Hydronephrosis: symptoms, causes, treatment and in pregnancy

The NHS says the symptoms of hydronephrosis may include:

• Pain in the lower back, side or tummy (abdomen).

• Needing to pee more often than usual.

• Difficulty peeing.

• Pee that looks cloudy.

• Blood in your pee.

• A high temperature, or feeling hot, cold or shivery.

The NHS says to ask for an urgent GP appointment or get help from NHS 111 if you or your child have symptoms of hydronephrosis. It is important to get these symptoms checked as soon as possible to find out what is causing them. Call 111 for children under 5.

The NHS says antenatal hydronephrosis does not usually cause any symptoms in the mother or baby during pregnancy.

Kidney Research UK explains that hydronephrosis is when urine builds up inside one or both kidneys, causing them to swell. People of all ages can develop it, as well as unborn babies, which is called antenatal hydronephrosis.

The NHS says it is usually caused by something blocking the flow of pee around the kidneys and bladder and the tubes that carry pee out of the kidneys (ureters).

The NHS lists these causes of a blockage, and Kidney Research UK adds narrowing or blockages that develop before birth, such as pelviureteric junction obstruction (PUJO) or posterior urethral valves (PUV) in males.

• Kidney stones.

• Pregnancy.

• An enlarged prostate.

• Infections, such as a urinary tract infection (UTI).

• An injury or surgery that damages the ureters.

• A blood clot.

• A tumour or some types of cancer.

The NHS says that if a GP thinks you could have hydronephrosis, they may need to do tests to find out what might be causing the symptoms:

• Blood or pee tests to check for infections such as a UTI.

• A rectal examination, to check for an enlarged prostate.

• An X-ray, CT scan or other tests that take pictures of the body to check for a blockage around the kidneys, bladder and ureters.

Kidney Research UK says an ultrasound scan uses sound waves to take pictures of the kidneys and can be used to look for hydronephrosis, and sometimes to identify blockages depending on their type, size and location. Other tests, including blood and urine tests to check for infection and kidney function, and CT scans or X-rays, may be needed to find the cause and look for complications.

The NHS says treatment depends on what is causing it and how severe it is. In adults, the first treatment is usually to drain the pee to help relieve pain and prevent damage to the kidneys. This is done by putting a thin tube (catheter) into the bladder, through either the urethra or a small cut in the tummy. Once the pee is drained, the cause can be treated, for example with medicine to treat infection or surgery to remove a blockage.

Kidney Research UK adds that if the site of the blockage is above the bladder, other ways to drain urine may be needed, such as a stent (a small tube to open up the ureter) or a nephrostomy (a tube that drains urine from the kidney into a collecting bag). Pain relief and antibiotics to fight infection may also be prescribed.

The NHS says hydronephrosis is also common in unborn babies. It is usually found at the 20-week scan and is usually caused by the baby producing more urine in the later stages of pregnancy, which usually goes away on its own. In more severe cases it may be caused by a blockage and may need treatment.

Antenatal hydronephrosis does not usually need any treatment. It often gets better on its own, either during the pregnancy or after the baby is born. If it does not, babies and young children may be given antibiotics to prevent infection, and do not usually need other treatments.

Kidney Research UK says that hydronephrosis in the pregnant person's own kidneys, called maternal hydronephrosis, commonly develops, often due to hormonal changes and an enlarging uterus compressing the ureters. In most cases it does not cause symptoms and is often found during routine pregnancy scans.

The NHS says that if hydronephrosis is treated promptly it does not usually cause any long-term problems, and most people recover quickly. If it is not treated or is severe, it can damage the kidneys and may eventually cause kidney failure, which may need dialysis or a kidney transplant.

On the NHS, suspected hydronephrosis is assessed through your GP, NHS 111 or hospital services, with urology or nephrology teams treating the cause. Antenatal hydronephrosis is followed up through the maternity and paediatric services.

Private urology and imaging services can offer ultrasound, CT and specialist opinion. Ask what is causing the blockage, whether drainage is needed, and how kidney function will be monitored afterwards.