adhesion, inhibit mineral deposition, deliver anti-inflammatory drugs locally, or even carry anti-tumor agents for patients with malignant obstructions.²⁷

The challenge with biodegradable stents is controlling the rate of degradation. Dissolve too quickly and the ureter loses support before it has healed. Dissolve too slowly and you are back to the same problems as a conventional stent. Most biodegradable designs are still in preclinical or early clinical stages, but the pace of materials science research in this area has accelerated. For now, the standard polyurethane and silicone stents remain the clinical workhorses, but patients asking their urologist about newer options is entirely reasonable, especially if a longer stenting period is anticipated.

Meanwhile, modifications to conventional stent geometry continue to be studied. Stents with a string or loop design rather than a traditional pigtail curl in the bladder have produced less pain and fewer urinary symptoms in several trials, though not every study agrees on the magnitude of benefit.⁴ Biomaterial innovations that reduce biofilm adhesion are another active area. Since bacterial colonization is a precursor to both infection and encrustation, a stent surface that resists biofilm could address two problems simultaneously.⁵ The field is clearly moving in the right direction, but the current reality is that most patients will still feel their stent and be glad when it comes out.

1
PubMed Central. Ureteral stent discomfort: Etiology and management
2
Research Reports in Urology. A Customized Reinforced 8-French Ureteral Stent with End-Piece to Decrease Ureteral Obstruction and Alleviate Stent-Related Symptoms
3
Indonesian Journal of Urology. Association Between Body Height and Double J Stent Intravesical Position and Its Relation with the Indonesian Version of Ureteral Stent Symptom Questionnaire (USSQ)
4
PubMed Central. Ureteral stents: A brief narrative review of the different polymeric types, their characteristics, and their connection to stent-related symptoms
5
PubMed Central. Problems and solutions of stent biofilm and encrustations: A review of literature
6
Bionatura. Risk factors in bacterial colonization of internal ureteral stent
7
Frontiers in Urology. The interplay between bacterial biofilms, encrustation, and wall shear stress in ureteral stents: a review across scales
8
PubMed. Ureteral Stent Encrustation: Epidemiology, Pathophysiology, Management and Current Technology
9
PubMed. Comparative assessment of ureteral stent biomaterial encrustation
10
African Journal of Urology. Forgotten ureteral stents: Risk factors, complications and management
11
International Surgery Journal. Management of forgotten double J stent and its complications: a single center experience
12
PubMed Central. Ureteral stent complications – experience on 50,000 procedures
13
PubMed Central. Efficacy of α-blocker in improving ureteral stent-related symptoms: a meta-analysis of both direct and indirect comparison
14
PubMed. Effect of tamsulosin in preventing ureteral stent-related morbidity: a prospective study
15
PubMed Central. The role of mirabegron in relieving double-J stent-related discomfort: a randomized controlled clinical trial
16
PubMed. Does tamsulosin or mirabegron improve ureteral stent-related symptoms? A prospective placebo-controlled study
17
PubMed Central. Comparing efficacy and safety of mirabegron, tamsulosin, and solifenacin in ureteral stent-related symptoms: outcomes from a network meta-analysis
18
PubMed Central. Efficacy and safety of combination of mirabegron and solifenacin in patients with double-J stent related overactive bladder: a prospective study
19
PubMed Central. Intraureteral lidocaine for ureteral stent symptoms post-ureteroscopy: A randomized, phase 2, placebo-controlled trial
20
PubMed. Double-blind randomized controlled trial assessing the safety and efficacy of intravesical agents for ureteral stent symptoms after extracorporeal shockwave lithotripsy
21
PubMed Central. Effects of ureteral stent removal using an extraction string following ureteroscopic lithotripsy: a systematic review and meta-analysis of randomized controlled trials
22
PubMed Central. Pooled analysis of efficacy and safety of ureteral stent removal using an extraction string
23
PubMed Central. The use of a string with a stent for self-removal following ureteroscopy: A safe practice to remain
24
PubMed. An uncommon cause of gross hematuria: two cases of ureteroarterial fistula
25
Urinary Stents. Pediatric Ureteral Stents
26
PubMed. Ureteral Stents in the Management of Pediatric Urolithiasis: A Systematic Review
27
PubMed Central. Recent development and future application of biodegradable ureteral stents