Ureteric stents, also known as double J stents or retrograde ureteric stents, is a urological catheter that has two "J-shaped" (curled) ends, where one is anchored in the renal pelvis and the other inside the bladder.
Stents are used for the free passage of urine from the kidney to the bladder, in adverse conditions such as postoperative urologic procedures, and previously for lithotripsy and ureteral obstructions.
Ureteric stents may be placed from an antegrade approach by an interventional radiologist or a retrograde approach by a urologist. Stent placement may replace a percutaneous nephrostomy that has been performed in the acute setting. This is popular with patients as it 'internalises' the method of obstruction bypass without the negatives of a nephrostomy.
Stents may be used for a short of long term period depending on the indication:
- obstruction from urolithiasis
- malignant obstruction (typically pelvis malignancies)
- benign strictures
- retroperitoneal fibrosis
The majority of stents are plastic, but metallic stents are now available for use in malignancy to reduce the chance of in growth into the stent. It is a trade off as these stents are significantly more expensive than traditional stents.
A variety of delivery systems exist:
- pusher mechanism
- string release
- sheath (similar to a IVC filter)
Equipment required includes:
- angled 0.035 150 cm hydrophilic wire
- 145 cm 0.035 Amplatz super stiff wire
- 8F sheath
- ureteric stent (typically 6F, 28 cm)
- 8F catheter (for covering nephrostomy)
- analgesic and sedative medications (e.g. pethidine, midazolam)
Post procedural care
- one end of the stent may migrate or in rare circumstances completely dislodge
- urosepsis following the process of insertion
- failure to insert, typically due to a stricture that is impassable
- blockage (although the urine may also pass outside, not through the tube)
- encrustation/calcification - making replacement difficult
Stents are typically left for a maximum of 3-6 months. If long-term stents are required exchanges (replacement) are usually due to encrustation.
History and etymology
Somewhat surprisingly the word 'stent' is actually an eponym, originally named after Charles Stent (1807-1885), a largely-forgotten British dentist. He invented an improved material for forming dental impressions, and set up a company to manufacture it. During the Great War, J F Esser, a Dutch surgeon used a mold of Stent's Compound as a fixative for skin grafting in injured infantrymen. This innovative use, was rapidly adopted into practice, and stenting as a concept rapidly segued into multiple specialties.