Hydronephrosis - What is it?

Hydronephrosis is a condition resulting from swelling or dilation of the urine collecting structures in one or both kidneys. Usually due to a blockage restricting urine flow from the kidney, possibly causing impairment of the kidney’s function.

There are two stages of hydronephrosis, acute and chronic. Those with acute hydronephrosis, once the problem is corrected, normally regain full renal function. Chronic hydronephrosis sufferers that have lost renal function from an obstruction, after removal of the obstruction, may never regain full renal function.

When urine backflows into the kidneys causing dilation, an additional cause of hydronephrosis, it is known as Reflux. Reflux is most commonly seen in infants and children. Most children outgrow this condition.

It appears the cause of hydronephrosis in females and males may be different. In females, most often it is caused by gynecologic cancers and pregnancy. In men the most common causes are obstruction, prostatic hypertrophy, and prostate cancer. However, other causes could be a blockage that is present at birth (congenital), a kidney stone or stone in the ureter (nephrolithiasis), a blood clot, scar tissue or tumor in or around the ureter, and enlarged prostate gland, or pregnancy.

Hydronephrosis is normally diagnosed using x-rays of the kidneys, dye (excretory urogram), ultrasound or CT scan, MRI (magnetic resonance imaging), cystoscopy and ureter catherization with dye injection.

Hydronephrosis can be a very treatable and a non serious condition, but could become life-threatening if infection develops with the condition.
Hydronephrosis can be diagnosed during an evaluation of an unrelated process, although patients usually have some signs or symptoms of the condition. Symptoms may include nausea and vomiting, back pain and abdominal mass, fever, urinary tract infection, and changes in urinary frequency and urgency. The condition can affect one (unilateral) or both (bilateral) kidneys. Symptoms may be more prevalent in patients with bilateral hydronephrosis. If left untreated it can cause hypertension, loss of renal function, and sepsis.

Treatment depends on the severity of the condition and the determined cause. Sometimes the cause of hydronephrosis will resolve itself, such as blood clots and kidneys stones. Some blockages may need to be surgically removed, but very seldom is the kidney itself removed.

Treatment usually consists of prescription medication to help with pain and to prevent infection. If the condition requires surgery, it is usually only minimally invasive or an open surgical treatment. In more rare cases, surgery to insert a urethral stent is conducted. The procedure is usually performed along with cystoscopy and retrograde pyelography. Stents may be used to bypass an obstruction, and aid in easing swelling of the kidney or ureter. Certain causes of hydronephrosis still require treatment with open surgery.

With the advancement of ultrasound, doctors are able to evaluate the kidneys of unborn babies more closely, allowing for diagnoses of hydrophronosis during pregnancy. An expecting mother is referred to an urologist for evaluation if there is a reason for concern. Doctors may conduct more tests to determine the cause and severity of the condition after birth. In rare cases surgery can be conducted to correct the condition during pregnancy. However, due to the risk of preterm labor this is not often recommended.