Nephroureteral stent

A nephroureteral stent, often called an NU stent or NUS, combines two things in one tube. Like a nephrostomy tube, it enters through the skin of your back into the kidney. Like a ureteral stent, it continues down the ureter, the tube that carries urine to the bladder, and ends in a small curl inside the bladder.

The tube has side holes along its length. Urine can drain in two directions: out through the back into a bag, or down through the tube into the bladder so you pee normally. Which way it goes depends on whether the outside end is open or capped.

What we see

An NU stent is often a bridge. It is useful when we want the comfort of internal drainage but also want an easy way back if things do not go as planned.

Our interventional urology page explains how these three tubes work together along one treatment path.

1. 1
   Getting ready

   You lie on your stomach. You receive moderate sedation through your IV, and monitors track your heart, blood pressure and oxygen.

2. 2
   Entering the kidney

   We numb the skin and use your existing nephrostomy track, or make a new small needle stick into the kidney under ultrasound and X-ray. Contrast dye shows the ureter and the blockage.

3. 3
   Placing the stent

   A guidewire is steered down the ureter, through the narrow spot and into the bladder. The NU stent slides over the wire so its tip curls in the bladder and its side holes sit along the ureter and kidney.

4. 4
   Securing and connecting

   The outside end is secured to your skin, covered with a dressing and usually connected to a bag at first.

The procedure usually takes 30 to 60 minutes. You rest for about an hour afterward and most people go home the same day.

At first, the tube usually drains into a bag for a day or more while any bleeding clears. Then we ask you to cap it, which means closing the outside end so urine flows down into the bladder. This is called a capping trial.

1. First day
   Tube open to a bag. Rest, no driving after sedation. Pink urine is normal.
2. Day 1 to 3
   If we have told you to, cap the tube. Watch for side pain, fever or leaking around the tube.
3. If capping goes well
   Keep it capped. Change the dressing daily and shower normally. No bag needed.
4. If capping causes problems
   Uncap it and reconnect the bag, then call us. This takes the pressure off right away.
5. Every 8 to 12 weeks
   Short visit to change the tube over a wire, or to convert or remove it.

Care of the skin is the same as for a nephrostomy tube: wash your hands, change the dressing daily or when wet, keep the tube taped so it cannot be pulled, and do not soak in a bath or pool. See managing your drain and home supplies.

The NU stent is rarely the last step. Once your kidney drains well with the tube capped, we can often swap it for a fully internal ureteral stent, so nothing exits your back. If the blockage has been fixed, we can remove it after a dye check shows urine flows freely. If internal drainage does not work, we can change it back to a simple nephrostomy tube.

I like the NU stent because it lets us test internal drainage without burning any bridges. If you do well capped for a week or two, I feel confident moving you to a fully internal stent. If you don't, you just open the cap, and we have learned something useful without another urgent procedure.

Fabio Komlos, MD, interventional radiologist · About Dr. Fabio Komlos