Yes, Ureteral (Renal) Stents Are Designed to Allow Some Urine Leakage—This Is Normal Function
Ureteral stents, including double-J stents, are specifically designed with side holes along their length and function by allowing urine to flow both through the internal lumen AND around the outside of the stent via reflux—this is intentional, not a malfunction. The stent's primary purpose is to maintain ureteral patency and facilitate drainage, not to create a watertight seal 1.
How Ureteral Stents Actually Work
The double-J (DJ) stent design includes:
- Multiple side holes along the stent body that permit bidirectional urine flow
- Coiled ends (the "J" shapes) that anchor in the renal pelvis and bladder
- An open internal lumen that allows direct urine passage
Urine flows through three pathways when a stent is in place:
- Through the internal lumen of the stent itself
- Through the side holes into the periureteral space
- Around the outside of the stent between the stent and ureteral wall
This design intentionally creates vesicoureteral reflux—urine can flow backward from the bladder into the kidney when bladder pressure increases (during voiding, coughing, straining). This is why patients with stents often experience bothersome lower urinary tract symptoms and flank discomfort 2, 3.
Clinical Context: When "Leaking" Becomes Pathologic
While the stent's design permits urine flow around it, you must distinguish between normal stent function and true ureteral injury with extravasation:
Normal stent function:
- Urine drains into the bladder (even if some refluxes back)
- No urinoma formation
- No periureteral fluid collections
- Stable or improving hydronephrosis
Pathologic ureteral leak requiring intervention 1, 2, 1:
- Contrast extravasation outside the urinary tract on imaging
- Enlarging urinoma
- Urinary ascites
- Persistent fever despite stent placement
- Worsening pain or ileus
- Development of ureteral fistula
When Stents Are Used for Actual Leaks
When managing true ureteral injuries or leaks, stents serve as internal drainage to divert urine preferentially through the stent lumen rather than through the injury site 2. The ACR Appropriateness Criteria (2020) clearly state that for ureteral leaks after surgery, retrograde ureteral stenting or percutaneous nephrostomy are appropriate first-line interventions 2.
The AUA Urotrauma Guideline (2014) recommends that clinicians should perform urinary drainage in the presence of complications such as enlarging urinoma, fever, increasing pain, ileus, fistula or infection, achieved via ureteral stent and may be augmented by percutaneous urinoma drain, percutaneous nephrostomy or both 1.
Common Pitfall: Confusing Stent Function with Stent Failure
The most common misconception is assuming that any urine outside the stent lumen represents stent failure. In reality:
- Stents decompress the collecting system by providing a low-resistance pathway
- Some periureteral urine flow is expected and normal
- The stent prevents complete obstruction while allowing healing
- For actual injuries, the stent reduces leak severity even if it doesn't eliminate it completely 4, 5
Monitoring Stented Patients
Follow patients with imaging (ultrasound or CT) to assess:
- Resolution or stability of hydronephrosis
- Absence of enlarging fluid collections
- No new urinomas
- Clinical improvement (decreased pain, resolution of fever)
If hydronephrosis worsens, new collections develop, or symptoms persist despite stenting, the stent may be malpositioned, occluded, or inadequate for the degree of injury—requiring either stent exchange, upsizing, or addition of percutaneous nephrostomy 1, 2, 1.
Infection Risk with Stents
A critical caveat: stents increase urinary tract infection risk significantly 3, 4, 5, 6. Studies show UTI rates of 20-51% in stented patients versus 17-19% in non-stented patients 4, 5, 6. This occurs because:
- Stents create a foreign body nidus for bacterial colonization
- Reflux facilitates bacterial ascent
- Biofilm formation occurs rapidly
For procedures involving stent placement or exchange, prophylactic antibiotics covering uropathogens (ceftriaxone or ampicillin-sulbactam, NOT just cefazolin) reduce serious septic complications from 50% to 9% in high-risk patients 3.