|A variety of ureteral stents.|
- Intrinsic (or internal) ureteral obstruction – as from kidney stone
- Extrinsic (or external) ureteral obstruction – as from a compressing malignancy
- Post-operatively following ureteroscopic surgery
- Manipulation of a kidney stone
- Biopsy of renal pelvis or ureteral malignancy
- Dilation of a ureteral stricture
EPIDEMIOLOGY OF STENT PAIN & SYMPTOMSStent pain of varying degrees is estimated to affect upwards of 80% of patients having one placed.[1,2] Specific symptoms and estimated incidences include:
- Irritative Voiding Symptoms (most common)
- Frequency (50-60%)
- Urgency (57-60%)
- Dysuria (40%) – discomfort when voiding
- Incomplete Emptying (76%)
- Pain or Discomfort
- Flank (19-32%) – especially at the end of voiding
- Suprapubic (30%)
- Hematuria (25%) – visible blood in the urine
MECHANISMS OF STENT PAIN & SYMPTOMS
|Ureteral stents can allow "reflux" of urine |
from the bladder to the kidney.
Flank pain is believed to be due to reflux of urine from the bladder to the kidney during voiding. While stents are designed to allow urine to flow from the kidney to the bladder, there is no mechanism to prevent urine flowing up from the bladder to the kidney – especially during voiding when bladder pressures can be quite high. Flank pain at the end of voiding is often mild to moderate and not related to stent length or positioning.[11-13] Expectation of flank pain can often alleviate many patient concerns with this phenomenon. Suprapubic pain is most often related to stent position and mechanical irritation of the trigone.
Incontinence is either due to severe mechanisms (as described above), or if the stent migrates distally and bypasses the urethral sphincter, allowing urine to pass unabated out of the bladder.
Hematuria can be related to the underlying process being treated (for example, obstructing kidney stone), result from the surgery (use of a laser or biopsy instruments) or the stent rubbing along the urothelium (lining of the urinary system).
PREVENTING STENT PAIN & SYMPTOMSThe best way to prevent stent pain is to avoid placing a stent. However, it is important to note that most ureteroscopic procedures require a stent to be placed to prevent infection or injury; and failing to place a stent in a patient in whom it is necessary can lead to worse symptoms, hospital readmission, a possible second procedure or permanent injury. The American Urological Association (AUA) Guidelines on the Management of Ureteral Calculi state that "Stenting following uncomplicated ureteroscopy is optional."
Stents come in a variety of lengths and calibers. Choosing an appropriate stent size and positioning appropriately can prevent most significant symptoms. While a number of systems have been developed for adult [5,14,16] and pediatric  patients to predict the "best" stent length for a patient, in general a stent should rest proximally in the renal pelvis and distally curl just into the bladder. While the proximal curl (in the kidney) has no correlation to stent symptoms, a distal curl that crosses the midline in the bladder is associated with more irritative voiding symptoms.
A variety of medications and stent-coating materials have been tried to improve stent symptoms. Local anesthetics have demonstrated no benefit  while some stents coated with antibiotics, made of less irritative materials or of tapered design have demonstrated less discomfort in early studies.
TREATING STENT PAIN & SYMPTOMSA number of medications and routes of administration have been used to treat stent symptoms. A number of intravesical medications (given in the bladder) have demonstrated mixed results with no clear benefit. The best studied medications for stent discomfort include the alpha-blockers afluzosin,, tolterodine and tamsulosin. A number of studies have demonstrated improved symptoms, decreased use of pain medications, better sleep and quality-of-life with alpha blockers were compared to placebo.[19-22] Another study failed to demonstrate a benefit to the anticholinergic, oxybutynin, but a small benefit to phenazopyridine (pyridium).
- Many urologic conditions and procedures necessitate the use of ureteral stents.
- Symptoms related to stent placement can affect upwards of 80% of patients with the most common symptoms being irritative voiding symptoms and pain.
- Most symptoms related to an indwelling stent are related to mechanical irritation.
- Therefore, stent symptoms are best managed by:
- Placing a stent only when needed
- Placing a stent that is properly sized and positioned for the patient
- Using medications that mitigate the reaction of the urinary system to the stent
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