Leukemia can be diagnosed with a variety of tests, and understanding what each test is and what it looks for can make the tests a little less confusing. Remember to let friends and family be a source of support during the stressful time of testing and diagnosis, whether it is you who are the patient or your child. While some tests are more definitive than others, usually a doctor uses the results from a variety of exams, lab results, and scans to diagnose the specific type of leukemia, how advanced it is, and what type of treatment is recommended. Some important questions to ask before any test are:
- What will this test tell us?
- How is this test done?
- When will we get the results?
- What is the next step after we get the results of this test?
Physical Examination
An exam is much like any doctor's appointment; the doctor will take a detailed medical history and thoroughly examine the whole body. In addition to the standard check of vital signs and breath sounds, the doctor will examine the lymph nodes in the neck and armpits to look for swelling caused by large amounts of white blood cells gathered in the lymph nodes. The doctor will also press on the abdomen (stomach area), noting any tenderness or swelling which would suggest that a large concentration of leukemic white blood cells is enlarging the spleen. A physical exam doesn't usually cause any any side effects, except for the normal worry about a possible leukemia diagnosis.
Blood Tests
Blood tests are chemical tests done on a sample of blood in a laboratory. A sample of blood is taken from a patient's vein with a needle and collected in a vial, then sent to a laboratory to be analyzed. The most common blood test for leukemia is the complete blood count, or CBC. A CBC counts the number of white blood cells, red blood cells, and platelets in a blood sample. A sample of blood with high numbers of white blood cells and low levels of red blood cells or platelets can indicate leukemia, and abnormal liver and kidney function tests will tell the doctor if leukemia has affected those organs.One very important test that allows doctors to look specifically for blasts in a blood sample is flow cytometry. Flow cytometry also allows doctors to examine the physical characteristics of the blasts, allowing for more precise diagnosis. Blood draws should only be felt as a quick pinch, so don't be afraid to ask for someone else if the person drawing the sample is having trouble finding a vein.
Bone Marrow Biopsy
A biopsy takes a small sample of bone marrow tissue from the body. A bone marrow biopsy or aspiration is done in in the doctor's office. The doctor asks the patient to lie on his or her side and nurses clean the biopsy site with iodine or alcohol. After the site is cleaned, the biopsy site is numbed with a local anesthetic. The doctor uses either a very fine needle to draw out only bone marrow tissue, or a thicker needle to take a small sample of bone and bone marrow. The bone marrow sample is examined under a microscope to check for leukemia cells. This procedure should be relatively painless, as a local anesthetic such as lidocaine will be used, and the inside of the bone has no nerve endings. Patients may request light sedation and narcotics during the procedure. There may be some soreness after the procedure, so it's important to take it easy and follow the doctor's instructions for taking care of the biopsy site.Cytogenetics
Cytogenetics is a newer type of testing for leukemia, and it looks at the chromosomes in individual cells. Cytogenetic testing uses a sample taken from a blood draw or a bone marrow or lymph node biopsy. The sample's chromosomes are microscopically examined for abnormalities that indicate damage to the cells' DNA.
Spinal Taps
A spinal tap involves a doctor taking a sample of cerebrospinal fluid. The samples is usually taken from the lower back (the lumbar area). Spinal taps take place in a procedure room in a doctor's office, and the patient is asked to lie on his or her side. The doctor then cleans the site of the puncture and injects a local anesthetic to numb the area. A special needle called a spinal needle is inserted into the space between vertebrae, and cerebrospinal fluid is drawn through the needle and into a collection tube for analysis. The fluid sample is then checked for leukemia cells and other abnormalities. A spinal tap can cause a severe headache that lasts a long time if the patient moves around too quickly after the procedure. There may also be some small discomfort at the site of the puncture, and as always, it's important to follow any instructions given by the doctor after the spinal tap.
Scans and X-rays
MRIs (Magnetic Resonance Imaging), CT (Computerized Axial Tomography) scans, and x-rays are all technologies that use various machines to take pictures of bones, organs, and tissues inside the body. In the case of CT scans and MRIs, the technician has the patient lie down on a table that moves into a tube. CTs and MRIs build detailed 3-D pictures that can be examined by the doctor from any angle. In an x-ray, a patient is positioned so that two-dimensional pictures can be taken of the body. These images are interpreted by a radiologist and the images and a written report are sent back to the doctor. Scans and x-rays allow doctors to visually pinpoint problem areas within the body, and locate areas of infection.
Sources:
"What You Need to Know About Leukemia." National Cancer Institute. 31 Mar 2003. National Institute of Health. 20 Feb 2008.
"How Childhood Leukemia is Diagnosed." 19 Aug 2007. American Cancer Society. 20 Feb 2008.
