Hydronephrosis – a blocked and swollen kidney

Hydronephrosis is swelling (dilation) of the renal pelvis and calyces – the parts of the kidney that collect urine – which happens when urine cannot drain freely and builds up in the kidney. It is not a disease in its own right but a sign of an obstruction somewhere along the urinary tract, and its cause needs to be found.

It occurs at any age – from the unborn baby to old age, when the most common causes are stones and an enlarged prostate. Mild hydronephrosis is often harmless and temporary, but a prolonged blockage thins the kidney tissue and permanently reduces kidney function, and combined with infection it is an emergency.

What hydronephrosis is

Urine collects in the calyces and the renal pelvis and travels down the ureter to the bladder. An obstruction at any level makes urine build up above it; the pressure stretches the renal pelvis and, over time, compresses and thins the kidney tissue.

Hydronephrosis can be mild, moderate or severe, and by how it develops – acute (over hours, most often with a stone) or chronic (over months, often painless). Hydronephrosis on both sides points to a problem at the level of the bladder or urethra, for example an enlarged prostate. Not every dilation means a blockage – in pregnancy, when a lot of urine is produced and with some anatomical variants, the renal pelvis is wide without the kidney being harmed.

Symptoms

Chronic hydronephrosis is often found by chance, without symptoms. Possible symptoms:

• a dull ache or heaviness in the lower back that gets worse after drinking a lot of fluid;
• severe pain that comes in waves with a sudden blockage – renal colic;
• blood in the urine;
• repeated urinary tract infections;
• when both kidneys are affected – a weak stream, passing less urine and swelling (oedema).

The following are urgent: a temperature and shivering together with lower back pain (infection in the blocked kidney), urine output stopping, being unable to urinate with a full bladder, and a blockage when you have only one kidney – go to an emergency department or call 112 (the European emergency number) without waiting for a booked appointment.

Causes and risk factors

In adults the leading cause is stones. Next come an enlarged prostate and urinary retention, narrowing of the ureter after a stone, surgery or radiotherapy, urethral stricture, impaired bladder emptying in neurological diseases, and tumours in the pelvis that press on the ureter. In children and young people the most common causes are a congenital narrowing where the renal pelvis joins the ureter and urine flowing back from the bladder to the kidney (vesicoureteral reflux), and in pregnancy – pressure from the womb.

The risk is higher if you have had stones before, pelvic surgery or cancer, and in men with long-standing, untreated urinary symptoms.

Diagnosis

The main method is ultrasound – quick, painless and without radiation. During an ultrasound scan at Dr Penev’s practice in Plovdiv or Karlovo, both kidneys, the bladder and the prostate are examined: the degree of dilation, the thickness of the kidney tissue, any stones and the residual urine (urine left in the bladder after urinating) give clues to where the obstruction is.

A urine test and blood tests for kidney function are added. If the cause is unclear, a CT scan is ordered, with contrast if needed. An isotope scan (renography) measures the function of each kidney and whether drainage really is obstructed, which guides the choice between monitoring and surgery.

Treatment

Treatment depends on the cause, the degree of swelling, kidney function and whether there is an infection. Mild hydronephrosis without a blockage and without symptoms is monitored with follow-up ultrasound scans.

If there is a blockage with infection, urine output has stopped or kidney function is getting worse, the kidney is unblocked urgently. At the Department of Urology at Kaspela University Hospital (UMBAL Kaspela), Plovdiv, this is done with a ureteric stent – a thin tube running from the kidney to the bladder – or with a nephrostomy – a drain through the skin of the lower back. The stent stays in for a limited time and is then removed as an outpatient procedure.

The lasting solution is to remove the cause: stones are removed with endoscopic methods or broken up from outside the body (shock wave lithotripsy); a congenital narrowing of the renal pelvis is corrected with reconstructive surgery (pyeloplasty), often laparoscopic; narrowings of the ureter are widened endoscopically or operated on; an enlarged prostate is treated with medication or surgery. A kidney that has lost almost all its function and causes pain or infections is sometimes removed, usually laparoscopically.

Hydronephrosis in children

Dilation found on an ultrasound scan of an unborn baby or an infant is most often mild and returns to normal during the first one or two years without treatment. Regular ultrasound scans are needed; with more marked dilation, an isotope scan and sometimes preventive treatment against infections; and surgery when kidney function drops or the dilation increases. Dr Penev also examines and follows up children – see the paediatric urology consultation.

When to see a urologist

Book a consultation if an ultrasound report describes a dilated renal pelvis, if you have pain or heaviness in your lower back, repeated urinary infections or blood in the urine, or if you are a man with a weakened stream and a feeling that your bladder does not empty completely – a silent blockage caused by the prostate damages the kidneys gradually and without pain.

Prevention

Hydronephrosis is prevented by treating its causes in good time – stones, an enlarged prostate, urinary infections and urinary retention. Do not put up with difficulty urinating for years, and do not miss your follow-up appointments after a stent or surgery.

A swollen kidney is a warning sign, not a verdict – when it is unblocked in time, its function is preserved in most cases. If your ultrasound has shown hydronephrosis, book an appointment with Dr Penev in Plovdiv or Karlovo to find the cause and get a treatment plan.