Tests and procedures to diagnose cancer
WHICH TESTS MIGHT UNDERGO MY CHILD
Here are brief descriptions of some of the tests that might be done during diagnosis and treatment. A child does not have every one of these tests.
Some drugs can affect hearing. Baseline hearing tests (audiology) and regular testing during treatment are done with children receiving these drugs.
If it is suspected that a tumour is malignant (cancerous), the surgeon may first remove a part of it, either by inserting a small needle through the skin (needle biopsy) or by doing a small operation (open biopsy). A CT guided biopsy may also be done by a radiologist. The whole tumour may be removed at the initial surgical procedure. This specimen is then examined by a specialist doctor – a histopathologist – who can tell whether or not it is malignant and exactly what type of tumour it is. It usually takes a few days to get the results. Sometimes specialised tests such as chromosome analysis or special staining tests to look more closely at the tumour tissue may be required to help with the diagnosis. The type of biopsy done depends on the individual child’s specific clinical circumstances.
Blood tests are done at the time of diagnosis, during treatment and occasionally after treatment, to monitor the effects of treatment. The blood cells re counted in the haematology department. The blood count is one of several different ways to monitor the effects of treatment. Your child’s doctor can tell you what your child’s blood counts are, what this means and what they are expected to be. Microbiologists may check the blood to see whether there is infection. This is called a blood culture. The chemistry laboratory measures certain salts and chemicals in the blood sample. This gives information about kidney and liver function. Blood samples may also be obtained to cross-match blood in case a transfusion is needed. A short video, ‘Blood counts explained’ is on the PICS website.
Bone marrow aspirate
The bone marrow is like a factory where the blood cells in the body are produced. In children, bone marrow is in the long bones, ribs, pelvis and hips. To see whether the cancer has affected the bone marrow it is necessary to obtain a sample. This is done by placing a fine needle into the bone in the hip and taking out a small amount of the marrow which is then examined in the laboratory. Occasionally a core of marrow (trephine biopsy) is required to examine the marrow in more detail. Bone marrow aspirate is generally performed under a general anaesthetic.
A bone scan is done in the nuclear medicine department to get an image of a bone or bones, to see if there is any cancer present. The scan itself is not painful, however an injection of radioactive material (an isotope) is given first and then a scan performed a couple of hours later. Where there is increased cell activity the isotope will accumulate and become visible on the scan.
Computerised Axial Tomography – also called a CAT scan – takes many pictures of soft tissue inside the body, from different directions. A computer integrates the pictures to show any tumours. Scanning is painless but a needle is sometimes required to inject contrast. A CT scan usually takes less than five minutes. A sedative or a general anaesthetic may be needed to ensure that the child stays still for this time.
Central Venous Access Device. See Port, Hickman, Insuflon or Portacath.
An ultrasound test is used to assess heart function. Some chemotherapy drugs have the potential to affect heart function. Heart function is monitored at regular intervals when these drugs are used.
This records the rate, rhythm and electrical activity of the heart.
Gallium scans are done in the nuclear medicine department. Before the scan, an injection of Gallium is given. Gallium gathers at sites of infection or malignancy. The first scan is usually done 48 hours after the injection and a second scan is done a week later.
Glomerular Filtration Rate (GFR)
Some drugs have the potential to affect kidney function. Children having these drugs have their kidney function monitored regularly during treatment. Glomerular Filtration Rate (GFR) is a very specialised nuclear medicine test of kidney function. Two blood samples are taken on the day to measure kidney function.
With some cancers, such as leukaemia or lymphoma, malignant cells can pass into the brain and cerebrospinal fluid surrounding the brain. To find out whether this has occurred, a few drops of the fluid are removed by inserting a fine needle between two vertebral bones in the spine.
Magnetic Resonance Imaging (MRI) scan
Magnetic waves are passed through the body and produce different images depending on the type of cell they pass through. They are harmless. The MRI can give an accurate picture of a tumour and the surrounding structures.
Sometimes in CT, MRI and X-ray a special fluid called ‘contrast’ is injected into the blood to get a better picture of the tumour and its relationship to other structures.
The MRI machine is noisy and may be scary because the child has to lie in a tunnel. Different hospitals may use different ways to help children learn about the MRI scan procedure and prepare them to stay calm and still during the scan. Please speak to your child’s treating team about the facilities available at your child’s treating hospital. Although having the MRI is painless, a general anaesthetic may be required to keep the child still.
PET Scan – Positron Emission Tomography – gives a picture of how a part of the body is working. A small amount of radioactive chemical is injected or breathed in. The PET scan shows where this chemical goes. PET Scans can help identify malignant and benign tumours.
Ultrasound waves are sound waves that the human ear cannot hear. A special machine directs the waves at a certain part of the body. Differences in how the sound waves are reflected helps form an image. This is interpreted to distinguish a healthy part from a tumour.
An x-ray can show whether there is tumour in the chest, abdomen or bones because tumour tissue looks different from ordinary bone or normal tissue. X-rays can also be taken to look for signs of infection if your child is unwell.
WHICH PROCEDURES MIGHT BE PART OF THE TREATMENT
Procedures are done by nurses and doctors as part of a child’s treatment – like putting in an IV or a nasogastric tube or accessing a port. A child does not have every one of these procedures. Some procedures are done with sedation or general anaesthesia. Some of the devices used during procedures are:
These are tubes put into a large central vein to give fluids and chemotherapy. Blood samples can sometimes be taken from them. They are semi-permanent and can stay in place for several months or years and are put in under general anaesthetic. There are different types – Port-a-caths, PICCs, Hickmans. Your nurse will give you more information if your child needs a central line.
Several drugs may be given under the skin by subcutaneous injection. When a drug needs to be injected several times, we use a small device called an Insuflon. This reduces the pain and worry of daily injections. The Insuflon is inserted under the skin and can stay there for up to seven days. It can be inserted into the skin of the abdomen, thigh or upper arm. The Insuflon allows drugs to be administered without the need for repeated injections. Either you, your child, or your nurse can administer the injections using the Insuflon.
With the Insuflon in place your child can continue with activities of normal daily living, including bathing and swimming. At home the Insuflon site should be checked regularly for signs of swelling, redness, and/or discharge. If you notice any of these signs, or should the Insuflon accidentally be removed please contact your hospital team.
A nasogastric tube goes from the nose into the stomach. It is used to give liquids including nutrition and medicine. If your child needs a nasogastric tube, the nurses will give you more details.
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