A ureteral stent, sometimes as well called ureteric stent, is a thin tube inserted into the ureter

Ureter

In human anatomy, the ureters are muscular tubes that propel urine from the kidneys to the urinary bladder. In the adult, the ureters are usually long and ~3-4 mm in diameter....

 to prevent or treat obstruction of the urine

Urine

Urine is a typically sterile liquid by-product of the body that is secreted by the kidneys through a process called urination and excreted through the urethra. Cellular metabolism generates numerous by-products, many rich in nitrogen, that require elimination from the bloodstream...

 flow from the kidney

Kidney

The kidneys, organs with several functions, serve essential regulatory roles in most animals, including vertebrates and some invertebrates. They are essential in the urinary system and also serve homeostatic functions such as the regulation of electrolytes, maintenance of acid–base balance, and...

. The length of the stents used in adult patients varies between 24 to 30 cm. Additionally, stents come in differing diameters or gauges, to fit different size ureters. The stent is usually inserted with the aid of a cystoscope. One or both ends of the stent may be coiled to prevent it from moving out of place, this is called a JJ stent, double J stent or pig-tail stent.

Stent Placement

Ureteral stents are used to ensure the patency of a ureter

Ureter

In human anatomy, the ureters are muscular tubes that propel urine from the kidneys to the urinary bladder. In the adult, the ureters are usually long and ~3-4 mm in diameter....

, which may be compromised, for example, by a kidney stone

Kidney stone

A kidney stone, also known as a renal calculus is a solid concretion or crystal aggregation formed in the kidneys from dietary minerals in the urine...

. This method is sometimes used as a temporary measure, to prevent damage to a blocked kidney, until a procedure to remove the stone can be performed. Indwelling times of 12 months or longer are indicated to hold ureters open, which are compressed by tumors in the neighbourhood of the ureter or by tumors of the ureter itself. In many cases these tumors are inoperable and the stents are used to ensure drainage of urine through the ureter. If drainage is compromised for longer periods, the kidney can be damaged.

Stents may also be placed in a ureter that has been irritated or scratched during a ureteroscopy

Ureteroscopy

Ureteroscopy is an examination of the upper urinary tract, usually performed with an endoscope that is passed through the urethra, bladder, and then directly into the ureter...

 procedure that involves the removal of a stone, sometimes referred to as a 'basket grab procedure'. Stents placed for this reason are normally left in place for about a week. These stents ensure that the ureter does not spasm and collapse after the trauma of the procedure.

Side Effects and Complications

The main complications with ureteral stents are dislocation, infection

Infection

An infection is the colonization of a host organism by parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease...

 and blockage by encrustation. Recently stents with coatings, such as heparin

Heparin

Heparin , also known as unfractionated heparin, a highly sulfated glycosaminoglycan, is widely used as an injectable anticoagulant, and has the highest negative charge density of any known biological molecule...

, were approved to reduce infection and encrustation to reduce the number of stent exchanges.

Other complications can include increased urgency and frequency of urination, blood in the urine, leakage of urine, pain in the kidney, bladder, or groin, and pain in the kidneys during, and for a short time after urination. These effects are generally temporary and disappear with the removal of the stent.

Stents often have a thread, used for removal, that passes through the urethra

Urethra

In anatomy, the urethra is a tube that connects the urinary bladder to the genitals for the removal of fluids out of the body. In males, the urethra travels through the penis, and carries semen as well as urine...

 and remains outside the body. This thread may cause irritation of the urethra. This may be increased for patients who were born with Hypospadias

Hypospadias

Hypospadias is a birth defect of the urethra in the male that involves an abnormally placed urinary meatus...

 or other conditions that required a similar corrective surgery. Care must be taken to ensure that the thread is not caught or pulled, which may dislodge the stent.

While the stent is in place, patients may carry on with most normal activities, however the stent may cause some discomfort during strenuous physical activity. Work and other daily activities may continue as normal. Sexual activity is also possible with a stent, but stents with a thread may significantly hinder sex. The stent also can rest on the prostate gland in men and with ejaculation/orgasm the prostate may have movement that is discomforting to the patient and similar to severe cramping or irritation. One should approach sex differently with a stent exercising caution and certainly using some type of protection to prevent transmission of some sexually transmitted diseases.

Removal

Stents with a thread may be removed in a matter of a few seconds by pulling on the thread. This is often done by a nurse, but can be done by the patient. When removing the stent, constant, steady force should be applied, to avoid starting and stopping. Something should also be placed below the patient to catch any urine that leaks during removal. Stents without a thread are removed by a doctor using a cystoscope.

Additional reading

• Ureteral Stent

1. Ureteral stents- Materials; Endourology update: Mardis HK, Kroeger RM: Urological Clinics of North America, 1988, Vol. 15, No.3, 471-479.
2. Ureteral stents – indications, variations and complications: Saltzman B: Endourology update : Urological Clinics of North America, 1988, Vol.15, No.3, 481-491.
3. Self retained internal ureteral stents: Use and complications: Mardis HK: AUA update series, 1997, Lesson 29, Volume XVI.
4. External urinary diversion: pathologic circumstances and available technology. Macaluso JN Jr. J Endourol. 1993 Apr;7(2):131-6. PMID: 8518825
5. Having a Ureteric Stent - What to Expect and How to Manage. Authors: Mr. H. B. Joshi (Specialist Registrar in Urology, Cambridge. Formerly Research Registrar at Bristol Urological Institute), N. Newns (Staff Nurse), Mr. F. X. Keeley Jr. (Consultant Urologist), Mr. A. G. Timoney (Consultant Urologist), Bristol Urological Institute, Southmead Hospital, Westbury-on-trym, Bristol BS10 5NB