It is very rare that a kidney biopsy has serious complications, or problems. Your child will have tests before the biopsy to check that they are well enough for the procedure. After the biopsy, he or she will be monitored for any complications before they go home.

However, no surgical procedure is completely without risk, and it is important you understand the risks. Your doctor will speak with you about the possible problems with a kidney biopsy before you agree to the procedure.


As a parent or main carer of your child, you will need to give your consent (agreement) before the biopsy. You will need to sign a form that confirms you understand why the biopsy is being done, the alternatives, the complications and risks, and that you agree to the procedure.

Common complications

The following problems happen in more than 1 in 100 biopsies.

Pain and bruising at the biopsy site

Most children have a small amount of pain or a dull ache around the biopsy site – the area where the needle was inserted. You may give your child paracetamol, usually for 1–2 days, to help with any pain, unless your doctor tells you not to. Give the medicine at least 4 hours apart, and do not give it more than four times in 24 hours. You may also talk with your doctor or nurse about other ways to help your child with any pain or discomfort. 

Do not give your chid ibuprofen unless your doctor tells you otherwise.

A few children have bruising around the biopsy site. 

In most children, the bruising and the pain go away after a few days.

See the Medicines for Children leaflet on Paracetamol for mild-to-moderate pain

Blood in the urine

The kidney has many blood vessels (tubes that carry blood round the body). When a needle is inserted, there will almost always be a small amount of bleeding in the kidneys. In most cases, the bleeding stops within the kidney, the body heals naturally, and there are no problems. Often, there is a small amount of blood in the urine, which you may not be able to see – this normally stops after a day.

In up to 10 in 100 kidney biopsies, children have more blood in their urine after a biopsy. Your child’s healthcare team will check for this after the biopsy and before your child goes home. Your child’s urine may look pink or red. Sometimes there is blood in the urine for about 24 hours after the biopsy and in most children this goes away without needing any treatment.

Blood clots in the urine

One way the body works to stop bleeding is to form a blood clot – the blood clumps together. If your child has visible blood in his or her urine, he or she will be encouraged to drink plenty of fluids and go to the toilet regularly to help stop blood clots forming in the urine.

If your child has signs of blood clots, your doctor may use an ultrasound scanner to find the clots. The clots are almost always small enough to pass into the bladder, where urine is stored. Sometimes, clots need to be “flushed out” of the body using a urethral catheter, a long plastic tube. Your doctor will place the catheter through your child’s urethra (the tube that he or she wees out of) and into the bladder, so that the blood clots can be removed. This is needed in 2 in 100 children who have had a kidney biopsy.

Inadequate sample

Occasionally, the doctor is not able to get a good enough sample in the first biopsy. This can happen in up to 5 of 100 biopsies. If this happens, your child may need to have another biopsy. Your doctor will explain what should happen next.

Rare problems

The following problems happen in fewer than 1 in 100 biopsies.

Heavy bleeding

A small number of children have very heavy bleeding, and there is a large amount of blood in their urine.

Some of these children need to have a blood transfusion. This is only needed in about 1 in 100 children who have had a biopsy. In this procedure, blood is taken from a donor (a person donating some of his or her blood) and put into your child’s body (as the recipient). Usually, a plastic tube (a cannula) is inserted into a blood vessel in the arm, and the blood is passed through. Blood is usually given over 3–4 hours.

In less than 1 in 100 children who have had a biopsy the bleeding does not stop on its own and an operation is required to stop the bleeding.


A very small number of children get an infection following a biopsy. This can be in the skin around the biopsy site or, more rarely, in the blood around the kidney. You can help avoid this by keeping the biopsy site clean and dry for a few days after the procedure.

If your child gets an infection, he or she will need to take antibiotics, medicines that kill the germs that cause the infection. Very occasionally, children need a minor operation to drain, or remove, the infected blood.

Joining of two blood vessels in the kidney (fistula)

The body has two types of blood vessels, which carry blood around the body. 

  • Arteries carry blood from the heart to the rest of the body. 
  • Veins carry blood from the body back to the heart.

Very occasionally, a biopsy needle damages the walls of a nearby artery and vein. This causes an abnormal connection between the two blood vessels, which is called an arteriovenous fistula, or fistula.

Most of the time, a fistula causes no problems, and the connection closes on its own. Rarely, it leads to bleeding or problems with blood pressure. If your child has these problems, your healthcare team will use an ultrasound scanner to find out whether there is a fistula. Rarely, children need surgery to treat this. 

Going back to hospital

For most children with complications after a biopsy, the problems are found while they are still in hospital. Your doctor will give you information on what to do when you get home to avoid any problems, and what to look out for. Approximately 1 in 100 children need to go back into hospital.