What is Ureteral Obstruction

  • Hania Beg  MSc Clinical Drug Development, Queen Mary University, London, UK
  • Isobel Cronshaw  BEng in Biomedical Systems Engineering, University of Warwick

Getting diagnosed with a ureteral obstruction might sound daunting and disconcerting. This article will try to explain all the relevant details related to this so that you can better understand this condition and know what to expect from its treatment. It is important to observe any symptoms you might be experiencing in order to get prompt and efficient treatment. 

Ureters anatomy

A ureteral obstruction is defined as a blockage which is present in any one of your ureters.1 Now you’re probably wondering what exactly a ureter is. If we start with the kidneys, their function is to filter our blood to remove waste products in the form of urine. The function of the ureters is to carry the urine from our kidneys to our urinary bladder.

There are two bilateral ureters present in our bodies: two thick tubes which begin at the kidneys and end at the urinary bladder. Each ureter drains one kidney, becoming narrower in dimension as they descend down the abdominal cavity, all the way down into our pelvic cavities. Both ureters pierce the urinary bladder at an oblique angle (not a right angle), which creates a sort of one-way valve, preventing the backflow of urine into the ureters. Ureters need to remain unblocked in order to maintain the proper flow of urine. 

Types of ureteral obstruction 

Intrinsic ureteral obstruction: the ureters can become blocked by a number of intrinsic causes. One of these causes is ureteral stones. These stones are irregular-shaped masses or crystals that usually arise from the kidneys and travel down to block one of the ureters.

Stones can form in our kidneys as a result of increased minerals in our urine, which can build up to form stones. Calcium stones are the most common type, but they can also be formed by uric acid, struvite and cystine. There are certain predisposing factors for the formation of stones, and these include a previous episode of ureteral stones, a family history of stones, drinking very little water, having diabetes, or having polycystic kidney disease. 

Some stones are very small and pass unnoticed through our urinary system. When these stones are large enough to induce a blockage, they can cause:

  • Severe intermittent pain, mostly in the lower back and the sides below the ribs, with radiating pain to the abdomen or groin
  • Frequent urination
  • Small amounts of urine
  • Cloudy and/or discoloured urine (brown or red)
  • Nausea and vomiting 

Tumours can also cause an intrinsic blockage in the ureters, although ureteral cancer is rare. It will cause the same symptoms as ureteral stones, but there might also be blood present in the urine, as well as symptoms such as fatigue and weight loss.

Scarring, injury and trauma can also cause intrinsic blockages in the ureters.

A child can be born with a ureteral obstruction. This obstruction develops due to a narrowly formed junction between the ureter and the kidney, which is called congenital ureteropelvic junction obstruction.3 The symptoms would include all those listed above, with an addition of failure to thrive and poor growth.

Extrinsic ureteral obstruction: extrinsic factors of ureteral blockage are factors which are located outside the ureters but cause restriction and narrowing of the urinary pathway in the ureters. One such factor can be a large tumour which could develop on nearby structures. 

Problems in the gastrointestinal tract can cause a blockage in the ureters such as swelling of the appendix, diverticulitis, or Crohn's disease

In that assigned female at birth, something completely natural, such as pregnancy, might cause ureteral blockage or medical conditions such as endometriosis, uterine prolapse, or any abnormal growth in the womb. 

Vascular diseases such as blood clots could also form or cause a ureteral blockage. 

Despite the causes being extrinsic, the symptoms would be the same as for intrinsic causes. However, there might also be the addition of some systemic symptoms that are associated with the underlying condition causing the blockage. 

Complications arising from ureteral obstruction 

Hydronephrosis:4 when there is a blockage in one of the ureters, urine cannot flow along its natural path which is from the kidneys, through the ureters and into the urinary bladder where it is excreted via the urethra. Due to this blockage, urine starts to accumulate in the kidney and causes this kidney to swell. There may or may not be symptoms in this condition but when there are, the symptoms would be:

  • Pain in the sides and back, which may radiate to the abdomen or groin is worse after drinking a lot of water
  • An urgent and frequent need to urinate 
  • Blood in urine
  • Nausea and vomiting
  • Fever

At times, hydronephrosis might not require any treatment, and your doctor might opt to simply wait and watch. When the condition is severe, a catheter (a narrow tube inserted into the urethra) might be inserted to drain the urine and relieve the pressure on the kidneys. After this, the cause of the blockage will need to be treated to prevent hydronephrosis from happening again. 

Urinary Tract Infections (UTIs): a UTI is an infection that can occur anywhere in the urinary tract, and if there is a blockage in your ureter, it could lead to a UTI. Symptoms include: 

  • Frequent and urgent need to urinate
  • A burning pain/sensation while passing urine (dysuria)
  • Cloudy urine or blood in the urine (hematuria)
  • Pain in the abdomen, back or sides
  • Fever with chills 

A UTI can be easily treated with a course of antibiotics. However, a UTI associated with a ureteral obstruction needs to be treated as soon as possible in order to prevent further complications such as sepsis.

Diagnosis of ureteral obstruction 

After taking a detailed history and performing a physical examination, your doctor might order further tests to confirm the diagnosis. These tests might include:5

  • A blood and urine test to check for infections and the levels of creatinine (which are an indicator of kidney malfunction)
  • An ultrasound.
  • Bladder catheterisation. This involves injecting a dye via a catheter into the bladder, and then performing an x-ray of the urinary system. 
  • Cystoscopy. A small light and camera are inserted in the urethra to visualise the urinary system.
  • MRI or CT for more detailed imaging.

Treatment and management 

When the case of ureteral obstruction is not severe, or it is a partial blockage, treatment might not be needed. Conservative measures might suffice, such as drinking plenty of water and managing any pain with simple pain relievers. 

If the blockage is severe, the following treatments might be needed:

Medical interventions: The pain associated with ureteral obstruction can be relieved by analgesics such as paracetamol and ibuprofen. If an infection is present, it will be treated with a course of antibiotics. 

If the obstruction also requires drainage of the urine from your body, your doctor might recommend a ureteral stent. This stent is a narrow tube which is inserted into the ureter to keep it open and to allow the urine to drain. If the blockage affects the urinary bladder, or if constant drainage is needed, a catheter might be inserted. This is a tube inserted into the ureters via the urethra, to allow the drainage of urine into an external bag. 

In severe cases, your kidneys might need to be drained directly, so a small incision is made in your back, and a tube is inserted in to directly drain the kidneys. 

Surgical interventions: if medical interventions do not suffice, surgical interventions might be needed. This can involve an endoscopic surgery which can be used to diagnose and treat a blockage. In this a small lighted scope that is passed into the urinary system via the urethra. A stent is placed where the blockage is in order to allow the flow of urine. 

Depending on the severity of the condition, your doctor might decide to go for an open abdominal surgery instead, in which the urinary system is accessed directly via an incision in the abdomen. 

If the obstruction is being caused by kidney stones, a procedure called ureteroscopy with laser lithotripsy6 is done. In this, a narrow, either flexible or rigid scope is inserted through the urethra into the urinary system to directly visualise the stones via a video monitor. Once the stones are located, the laser lithotripsy uses energy pulses from a laser beam, to break down the stone into much smaller pieces which can be easily passed. 


Ureteral obstruction is not a major cause for concern, but it can be uncomfortable or even painful. It is important to see your doctor if you experience any of the symptoms that are mentioned in this article because early treatment and interventions can help to prevent kidney damage. Some cases can be managed without any treatment, and some cases that are more severe might require further medications or surgery. 

It is important to drink plenty of water and limit your salt intake to prevent the formation of kidney stones. Maintaining a healthy weight can also help to keep your body functioning properly.


  • Ureteral obstruction - Symptoms and causes. Mayo Clinic [Internet]. [cited 2024 Feb 22]. Available from: https://www.mayoclinic.org/diseases-conditions/ureteral-obstruction/symptoms-causes/syc-20354676
  • Ureteral Stones: Symptoms, Diagnosis, Treatment & Prevention. Cleveland Clinic [Internet]. [cited 2024 Feb 22]. Available from: https://my.clevelandclinic.org/health/diseases/16514-ureteral-stones
  • Ureteropelvic junction obstruction [Internet]. 2019 [cited 2023 Oct 2]. Available from: https://www.hopkinsmedicine.org/health/conditions-and-diseases/ureteropelvic-junction-obstruction
  • Hydronephrosis. nhs.uk [Internet]. 2018 [cited 2024 Feb 22]. Available from: https://www.nhs.uk/conditions/hydronephrosis/
  • Tabib C, Nethala D, Kozel Z, Okeke Z. Management and treatment options when facing malignant ureteral obstruction. Int J of Urology [Internet]. 2020 Jul [cited 2023 Oct 2];27(7):591–8. Available from: https://onlinelibrary.wiley.com/doi/10.1111/iju.14235
  • Ureteroscopy with Laser Lithotripsy Treatment for Kidney Stones Washington, D.C., Maryland & Virginia [Internet]. [cited 2024 Feb 22]. Available from: https://www.dcurology.net/procedures/ureteroscopy-with-laser-lithotripsy.php#:~:text=Ureteroscopy%20with%20laser%20lithotripsy%20is,small%20pieces%20and%20passed%20easily.
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Hania Beg

MSc Clinical Drug Development, Queen Mary University, London, UK

Hania is a medical doctor (MBBS), with a MSc in Clinical Drug Development. She has got extensive medical knowledge with prior experience in the Heathcare sector and an in dept understanding of drug development and pharmaceuticals. She is ICH-GCP certified with a special interest in medical writing and research.

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