A ureteral stent (pronounced you-REE-ter-ul), or ureteric stent, is a thin tube inserted into the

ureter The ureters are tubes made of smooth muscle that propel urine from the kidneys to the urinary bladder. In a human adult, the ureters are usually long and around in diameter. The ureter is lined by urothelial cells, a type of transitional epit ...

to prevent or treat obstruction of the

urine Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excretion, excreted from the body through the urethra. Cel ...

flow from the

kidney The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; blood ...

. The length of the stents used in adult patients varies between 24 and 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 Cystoscopy is endoscopy of the urinary bladder via the urethra. It is carried out with a cystoscope. The urethra is the tube that carries urine from the bladder to the outside of the body. The cystoscope has lenses like a telescope or microscope ...

. 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 openness of a

, which may be compromised, for example, by a

kidney stone Kidney stone disease, also known as nephrolithiasis or urolithiasis, is a crystallopathy where a solid piece of material (kidney stone) develops in the urinary tract. Kidney stones typically form in the kidney and leave the body in the urine s ...

or a procedure. 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 is an examination of the upper urinary tract, usually performed with a ureteroscope that is passed through the urethra and the bladder, and then directly into the ureter. The procedure is useful in the diagnosis and treatment of diso ...

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.

Contraindications

A technical drawback of ''ureteric stents'' is that they by-pass the 1-way valve at the entrance of the ureter into the bladder, the normal vesicoureteral (ureteral-bladder) junction. The function of this valve is to prevent backflow of urine from the bladder to the kidney (

vesicoureteral reflux Vesicoureteral reflux (VUR), also known as vesicoureteric reflux, is a condition in which urine flows retrograde, or backward, from the bladder into one or both ureters and then to the renal calyx or kidneys. Urine normally travels in one directi ...

). A ''ureteric stent'' thus leads to the loss of the valve function thereby opening up the ureter to backflow. The main risk of such a backflow is the spreading of

urinary tract infection A urinary tract infection (UTI) is an infection that affects part of the urinary tract. When it affects the lower urinary tract it is known as a bladder infection (cystitis) and when it affects the upper urinary tract it is known as a kidney ...

s up into the

renal pelvis The renal pelvis or pelvis of the kidney is the funnel-like dilated part of the ureter in the kidney. It is formed by the covnvergence of the major calyces, acting as a funnel for urine flowing from the major calyces to the ureter. It has a mucous ...

, which can then lead to an inflammation of the kidney (

pyelonephritis Pyelonephritis is inflammation of the kidney, typically due to a bacterial infection. Symptoms most often include fever and flank tenderness. Other symptoms may include nausea, burning with urination, and frequent urination. Complications may ...

). Such a condition, in turn, implies the risk of a life-threatening

urosepsis Pyelonephritis is inflammation of the kidney, typically due to a bacterial infection. Symptoms most often include fever and flank tenderness. Other symptoms may include nausea, burning with urination, and frequent urination. Complications may i ...

(blood poisoning). ''Ureteric stenting'' is therefore no option, if the patient shows conditions which favor a backflow of urine from the bladder to the kidney or if a urinary tract infection is present or suspected. Major such conditions are: * Actual or suspected urinary tract infection * Obstruction of urine flow below the bladder (prostate enlargement by

benign prostatic hyperplasia Benign prostatic hyperplasia (BPH), also called prostate enlargement, is a noncancerous increase in size of the prostate gland. Symptoms may include frequent urination, trouble starting to urinate, weak stream, inability to urinate, or loss o ...

; narrowing of the urethra by

urethral stricture A urethral stricture is a narrowing of the urethra, the tube connected to the bladder that allows the passing of urine. The narrowing reduces the flow of urine and makes it more difficult or even painful to empty the bladder. Urethral stricture is ...

): risk of backflow due to increased pressure in the bladder *

Overactive bladder Overactive bladder (OAB) is a condition where there is a frequent feeling of needing to urinate to a degree that it negatively affects a person's life. The frequent need to urinate may occur during the day, at night, or both. If there is loss ...

: risk of backflow due to periods of increased pressure in the bladder *

Urinary incontinence Urinary incontinence (UI), also known as involuntary urination, is any uncontrolled leakage of urine. It is a common and distressing problem, which may have a large impact on quality of life. It has been identified as an important issue in geria ...

: temporarily increased pressure in the bladder

Side effects and complications

The main complications with ureteral stents are dislocation,

infection An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable dise ...

and blockage by encrustation. Recently stents with coatings, such as heparin, 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. Drugs used for the treatment of OAB (over active bladder) are sometimes given to reduce or eliminate the increased urgency and frequency of urination caused by the presence of the stent. Stents often have a thread, used for removal, that passes through the

urethra The urethra (from Greek οὐρήθρα – ''ourḗthrā'') is a tube that connects the urinary bladder to the urinary meatus for the removal of urine from the body of both females and males. In human females and other primates, the urethra con ...

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 is a common variation in fetal development of the penis in which the urethra does not open from its usual location in the head of the penis. It is the second-most common birth abnormality of the male reproductive system, affecting abou ...

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, similar to severe cramping or irritation. One should approach sex differently with a stent, exercising caution.

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

. The stent is removed by cystoscopy, an outpatient procedure. Cystoscopy involves placement of a small flexible tube through the urethra (the hole where urine exits the body). The procedure, which usually takes only a few minutes and causes little discomfort, is performed in an outpatient clinic or ambulatory surgery centre. Most patients tolerate having the stent removed using only a topical anesthetic placed in the urethra. Immediately before the procedure, sterile lubrication containing local anesthetic (lidocaine) is instilled into the urethra. Since no intravenous line is inserted and there is no anesthesia, the patient does not have to be accompanied by anyone else and they can eat normally before and after the procedure. A ureteric stent may also be retrieved without the use of a cystoscope by means of a magnetic removal system. The stent inserted has a small rare earth magnet attached to its bladder end which dangles freely within the bladder. When the stent needs to be removed a small catheter with a similar magnet is inserted into the bladder and the two magnets connect and the catheter and stent can be simply removed. This eliminates the need for a costly and invasive cystoscopy in both adults and children. Peer reviewed papers show that more than 98% of stents can be retrieved with a magnet in adults, paediatric and kidney transplant patients. Avoidance of a general anesthetic in children is very significant and also results in enormous cost-savings because the procedure no longer need to be done in the operating room. Magnetic retrieval of the stent does not require a urologist and can be done by primary care physicians, nurse practitioners and nurses.

References

* J Urol Vol 168, 2023–2023, Nov 2002 * AUA University Series, abstract PD37-11

Stent placement

Contraindications

Side effects and complications

Removal

References

Further reading