Indwelling ureteral stents to the urologist is as commonplace as the stethoscope for the cardiologist and the reflex hammer to the neurologist.
However, unlike these routine tools of the trade, stents can be aggravating and bothersome for both patient and urologist. While a perfect stent has not been designed, they are indispensible devices that are used everyday in our field. They have unique qualities that make them both diagnostic and therapeutic.
As they pertain to chronic urinary obstruction, stents are used when definitive surgical management is either contraindicated or is against patient desires. Obstruction can be divided into intrinsic and extrinsic. The former arises in cases such as ureteropelvic junction obstruction (UPJ), ureteral tumor, or ureteral stricture disease.
The most effective management for UPJ obstruction is surgical correction of the defect. However, if the patient is infirm and cannot undergo definitive repair, chronic stenting is a viable alternative. Similarly, ureteral tumor or stricture can be addressed surgically and may obviate the need for chronic stenting. Many of these patients have significant co-morbidities making surgery high risk.
Extrinsic ureteral compression can arise from a host of conditions, including malignancy (gynecological, colorectal, or urinary), retroperitoneal fibrosis, and endometriosis. It also can be a complication of radiation therapy. The treatment of choice in these patients is addressing the primary offender and relieving the obstruction. Again, some of these patients are not adequate surgical candidates and are in need of chronic relief of obstruction to avoid renal demise, pain, and infection.
There are essentially two broad categories of stents: polymer and metal. There are many polymer stents commercially available. They range in length from 8-30 cm and in width from 3-8.5 Fr (3 Fr = 1 mm). The majority are in the shape of a “double-J,” having a loop, or a pigtail at both ends securing them in the renal pelvis and in the bladder.
To minimize bladder symptoms, some stents have loops or thin tails in the bladder. There are stents that have variable lengths; they have multiple loops enabling them to be used for ureters of different length. The biggest drawback of polymer stents in chronic urinary obstruction is the need to change them frequently. Inherent properties that place these stents at risk for encrustation limit the long-term indwelling times for these products.