Urinary tract obstruction

Last updated: December 7, 2023

Summarytoggle arrow icon

Urinary tract obstruction (UTO) is a mechanical or functional blockage that inhibits the outflow of urine. Any part of the urinary tract can be affected by UTO. The etiology of UTO may be congenital, neoplastic, or inflammatory; additional etiologies include certain neurological conditions and stones. A UTO may be partial or complete and unilateral or bilateral. The clinical features of UTO depend on the etiology, location, degree, and duration of obstruction. Patients with chronic UTO are often asymptomatic until they develop complications (e.g., urinary tract infections, renal failure). The initial evaluation of UTO includes ultrasound and laboratory studies (CBC, BMP, urinalysis). In some cases, further urinary tract imaging may be carried out to provide additional diagnostic information. Treatment depends on the site and degree of obstruction and the presence of infection. Complete UTO is a medical emergency and must be treated promptly with bladder catheterization, ureteral stenting, or percutaneous nephrostomy.

Etiologytoggle arrow icon

Upper urinary tract obstruction (supravesicular urinary tract obstruction) [1][2]

Renal obstruction

Ureteral obstruction

Lower urinary tract obstruction (bladder outlet obstruction) [1][2]

Bladder obstruction

Urethral obstruction

The most common etiology of UTO is dependent on age: congenital anomalies (e.g., posterior urethral valves) in children, nephrolithiasis in young adults, and prostatic enlargement (BPH and prostate cancer) in older adults. [1]

Clinical featurestoggle arrow icon


  • Clinical features depend on the etiology, location, degree, and duration of obstruction.
  • Features range from oliguria or anuria to incidentally diagnosed asymptomatic hydronephrosis.
Clinical features of urinary tract obstruction
Upper (supravesical) UTO Lower (infravesical) UTO
Acute obstruction
Chronic obstruction

Urinary obstruction may be partial or complete and unilateral or bilateral (in the case of upper UTO).

Patients with a UTO may be asymptomatic. It may be an incidental finding on ultrasound or become apparent through a rise in creatinine levels seen on routine blood work.

Hydronephrosis [11]

Always consider gynecologic malignancies (e.g., cervical, uterine, ovarian) in nonpregnant women with new-onset hydronephrosis.

Subtypes and variantstoggle arrow icon

Urethral stricture

Ureteropelvic junction obstruction [14][15]

Diagnosticstoggle arrow icon


Do not delay relieving pressure on the urinary tract during the diagnostic workup. Perform bladder catheterization or consult urology for upper urinary tract interventions as indicated. [11]

Consider screening patients with unexplained AKI for upper UTO using renal and urinary tract ultrasound.

Laboratory studies [1][16]

Consider further studies (e.g., urine and blood cultures for suspected UTI) based on initial findings.

Imaging [1][18]

Routine studies

Typical findings include hydronephrosis, hydroureter, and perinephric fluid.

Specialized studies

Consider the following studies under specialist guidance for further evaluation of specific suspected causes or if initial testing is inconclusive. See “Imaging techniques in urology” for details.

Treatmenttoggle arrow icon

UTO accompanied by acute kidney injury, signs of sepsis, refractory pain, dehydration (due to nausea and vomiting), or anuria (suggesting complete UTO) is a medical emergency. Prompt drainage of the urinary tract is indicated to prevent severe complications.

Management of upper UTO [11][18][19]

Nephroureterectomy may be performed if the involved kidney is nonfunctional. [21]

Management of lower UTO [22][23]

Supportive care for urinary tract obstruction

Treatment of the underlying cause

See “Etiology of urinary tract obstruction” and the respective articles (e.g., benign prostatic hyperplasia) for details. See “Treatment of urinary retention” for the management of functional obstruction.

Disposition [23]

  • Consider admission for patients with neurological deficits, refractory pain, upper UTO, or complications of UTO (e.g., urosepsis, AKI).
  • Stable patients with lower UTO: After bladder decompression, consider discharge with an indwelling catheter for outpatient urology follow-up.

Complicationstoggle arrow icon

UTO increases the risk of urolithiasis and UTIs progressing to urosepsis.

We list the most important complications. The selection is not exhaustive.

Referencestoggle arrow icon

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  13. Rourke K, Hickle J. The Clinical Spectrum of the Presenting Signs and Symptoms of Anterior Urethral Stricture: Detailed Analysis of a Single Institutional Cohort. Urology. 2012; 79 (5): p.1163-1167.doi: 10.1016/j.urology.2012.01.044 . | Open in Read by QxMD
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