What Is a Kidney Stent and When Is It Needed?

A kidney stent is a thin tube a doctor places inside the ureter, the narrow tube that carries urine from each kidney down to the bladder. Its whole job is to keep urine draining past a blockage and to prevent the damage a backed-up kidney can suffer.¹ Most stents are temporary, and many people notice them every day until they come out, which is why doctors now weigh carefully whether one is needed at all.

What a Kidney Stent Looks Like and How It Works

In the common type, each end curls like a pig’s tail. One curl sits in the kidney and the other in the bladder, which anchors the tube against sliding up or down.² Early stents with a single loop tended to slip out of position, which is why the two-curl design became standard.³

Each kidney drains through its own ureter, so a stent usually serves just one side. The tube runs from the kidney’s collecting area down the full length of the ureter, several inches in all, and the lower curl rests inside the bladder. That placement matters later, because it explains many of the symptoms. Some stents also have a thin string trailing out through the urethra to make removal easy.

Urine flows both through the stent’s hollow center and along its outside.⁴ Small side holes along the tube let urine enter and leave, which helps most when the ureter is badly narrowed.⁵ Wider stents tend to carry more urine.⁶

Most stents are soft plastic such as polyurethane or silicone, and silicone’s softness was thought to make it more comfortable.⁷ Soft stents may not stay open when a tumor presses on the ureter from outside, so metal stents exist for those cases.⁸

Putting one in usually doesn’t need a skin cut. The doctor passes a camera scope through the urethra and bladder, sends a thin guide wire up to the kidney first, then slides the stent over the wire. X-ray imaging confirms the top curl sits in the kidney. Sometimes this is done with local numbing as an outpatient, though general anesthesia is common.

When a Stent Is Needed for a Blocked Kidney

A stone stuck in the ureter can back urine up into the kidney, which then swells. Drainage with a stent or tube is needed when the blockage causes persistent pain, high fever, or signs that waste is building up in the blood.⁹ A fever with a blocked kidney is treated as urgent, because infected urine trapped behind a stone can spread into the blood. Pain that painkillers don’t control, or vomiting that keeps you from holding down fluids, also means a blocked kidney needs care the same day.

Doctors often drain a blocked, infected kidney before dealing with the stone. Antibiotics alone aren’t enough, because the medicine has a hard time clearing infected urine trapped behind a blockage. Draining first and treating the stone later is safer than operating while the urine is infected.

A stent is a bridge, not a cure. It opens a channel so urine can drain, but the stone usually stays where it is until it passes or is treated. A separate procedure to break or remove it is often planned for later, after the infection or swelling has settled.

Stents also protect healing. After scope procedures to open a narrowed ureter, a stent is often left about a month so the ureter heals open.¹⁰ When a ureter is surgically repaired or reconnected, the repair is done over a stent to let it heal and reduce leaks.¹¹ Ureters accidentally injured during pelvic surgery can be treated with a stent left about 5 weeks.¹²

Long-term blockage is a different problem. Cancer pressing on a ureter can block it for months, and about half of stents placed for this fail.¹³ Stiffer metal stents resist that pressure better and can keep working longer, about 5 months versus under 2 for plastic in one group of cancer patients.¹⁴ Self-expanding metal stents are also an option for narrowed ureters in people who can’t have reconstructive surgery.¹⁵

Do You Need a Stent After Stone Surgery

Ureteroscopy means removing a stone with a thin scope passed up the ureter. After an uncomplicated one, people with stents have about twice the burning and urgency of those without.¹⁶ Stents didn’t improve stone clearance, infection rates, painkiller needs, or later scarring.¹⁷ In one trial, people without stents had fewer problems and fewer return hospital visits.¹⁸

Stents still help after complicated cases. They are commonly placed when the ureter was injured or looks raw or swollen after the scope passes through it. They are also used when the stone was large, when fragments were left behind, or when the ureter was too narrow for the scope to move through easily. Infection before surgery is another reason, since swelling and debris can block drainage afterward. So is having only one kidney, or a kidney that already works poorly, because the surgeon won’t want to risk a blockage.

Before surgery, ask whether your case counts as uncomplicated and whether a stent is planned. If one is, ask why: swelling, injury, leftover fragments, or a large stone. Ask how long it will stay and how it comes out. Many urologists still stent after complicated cases, and that can be the right call.

What Living With a Stent Feels Like

The lower curl rubs the bladder lining, causing urgency and frequency.¹⁹ Urine can also travel back up the stent to the kidney when you urinate, raising pressure there and causing flank pain.²⁰

In one trial, flank pain, burning, urgency, frequency, blood in urine and lower belly pain were all higher with a stent than without.²¹ Pink or light red urine, especially after activity, is common. In pregnant women, about 1 in 6 reported stent irritation.²²

Most people can work and do light activity. Strenuous exercise may increase bleeding and discomfort. Drinking enough water keeps urine dilute, but drinking more than that won’t remove the stent pain. Sex is often uncomfortable, so ask your doctor what’s safe.

A change in pain deserves attention. Pain that is new, much worse, or in a different place from what you have had can mean the stent has shifted or the kidney is blocked. Fever with chills, not being able to pass urine, or clots that block the flow need prompt same-day care.

Medicines That Ease Stent Discomfort

Tamsulosin, a drug that relaxes muscle in the urinary tract, eased urinary symptoms and cut painkiller use in one trial.²³ Mirabegron, an overactive-bladder drug, lowered painkiller need.²⁴ In another trial mirabegron beat solifenacin on urinary, work and sexual scores, making it an alternative if others fail.²⁵ Tamsulosin plus solifenacin together improved symptoms more than either alone in one trial.²⁶

Tamsulosin relaxes the muscle in the ureter and the bladder outlet, while solifenacin and mirabegron calm an overactive bladder. Since they work in different ways, a doctor may add a second medicine if the first leaves you uncomfortable, or switch types if one causes side effects.

Ask for a prescription at the time the stent is placed. Tamsulosin can cause dizziness on standing. These medicines help but rarely remove discomfort entirely, so you may still need over-the-counter pain relief; ask which kind is safe for your kidneys.

Risks and Why You Must Not Forget Your Stent

Bacteria settle on virtually every stent left in place, forming a film.²⁷ Minerals in urine can then build up on it as a crust, especially with infection.²⁸ Risk rises with long dwell time, past stones, infection, chemotherapy, and kidney failure.²⁹ A stent forgotten for years can crust, break apart and need several surgeries to remove.³⁰ A crusted stent can also stop draining, so the kidney may become blocked or infected again.

Stents rarely move, but the wrong length or position raises the risk.³¹ A moved stent may cause no symptoms or new pain.³²

To make sure yours comes out, write the removal date down when it is placed. If no appointment arrives, call the urology office. Keep a card or note saying you have a stent, and ask how long your stent type is approved to stay.

How a Stent Is Removed

After stone surgery, stents are often removed about 10 days later.³³ Removal by string hurt much less than by scope, especially for men.³⁴ Magnetic stents can be pulled with a catheter-like device in about 10 minutes, less painful than scope removal.³⁵

Scope removal is often done awake with numbing gel. The pull itself takes seconds. A brief cramp or burning afterward is common, and some people get a short flare of flank pain hours later.

If you have a string stent and your doctor has you remove it at home, they will tell you when and how. Pull gently and steadily. Stop and call if it resists. Afterward, check that the stent came out whole.

Alternatives to a Stent

A nephrostomy tube drains the kidney directly through the skin of the back into a bag.³⁶ For stone blockages, it may be better tolerated, with fewer urinary symptoms.³⁷ It brings bleeding risk, tube slipping, and an external bag.³⁸ It’s preferred in advanced cancer, unstable patients, or when a stent can’t be passed.³⁹ Emergency teams choose based on how sick you are and what’s available, so ask which is planned and why.

Living with a drainage tube through the back means emptying and carrying a bag, which affects clothing, sleep position, and bathing. The dressing where the tube enters the skin needs regular changing, and your care team will show you how. The tube can be pulled or dislodged, so it is secured to the skin and movement needs care. If it stops draining or falls out, you need to be seen promptly, since the kidney may back up again.

Stents in Pregnancy and in Children

Stents for stones in pregnancy relieve pain and obstruction without harm to the pregnancy.⁴⁰ Pregnancy urine crusts stents faster, so they’re usually changed every 4 to 6 weeks.⁴¹ Minor complications are common but serious ones are under 1 in 100.⁴²

The growing uterus and pregnancy hormones can slow urine flow and make a kidney more likely to back up. Doctors avoid X-ray when possible and often use ultrasound to find a blockage. Surgery to remove the stone is often delayed until after delivery, so the stent holds things steady meanwhile. Pain, fever, or a blocked kidney is treated seriously, since infection can affect both mother and baby.

Placement often uses local numbing. Expect repeat procedures until after birth, and report fever promptly.

In children with blocked kidneys from birth, stents alone resolved swelling in about 3 in 4 cases.⁴³ Success was highest under age 5.⁴⁴ Some children later need reconstructive surgery.⁴⁵

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