A ureteral stricture is an abnormal narrowing in the ureter, the muscular tube that carries urine from the kidney to the bladder. This constriction impedes the normal passage of urine, creating a blockage that can lead to significant health complications.
Defining the Ureter and the Stricture
The ureters are two narrow tubes, typically about 10 to 12 inches long, connecting the renal pelvis of each kidney to the urinary bladder. Their primary function is to transport urine unidirectionally via rhythmic, wave-like contractions called peristalsis. This continuous, active transport system is essential for maintaining healthy pressure within the kidney.
A ureteral stricture occurs when scar tissue forms within the ureter’s lumen, physically constricting the tube and creating an obstruction. This scarring results from inflammation or injury, causing the inner diameter of the ureter to decrease significantly.
The resulting obstruction causes urine to back up and collect in the kidney’s collecting system, a condition known as hydronephrosis. Hydronephrosis is the swelling and stretching of the kidney due to this fluid buildup. Untreated, this increased pressure can lead to permanent kidney damage or the complete loss of kidney function over time.
Primary Causes of Ureteral Strictures
Stricture formation is primarily a response to tissue damage that triggers a healing process resulting in scar tissue and narrowing. One common category of causes is iatrogenic, meaning the stricture arises as a complication of a prior medical procedure or surgery. Surgical interventions in the pelvic or abdominal region, such as a hysterectomy or ureteroscopy for kidney stone removal, can inadvertently cause trauma or disrupt the ureter’s blood supply, leading to scarring.
Another frequent cause is urolithiasis, specifically when a kidney stone becomes severely impacted in the ureter. The direct trauma from a lodged stone or the instrumentation used during stone treatment can injure the ureteral lining, leading to scar formation.
Radiation exposure, particularly in patients undergoing pelvic radiation therapy for cancers such as cervical, prostate, or rectal cancer, can also lead to stricture formation. The radiation damages the ureteral tissue, causing chronic inflammation and fibrosis that develops gradually over months or even years. Less common causes include external trauma or chronic inflammation from conditions like retroperitoneal fibrosis. Some strictures are also congenital, meaning the narrowing is present from birth, often occurring at the ureteropelvic junction.
Recognizable Symptoms and Related Effects
Symptoms of a ureteral stricture stem from the obstruction of urine flow and pressure buildup in the kidney. Patients may experience flank pain or discomfort in the upper abdomen, localized to the affected side. This pain is often intermittent and may worsen after consuming large amounts of fluid, which exacerbates the blockage.
Impaired drainage makes the affected kidney susceptible to infection, leading to recurrent urinary tract infections (UTIs). If the infection reaches the kidney, symptoms can include fever, chills, and vomiting. Visible blood in the urine, known as hematuria, may also occur due to physical damage.
A significant concern is that a slowly developing stricture may be entirely asymptomatic, or “silent,” even as it causes severe obstruction. However, when left untreated, the chronic hydronephrosis places continuous stress on the organ’s functional units. This prolonged, elevated pressure can ultimately lead to irreversible kidney damage, potentially compromising the organ’s ability to filter waste and maintain fluid balance.
Diagnosis and Treatment Pathways
Diagnosing a ureteral stricture requires a combination of imaging and functional tests to pinpoint the location and extent of the narrowing. Initial steps involve non-invasive imaging, such as a computed tomography (CT) scan with contrast dye or an ultrasound, which can reveal the presence of hydronephrosis and sometimes the exact point of obstruction. Specialized tests, like a nuclear medicine renal scan, are also performed to evaluate the degree of obstruction and determine how well the kidney is currently functioning.
More detailed diagnostic procedures include a retrograde pyelogram or ureteroscopy. During these procedures, a thin scope is passed through the bladder into the ureter, allowing the physician to visualize the stricture directly. This information is used to determine the most appropriate treatment strategy.
Treatment is determined by the stricture’s length, location, and underlying cause, ranging from endoscopic procedures to surgical reconstruction. For short strictures, minimally invasive endoscopic options are often attempted first. These involve passing instruments to perform balloon dilation or endoureterotomy, which cuts the scar tissue to widen the passage.
For longer or recurrent strictures, definitive surgical repair is typically required, often using robotic or laparoscopic techniques. Common procedures include ureteroureterostomy, where the narrowed segment is removed and the healthy ends are reconnected. Distal strictures, closer to the bladder, may be repaired with a ureteral reimplantation, sometimes combined with a psoas hitch or Boari flap procedure.