A ureteral stricture is a narrowing of the ureter, one of the two thin tubes that carry urine from your kidneys down to your bladder. When scar tissue or inflammation narrows this passageway, urine can’t drain properly, and the backup can damage your kidney surprisingly fast. About 75% of all ureteral strictures are caused by prior pelvic surgery or radiation treatment, making this largely a complication of other medical procedures rather than something that develops on its own.
What Causes a Ureteral Stricture
The most common cause is surgical injury to the ureter during a pelvic operation. This can happen through direct damage (the ureter is accidentally cut, sutured, crushed, or burned by a cautery tool) or indirect damage from disrupting the blood supply to that section of the tube. Ureteroscopy, a procedure used to treat kidney stones, is another frequent culprit, particularly when the stone is large or impacted.
Radiation therapy for pelvic cancers is the second major cause. Unlike surgical injuries that show up right away, radiation-related strictures often take years to develop. The radiation gradually damages the tissue lining the ureter, and scar tissue slowly builds until the tube narrows enough to block flow. The risk depends on the radiation dose and technique used.
Less common causes include chronic inflammatory conditions like Crohn’s disease, prior kidney stone damage, infections, and (rarely) tumors pressing on or growing into the ureter wall.
Symptoms to Watch For
The tricky thing about ureteral strictures is that they can be completely silent. In one study of 30 patients, seven had no symptoms at all, even as their kidneys were being damaged by the blockage. One patient had such severe undetected obstruction that they eventually needed dialysis for kidney failure.
When symptoms do appear, the most common ones are:
- Flank pain: a dull ache or pressure between your upper belly and mid-back, on the side of the affected ureter
- Recurring urinary tract infections: urine that can’t drain properly becomes a breeding ground for bacteria
- Hydronephrosis: in more severe cases, urine backs up enough to cause visible swelling of the kidney, which may show up as worsening pain or be found on imaging
Because symptoms can be absent or vague, people who’ve had complicated ureteroscopy or pelvic surgery should have follow-up imaging to catch a stricture before kidney damage sets in.
How Ureteral Strictures Are Diagnosed
Diagnosis typically starts with imaging. A CT scan of the urinary tract can reveal a swollen kidney or a dilated ureter above the narrowed segment. Ultrasound is often used as a first-line tool because it’s quick and radiation-free, and it can detect hydronephrosis easily.
To see the stricture itself in detail, doctors use retrograde pyelography: a contrast dye is injected through a small scope placed in the bladder and up into the ureter, then X-rays are taken. This shows exactly where the narrowing is, how long it is, and how severe it is. A small flexible camera (ureteroscopy) can also be passed into the ureter for a direct look. The stricture’s length, location, and severity all determine which treatment makes sense.
Treatment Options
Treatment depends on how long the narrowed segment is, where it sits along the ureter, and whether it’s a first-time problem or a recurrence.
Stenting and Balloon Dilation
For mild or short strictures, the least invasive approach is placing a ureteral stent (a thin flexible tube) to hold the ureter open, sometimes after inflating a small balloon to widen the narrowed area. The one-year success rate for balloon dilation alone in the lower ureter is roughly 78%, and combining it with a laser incision of the scar tissue bumps that to about 87%. For upper ureteral strictures, the numbers are lower, around 73% at one year for first-time treatment and only about 53% when treating a recurrence after a prior repair.
A stent typically stays in place for a few days to four weeks. In cases involving a very narrow ureter, it may remain for up to three months. While the stent is in, you can do normal daily activities like walking, light housework, and gentle swimming, but you should avoid heavy lifting and strenuous sports. Common side effects include irritation or a burning sensation when urinating, and small amounts of blood in the urine, especially after physical activity.
Surgical Repair
When the stricture is too long, too severe, or has come back after a less invasive procedure, surgery offers a more durable fix. The specific technique depends on which part of the ureter is affected.
For strictures in the lower ureter (near the bladder), the most common approach is ureteral reimplantation: the scarred section is removed and the healthy end is reconnected directly to the bladder. A bladder flap technique can bridge a slightly longer gap by creating a tube of bladder tissue to reach the remaining ureter.
Short strictures in the mid or upper ureter can sometimes be cut out and the two healthy ends stitched back together. For very long strictures, or those spanning most of the ureter’s length (over 20 cm), surgeons may use a segment of small intestine to replace the damaged ureter entirely. This intestinal substitution can be combined with bladder flap techniques to minimize how much bowel tissue is needed.
In rare, complex situations where radiation or inflammatory disease makes all of these options difficult, a kidney autotransplant is possible. The kidney is moved from its normal position and reconnected to blood vessels and the bladder lower in the pelvis, bypassing the damaged ureter altogether. Robotic-assisted versions of several of these surgeries are increasingly available, offering smaller incisions and potentially shorter recovery.
What Happens If a Stricture Goes Untreated
Ureteral strictures are a significant cause of preventable kidney damage. The obstruction raises pressure inside the kidney, and over time this destroys functional tissue. In some cases the timeline is alarmingly short. One documented case involved a patient who had a normal-looking ureter on imaging after a stent was removed, only to develop a stricture so rapidly that the kidney became completely nonfunctional within three months and had to be surgically removed.
Because kidney damage from obstruction can be irreversible, and because many strictures cause no pain, imaging follow-up is critical after any pelvic surgery or ureteroscopy that was complicated by injury, perforation, or a difficult stone extraction. Early detection, before kidney function drops, gives you the widest range of treatment options and the best chance of keeping the kidney healthy long-term.