Diagnosis of Wilms tumour

Diagnosis is the process of finding out the cause of a health problem. Diagnosing cancer often means first ruling out other health conditions that share similar symptoms with cancer. It can be a very worrying time for you, your child and your loved ones. Sometimes this process is quick. Sometimes it can feel long and frustrating. But itʼs important for doctors to get all the information they need before making a diagnosis of cancer.

Diagnosing Wilms tumour usually begins with a visit to your childʼs doctor. The doctor will ask about any symptoms your child has and do a physical exam. Based on this information, the doctor may refer your child to a specialist or order tests to check for Wilms tumour or other health problems.

The following tests are usually used to diagnose or rule out Wilms tumour. Many of the same tests used to diagnose cancer are used to find out the stage (how far the cancer has spread). The doctor may also order other tests to check your childʼs general health and to help plan treatment.

Your childʼs health history is a record of the symptoms and risks and all the medical events and problems that they have had in the past. The doctor will ask questions about your childʼs health history, including their personal or family history of:

• Wilms tumour
• WAGR syndrome
• Beckwith-Wiedemann syndrome
• Denys-Drash syndrome
• Simpson-Golabi-Behmel syndrome
• Perlman syndrome
• Frasier syndrome
• Bloom syndrome
• Li Fraumeni syndrome
• aniridia (the iris of the eye has not developed)
• hemihyperplasia (one side of the body is bigger than the other)
• undescended testicles
• hypospadias (the urinary opening is on the underside of the penis rather than at the tip)

A physical exam allows the doctor to look for any signs of Wilms tumour. During a physical exam, the doctor may feel your child’s abdomen for any lumps or swelling.

Find out more about physical exams.

A urinalysis is a group of tests done to examine the urine (pee). It finds and measures substances such as electrolytes, sugar (glucose), proteins, blood, cells and bacteria. It may also be called a urine test.

If there is blood in the urine, it means that there is bleeding into or inside of the kidneys or urinary tract.

Find out more about a urinalysis.

A complete blood count (CBC) measures the number and quality of white blood cells, red blood cells and platelets. A CBC is done to check for anemia (low red blood cell count).

Find out more about a complete blood count.

Blood chemistry tests measure certain chemicals in the blood. They show how well certain organs are working and can help find problems. Blood chemistry tests used to diagnose Wilms tumour include the following.

Blood urea nitrogen (BUN) and creatinine may be measured to check how well the kidneys are working. Increased levels could mean that the kidneys are not working well, which may be because of cancer.

Glomerular filtration rate (GFR) is another test used to check how well the kidneys are working. It measures how much blood is passing through the glomeruli (the tiny filters in the kidney that remove waste from the blood). To estimate the GFR, the creatinine level is combined with several other factors such as age, sex, height, weight and ethnicity. A low GFR means that the kidneys are not filtering the blood very well. A very high GFR is a sign that the kidneys are working harder than usual to filter the blood, which can mean they are at risk of failing.

Calcium and phosphorus levels may be high if there is kidney disease or if cancer has spread to the bone.

Alkaline phosphatase levels may be high if cancer has spread to the bones or liver.

Liver function tests may be done to see how well the liver is working. Some chemotherapy drugs can only be given if the liver is working well.

Find out more about blood chemistry tests.

An ultrasound uses high-frequency sound waves to make images of parts of the body. It’s used to look at the kidneys and surrounding tissues and organs.

An abdominal ultrasound is often the first imaging test a doctor orders if they suspect Wilms tumour. Itʼs a painless test that allows them to see the kidneys and the whole abdomen.

Find out more about ultrasounds.

A computed tomography (CT) scan uses special x-ray equipment to make 3D and cross-sectional images of organs, tissues, bones and blood vessels inside the body. A computer turns the images into detailed pictures.

An abdominal CT scan is used to look more closely at the kidneys. A CT scan is also useful for checking whether cancer has spread to other organs or tissues, such as blood vessels, lymph nodes, the other kidney, the liver or the lungs.

Find out more about CT scans.

Magnetic resonance imaging (MRI) uses powerful magnetic forces and radiofrequency waves to make cross-sectional images of organs, tissues, bones and blood vessels. A computer turns the images into 3D pictures.

An abdominal MRI is used to show more detailed images of the kidneys, including the major blood vessels nearby. An MRI can also be used to check if the cancer has spread from one kidney to the other, to the liver or to the brain.

In most cases the doctor will use either a CT scan or an MRI (rather than both) to get pictures of the abdomen.

Very young children may be sedated with a general anesthesia to keep them still during the procedure. This means they will be asleep.

Find out more about MRIs.

An x-ray uses small amounts of radiation to make an image of parts of the body on film. If a chest CT scan wasn’t done first, a chest x-ray may be done to check if the cancer has spread to the lungs.

Find out more about x-rays.

In most cases of Wilms tumour, the tumour and the kidney are removed without doing a biopsy first. This is because there is an increased risk that the cancer may spread during a biopsy. The most common surgery used is a nephrectomy, which removes the whole kidney. The surgeon will also remove nearby lymph nodes to stage the cancer and determine the best treatments to give after surgery.

A biopsy of the tumour is done instead of surgery only if:

• the tumour canʼt be removed safely
• the tumour has grown into surrounding tissues, organs and blood vessels
• the child only has one kidney
• there are tumours in both kidneys
• the child appears to have an inherited condition that puts them at risk of a second Wilms tumour
• there is a large blood clot with the tumour
• there is lung disease that may increase the risk of using general anesthesia

Samples collected during surgery or biopsy are tested in a lab. A report from the pathologist will show whether cancer cells are found in the sample.

Find out more about surgery for Wilms tumour and a biopsy.

Chromosomes are the part of cells that hold a personʼs genetic information (DNA) . Tissue removed during surgery may be tested for changes in chromosomes using fluorescence in situ hybridization (FISH). FISH is a laboratory test that looks for losses (deletions) or gains (additions) in parts of chromosomes or in whole chromosomes in the immature kidney cells.

Changes to some chromosomes have been associated with Wilms tumour. These changes can help determine the type of Wilms tumour and what kind of treatment would be best.

Children react to having these tests in different ways. Preparing your child for tests can help. Find more information on helping your child cope with tests and treatments.

To make the decisions that are right for your child, ask the healthcare team questions about diagnosis.