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Hydronephrosis - Causes, Symptoms, Diagnosis, and Treatment

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Hydronephrosis is a condition in which one or both kidneys swell as a result of improper drainage of urine. To know more about it, read the following article.

Medically reviewed by

Dr. Manzoor Ahmad Parry

Published At August 22, 2022
Reviewed AtMay 16, 2023


Hydronephrosis develops when urine cannot be drained out of the kidney resulting in the build-up of urine, causing the kidneys to swell. It can affect one or both the kidneys and may occur at any age. It may occur in any part of the urinary system from the kidney, ureter, bladder, and urethra. Obstruction in any of these areas will obstruct the urine flow, thereby causing hydronephrosis. Chronic untreated hydronephrosis will impair kidney function and progress to renal failure.

What Is Hydronephrosis?

Hydronephrosis is a condition affecting the kidneys due to incomplete drainage of urine from the kidneys. It is caused as a result of a blockage in the ureter that drains urine from the kidney or as a result of an anatomic defect that obstructs the urine drainage.

What Is the Epidemiology of Hydronephrosis?

Hydronephrosis can occur at any age without any gender prediction. In children, it is most commonly due to obstruction caused by anatomical defects. Whereas in adults, it occurs mostly as a result of kidney stones obstructing urine drainage. Antenatal hydronephrosis is reported to be present at least 1 in every 100 pregnancies.

How Is Hydronephrosis Classified?

Based on the Duration:

  • Acute Hydronephrosis - It is developed in a short duration.
  • Chronic Hydronephrosis - Present for a longer duration.

Based on the Amount of Obstruction:

  • Partial Hydronephrosis - Seen when there is only a partial obstruction of the urinary tract.
  • Complete Hydronephrosis - When there is complete obstruction of the urinary tract.

Based on the Side of the Kidney Affected:

  • Unilateral Hydronephrosis - One kidney is affected.
  • Bilateral Hydronephrosis - Both the kidneys are affected.

Based on the Age of Occurrence:

  • Adult Hydronephrosis - Occurs in the adult age group.
  • Antenatal Hyde\ronephrosis - Occurs in unborn babies.

What Is Antenatal Hydronephrosis?

Antenatal hydronephrosis is a type of hydronephrosis seen in unborn babies diagnosed during pregnancy in routine ultrasound examinations.

What Is the Etiology of Antenatal Hydronephrosis?

Studies state that it may be caused due to,

  • The excess amount of urine is produced by the babies in the later stages of pregnancy.
  • Any obstruction in the flow of urine from the kidney to the bladder.
  • Blockage in the bladder that prevents the drainage of urine.
  • Backflow of urine from the bladder into the kidney.

What Is the Etiology of Adult Hydronephrosis?

The most common causes include,

  • Renal Calculi - Kidney stones are the most common cause of hydronephrosis, stones that are wedged in the urinary tract or the kidney may cause obstruction to the flow and drainage of urine, causing hydronephrosis.
  • Narrowing of the Urinary Tract - Narrowing or stricture of the urinary tract caused due to birth defects, injury, infection, etc.,
  • Benign Prostatic Hyperplasia - This is a condition characterized by inflamed prostate glands which compress the ureter, causing obstruction and diminished drainage of urine, leading to hydronephrosis.
  • Cancer - Tumors arising in the ureter, bladder, uterus, or the organs close to the urinary tract can cause obstruction, thereby disrupting the urine drainage.
  • Pregnancy - The expansion of the uterus can put pressure on the ureter, causing obstruction to the flow of urine.
  • Cystocele -This is a condition seen exclusively in women. Also known as the fallen bladder, where the wall between the bladder and the vagina weakens, leading to the dropping down of the bladder into the vagina.
  • Urterocele - This is a condition in which the lower part of the ureter protrudes into the bladder, thus disrupting the urine flow.
  • Blood Clots - Sometimes, blood clots develop in the kidneys, causing an obstruction.
  • Vesicoureteral Reflux - This is a condition in which there is the backflow of urine from the bladder into the kidneys.
  • Uterine Prolapse - This is a condition in women where the uterus sags out of its normal position, causing pressure in the ureter, thereby promoting hydronephrosis.

What Are the Symptoms of Hydronephrosis?

It usually does not produce any symptoms, often diagnosed during routine scans during pregnancy. After birth, it remains asymptomatic and resolves on its own, but if the child develops the symptoms of urinary tract infection such as fever, chills, etc., it should be noticed.

In adults, it may produce symptoms such as,

  • Intense pain in the back.
  • Nausea.
  • Vomiting.
  • Weakness.
  • Frequent urination.
  • Painful urination.
  • Hematuria (blood in the urine).
  • Fever (due to urinary tract infection).

How Is Hydronephrosis Diagnosed?

Steps in diagnosis include the following:

  • History - Medical history would help in relating the symptoms of the disease and the family history to know if anyone is affected by the same condition.
  • Clinical Examination - Clinical examination involves rectal examination in men to check for any swelling in the prostatic glands. Pelvic examination is done in females to check for any abnormalities in the uterus and ovaries.
  • Urine Test - To check for any symptoms of infection, presence of bacteria, blood and stone crystals.
  • Blood Test - A complete blood count will help to check for infection. Serum creatinine, urea levels, and the glomerular filtration rate are analyzed to check for the functioning of the kidney.
  • Kidney Ultrasound - To diagnose the possible cause of hydronephrosis.
  • Computerized Tomography (CT) and Magnetic Resonance Imaging (MRI) - Additional imaging studies to understand the etiology better.

How Is Hydronephrosis Treated?

The main aim of treatment is to allow proper drainage of urine from the kidney. Treatment depends on the primary problem causing the condition.

  • Pregnancy and Antenatal Hydronephrosis - Usually do not require any treatment as they will subside on their own.
  • Acute Hydronephrosis - Is treated by inserting a stent or nephrostomy tube into the kidney through the skin to drain the excess urine.
  • Kidney Stones - Hydronephrosis caused by kidney stones should be removed to prevent further urine build-up in the kidney. They can be removed by:
    • Shock Wave Lithotripsy - High energy shock waves are transmitted from the machine to break the stones into smaller pieces which are then eliminated from the body.
    • Ureteroscopy -This method is often preferred in removing stones in the bladder and lower half of the ureter. In this, a thin tube with special instruments is inserted into the ureter to break and remove the stones.
    • Surgery - In the case of larger stones, they are removed surgically.
  • Cancer - Hydronephrosis caused due to cancer can be treated by chemotherapy or radiotherapy to reduce the size of the tumor or surgery to remove the entire mass.
  • Enlarged Prostate or Blockage in the Ureter - May be treated surgically.
  • Antibiotics - Are given to treat or prevent urinary tract infections.
  • Analgesics - Are prescribed to relieve pain.


Hydronephrosis is an easily manageable condition; the prime aim of treatment should be focused on removing the excess urine and relieving the pressure. If left untreated, it may cause permanent kidney damage leading to renal failure. Promptly treating the underlying cause reduces the chance of developing hydronephrosis. The overall prognosis of hydronephrosis is reported to be good.

Dr. Manzoor Ahmad Parry
Dr. Manzoor Ahmad Parry



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