Merck Manual

Please confirm that you are not located inside the Russian Federation

honeypot link
Quick Facts

Urinary Tract Obstruction


The Manual's Editorial Staff

Last full review/revision Apr 2020| Content last modified Apr 2020
Click here for the Professional Version
Get the full details
Topic Resources

What is urinary tract obstruction?

Your urinary tract is the path that urine follows from your kidneys to your bladder and out of your body. Obstruction means your urinary tract is blocked somewhere along that path.

  • Urinary tract obstruction can happen in your kidneys, the tubes that connect each kidney to your bladder (ureters), your bladder, or the tube your pee comes out (urethra)

  • Many things can cause urinary tract obstruction, including scar tissue, tumors, or kidney stones

  • A urinary tract obstruction can cause pain and infection

  • If it goes on long enough, a urinary tract obstruction can cause kidney damage

  • Doctors remove the blockage with medicine or surgery depending on what caused it

Distended Kidney

In hydronephrosis, the kidney is swollen (distended) because the flow of urine is obstructed. Urine backs up behind the obstruction and remains in the kidney’s small tubes and central collecting area (renal pelvis).

Distended Kidney

What causes urinary tract obstruction?

Common causes of urinary tract obstruction include:

Other causes of urinary tract obstruction include:

  • Scar tissue due to radiation therapy, surgery, or procedures

  • Cancerous or noncancerous (benign) growths

  • Blood clots

What are the symptoms of urinary tract obstruction?

Symptoms of urinary tract obstruction depend on where the obstruction is, how quickly it happens, and how severe the blockage is.

Symptoms include:

  • Severe pain on one side of your belly or one side of your back below your ribs

  • Decreased urine flow

  • Urinating more often at night

  • Nausea and throwing up

You may have a fever and pus or blood in your urine, if the obstruction causes a urinary tract infection.

How can doctors tell if I have urinary tract obstruction?

Doctors suspect a urinary tract obstruction from your symptoms. To know for sure they usually do:

  • Ultrasound or CT scan

If that shows obstruction but not the cause, then doctors may:

  • Do voiding cystourethrography (VCUG), a test where doctors inject a dye into your bladder using a catheter and take an x-ray to see the flow of your urine

  • Use a flexible viewing tube to examine your urethra, prostate, and bladder

Doctors may also do blood tests to look for signs of kidney damage and urine tests to look for a urinary tract infection.

How do doctors treat urinary tract obstruction?

Doctors will remove the blockage from your urinary tract.

  • If you have a kidney stone, doctors usually wait for it to pass on its own

  • If a kidney stone doesn't pass on its own, doctors try to break it up using powerful sound waves (shock wave lithotripsy) or remove the stone using a scope

  • For an enlarged prostate , doctors give you medicines or hormones to reduce the size of your prostate

  • If they can’t remove the blockage, doctors insert a tube through your kidney to drain urine

Doctors will also treat any problems your urinary tract obstruction caused, such as a urinary tract infection or kidney problem.

NOTE: This is the Consumer Version. DOCTORS: Click here for the Professional Version
Click here for the Professional Version
Others also read

Test your knowledge

Loss of Smell
Anosmia is the total loss of smell. Most people with anosmia can taste sweet, sour, salty, and bitter substances but cannot distinguish among specific flavors. This is because the sense of smell makes it possible to distinguish among flavors, not taste receptors as many people erroneously believe. Which of the following is NOT a common cause of anosmia?
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID

Also of Interest

Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID