Hydronephrosis – Facts You Must Know



(Distension of Renal Calyces & Pelvis)

Hydronephrosis is the distension of the renal calyces and pelvis due to accumulation of the urine as a result of the obstruction to the outflow of the urine mostly distal to renal pelvis.

What is Hydronephrosis?

Hydronephrosis is the condition, not the disease which typically occurs when the urine outflow from the kidney to the bladder is obstructed. The obstruction leads to build up of urine in the kidney pelvis and calyces (the spaces present in the kidney) and causes stretch or distension and ultimately swelling of the kidney. This swelling mostly affects only one kidney but both kidneys may be involved. As the swelling and distension progress, it involves the ureter (the connecting tube of the kidney to bladder), a condition termed as hydroureter.

In simple words, hydronephrosis implies, kidneys are overfilled with urine what so ever the cause is.

Causes & Risk Factors of Hydronephrosis

As to clear, hydronephrosis is not the disease itself, rather it is a condition caused by many internal and external factors that affect the kidneys and it collecting tubules system.
Various common causes that lead to hydronephrosis are;

  • Kidney stones are the common causes of hydronephrosis in both men and women
  • Acute unilateral obstructive uropathy – sudden development of obstruction in the ureter which causes hydronephrosis. The risk factors may be kidney stones, scarring by injury and inflammation or by formation of blood clot
  • Kink formation or twisting in the ureteropelvic junction (area where ureter connects with pelvic – connection of ureter and kidney)
  • Tumor mass in the ureter (exerting pressure and causing obstruction)
  • Narrowing of ureter either by birth (congenital) or by injury or trauma (acquired)

Certain causes are gender specific for hydronephrosis, means these affect only men or women.

Causes in Men

In men, the most common causes of hydronephrosis are;

  • Kidney stones (common causes of hydronephrosis in both men and women)
  • Benign swelling of prostate gland (BPH – Benign Prostate Hypertrophy)
  • Prostate cancer

Both these conditions exert pressure on ureter, a tube connecting kidney to bladder and may block it resulting into urine outflow obstruction.

Causes in Women

In women, the common causes of hydronephrosis are:

  • Pregnancy is physiologic cause – enlarged uterus or womb may exert pressure on ureters and block it
  • Tumors of reproductive organs like ovarian cancer, uterine cancer and cervical caner
  • Tumors of urinary tract i-e kidney cancer and bladder cancer

Bladder cancer disrupt the normal function of urinary bladder and cause back flow of urine by vesicoureteric reflex.

Signs & Symptoms of Hydronephrosis

The most common symptoms is the severe pain in the back and side of your body b/w your ribs and pelvis (area is medically termed as lumber area). However, the symptoms depend upon the way of onset whether the urine blockage occurs spontaneously (acute hydronephrosis) or slowly over a time i-e gradually (chronic hydronephrosis).
Generally, the symptoms you may experience are;

  • Pain in the abdomen or flank
  • Nausea and vomiting
  • Pain with urination
  • Increased frequency of micturition (urination)
  • Increased urgency of micturition
  • Urinary tract infections (UTI)
  • Fever 38oC (100.4oF) or above

In Acute Condition

Signs and symptoms you may experience are;

  • You will experience sever pain in the back and side of your body b/w your ribs and pelvis (lumber area).
  • Pain will be only on the effected side if one kidney is involved.
  • In some cases, pain in referred to lower aspect, to testicles in males and to vagina in females.
  • Pain becomes worsens with drinking more water or fluid.
  • Sometimes, pain is associated with nausea and vomiting.
  • Fever 38oC (100.4oF) or above if you also get infection (UTIs)

In Chronic Condition

Signs and symptoms vary a great;

  • You may feel the same signs as in the case of acute hydronephrosis.
  • May be no symptom at all (chronic hydronephrosis may go unnoticed until it becomes advanced).
  • May be a dull pain on your effected side of the body
  • Increased frequency of urination and urge to urinate
  • Pain with urination
  • You may complain of less urination compared to routine days.

Severity of symptoms also depends upon the site of obstruction, duration of obstruction and extent to which kidneys are stretched.

When to See Your Doctor

You need see your doctor if you have persistent and sever pain on the side and back of your body in lumber area or flanks. The change in your micturition habits and high grade fever of 100.4oF or above also favour, you need consult your physician.

How Hydronephrosis is diagnosed?

History, clinical assessment of the patient state and thorough general physical examination (GPE) are helpful in making the diagnosis but a definite diagnosis is made upon ultrasound examination or computed tomographic Scan (C.T scan). These investigations help taking a closer look and localize the site of obstruction.
Other investigation that aid in making diagnosis are;

  • CBC – to check for the infections
  • Urine analysis – to check for infections and blood in urine (hematuria)
  • Intravenous urography – X-ray of the kidneys with dye injection intravenously
  • C.T scan


Untreated cases of hydronephrosis progress to kidney scarring and loss of its normal function. If one kidney is involved, the condition is compatible with life, as the other kidney is functioning well. But both kidney may be affected by hydronephrosis and result into total kidney failure and require dialysis and immediate kidney transplant.
Some complications are described as;

  • Kidney scarring and loss of normal function
  • Total kidney failure
  • Morbid kidney may be infected by some bacteria and cause further complications
  • Cancer may arise in such kidney (failed kidney caused by hydronephrosis)

If failed kidney is superimposed by some infection and cancer, it require surgical removal.


The treatment of hydronephrosis aims at removing the cause that is causing the urinary obstruction. Your treatment option depends upon the cause of your obstruction. However, certain points remain common for treating all kind of obstruction.

  • Preventing urine retention to avoid build up of excess urine in renal pelvis to avoid distension
  • Preventing damage to kidney structure and functions.
  • Getting rid of cause that is causing hydronephrosis in each case.

The most cases of hydronephrosis are treatable with the help of surgical procedures. Certain techniques are used clinically are discussed below.

Urine Drainage

The first step in treating hydronephrosis is to drain out the urine. It helps in preventing damage to kidney and easing pain. A foley catheter (thin rubber tube) is inserted into the bladder through urethra and urine is passed out through it. Catheter can be directly inserted into the kidney through a small incision in your skin. This allows the urine to flow out of kidney and relieve the pressure.

Eradication of Underlying Cause

The urine drainage relieves pressure in the kidney and provides us some time. Now the second and important step in to treat the underlying cause of blockage.

  • Most common cause of hydronephrosis is the ureter blockage and the surgical method or technique to treat is called ureteral stenting. The small metallic rings (stent) are introduced into the ureter without major incision which fit in the site of blockage after opening it and making it wide. In other procedure, a small tube is placed inside the ureter which bypasses the blockage site. Now the urine has been drained and the ureter unblocked, certain measures would be considered to avoid recurrence of the condition.
  • When the kidney stones are the reason of blockage, sound waves or laser are used to smash these into small pieces which pass out of body in urine and blockage in relieved.
  • In case of swollen prostate, medication are used to treat it and if unresponsive or BPH or prostate cancer is found, surgical removal of prostate is the cure to hydronephrosis.
  • Similarly, cervical cancers, ovarian cancers and uterine cancers may the underlying causes of hydronephrosis so these conditions are treated with surgical removal or if possible by radiotherapy and chemotherapy.
  • Pregnancy may be the cause of hydronephrosis, and in this case little help we can, to treat hydronephrosis and protocol is to wait and see. We allow pregnancy to take its natural course and regular urine drainage by catheterisation is somewhat helpful in preventing kidney damage.

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Hydronephrosis – Facts You Must Know
Hydronephrosis – Facts You Must Know

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