advertisement
|
advertisement |
 |
||||
 |
|
|||
|
||||
|
Acute Lymphocytic Leukemia Tests Acute lymphocytic leukemia (ALL) is often discovered coincidentally during a routine checkup or blood test performed for an unrelated complaint or condition. For other people, leukemia may be diagnosed after symptoms develop. No matter what triggers the evaluation for ALL, it begins with the medical history and physical exam. During the medical history, the doctor will ask you questions about your health, to find clues about whether you might have leukemia. Your doctor will ask about how severe your symptoms are, how often you have them, and how long they last. You should also be prepared to answer questions regarding your history of disease and that of your immediate family. Although leukemia is not inherited, it's possible to inherit a predisposition for developing a genetic mutation associated with leukemia. During the physical exam, the doctor will check for swelling of the lymph nodes, spleen, and liver and listen to your heart and lungs. Your blood pressure and pulse will be measured. Your doctor will look for physical signs of infection and evaluate your skin color and condition. Based on the results of the history and physical exam, your doctor may order additional testing. Despite the sophistication of many testing procedures and the valuable information they can provide, tests alone do not provide a diagnosis. Your doctor is ultimately responsible for interpreting test results, so it's vital that he or she has a good grasp of what each test can and cannot reveal about your condition. Before moving forward with a diagnostic test, especially an invasive test like bone marrow biopsy, review with your doctor how the test results will add to his or her understanding of your condition. This section contains more on: Blood Sampling Blood testing is routinely performed as part of an evaluation for leukemia as well as during treatment and follow-up care. Although they can give clues to the person's health condition, blood samples can not definitively diagnose acute lymphocyte leukemia. Preparing for a blood test usually requires abstaining from food and all beverages with the exception of water for nine to 12 hours prior to the blood draw. Check with your healthcare provider for detailed instructions. During the procedure, samples of peripheral blood are drawn from a vein, usually from the inside of the elbow or the back of the hand using a thin, hollow needle. Bone Marrow Examination During a bone marrow examination, samples of the liquid and solid portions of the bone marrow are collected. The bone marrow biopsy refers to a sample of the solid bone marrow material; a bone marrow aspiration is a sample of the liquid portion of the marrow. Analysis of bone marrow provides a wealth of information about your blood cells that is necessary to diagnose leukemia. The results can also be used to classify the leukemia, direct treatment, and evaluate the effectiveness of treatment. Biopsy and aspiration of bone marrow is an invasive and painful procedure that is usually only performed after the analysis of blood samples. Bone marrow samples are usually collected from the back of the hipbone in an area known as the posterior iliac crest. This procedure is usually performed in a medical center as an outpatient, using conscious sedation. Given through an IV, conscious sedation uses medications to minimize pain and make it less likely that you'll remember the procedure but it also adds on a couple more hours to the procedure in comparison with local anesthesia. Some people may prefer to use a local anesthesia, which reduces the pain of the procedure while involving less preparation and recovery time and fewer potential complications. The bone marrow aspiration begins with the patient lying face down and on his or her side. After the doctor locates the hip bones at the top of the buttocks, the area is disinfected. The doctor inserts a thick hollow needle, about one third the width of a pencil, equipped with a handle on one end to help guide the needle into the bone. The needle is moved through the bone with a twisting motion. This procedure may cause a deep aching pain because the anesthetics are not able to numb the interior of the bones. A syringe is used to extract about 1 teaspoon of liquid bone marrow. If you are awake, the suction may cause a sharp stinging or pulling sensation that stops as soon as the sample is collected. A bone marrow aspiration is usually followed by a bone marrow core biopsy in the same area. After the aspiration needle, the doctor carefully inserts a slightly larger needle farther into the bone marrow to collect a sample of the bone core. The core biopsy is a small solid piece of bone and marrow (about 1/16 inch in diameter and 1/2 inch long) that is removed. After the biopsy needle is removed, the core biopsy is extracted from the needle for examination under a microscope. The aspiration and biopsy usually take only about 30 minutes; but the entire examination may last two hours depending upon the type of anesthetic you receive. After the procedure, pressure will be held against the biopsy site for a few minutes and a pressure dressing applied to reduce bleeding. Recovering from local anesthesia usually requires only 15 to 30 minutes. After that, you can return to normal activities at your discretion. If the procedure was done using IV sedation, you will need to stay at the health center until the sedative wears off. You will not be able to drive home. It may take up to 24 hours to regain full use of your judgment, memory, or response time after IV sedation. At home, the pressure bandage needs to stay on and dry for 24 hours following the procedure. It's not unusual to experience a small amount of bleeding over the first 24 hours or feel pain for a week or so after a bone marrow biopsy and aspiration. However, if any of the following conditions develop, contact your healthcare provider:
• Excessive bleeding—soaks the bandage or doesn't stop with direct pressure Laboratory Tests Blood or bone marrow samples can be analyzed in a number of ways. These may be used as part of diagnosis, to help your doctor plan your treatment, to check how well a treatment is going, or as part of your follow-up care after treatment. This section contains more on these lab tests: Complete blood count (CBC) The CBC is an initial evaluation of the overall health of your peripheral blood. The results of the CBC are not used to diagnose ALL but can help the doctor assess your overall health and decide if you need additional diagnostic testing. If you are already being treated for leukemia, the CBC can help evaluate the effectiveness of treatment. The CBC evaluates the characteristics and amounts of the different blood cells and can indicate the presence of abnormal cells. The fraction of blood consisting of red blood cells is reported as the hematocrit. The mean corpuscular volume (MCV) is a measure of the size of the red blood cells. The number of platelets and the different types of white blood cells (lymphocytes, monocytes, neutrophils, basophils, and eosinophils) are included in the results. As part of the CBC, the lab also looks for abnormal immature blood cells also known as leukemic blast cells. General blood chemistry General blood chemistry is the analysis of the fluid part of blood after the blood cells have been removed. Usually a group of 20 or more chemical tests including electrolyte levels is included in this analysis. Coagulation studies, which determine how long it takes for blood to clot, may also be performed. These results help your doctor understand how well your vital organs, including the heart, liver, kidney, and spleen, are working and to rule out other diseases that could be causing your symptoms. In patients already known to have leukemia, these tests help detect liver or kidney damage caused by the spread of leukemic cells or by the side effects of certain chemotherapy drugs. These tests also help determine if you need treatment to correct low or high blood levels of certain minerals. Conventional microscopic evaluation Blood and bone marrow samples can also be examined visually, through a microscope. This is done to help diagnose leukemia but also later, during treatment or as part of follow-up care after treatment to make sure the leukemia hasn't returned. With a microscope, doctors can evaluate the size, shape, and other characteristics of blood cells and identify immature blood cells, known as blasts. Healthy peripheral blood does not contain any blasts. Doctors can also distinguish acute myeloid leukemia (AML) cells from acute lymphocytic leukemia (ALL) cells using microscopic evaluation. A sample of blood is prepared for microscopic evaluation by spreading a drop of blood into a thin film on a glass slide and letting it dry. Dyes are then applied to color the different types of blood cells so that they are easy to identify using a microscope. The slide is examined using a microscope, the different types of white cells are counted, and the cells are evaluated to characterize any abnormalities in the cells, if present. Examining bone marrow through the microscope can confirm the diagnosis of acute forms of leukemia and track the effectiveness of treatment. A diagnosis of AML or ALL usually means 20 percent or more of the cells in the bone marrow are leukemic blasts. When this value falls below 5 percent and the blood cell counts improve, the treatment is considered effective and the patient in remission. Cytogenetic testing Cytogenetic testing looks for specific abnormalities in the chromosomes of blood cells that are linked to leukemia. The analysis can be performed on peripheral blood or bone marrow. This information helps your doctor predict how your disease will progress and determine the most effective course of treatment. Some types of chromosomal abnormalities are more difficult to treat than others. In a microscopic cytogenetic analysis, the chromosomes are examined during cell division using a microscope. This analysis is primarily used as an initial screening, to see what chromosomes might be abnormal and to help the doctor choose more specific tests. Fluorescent in situ hybridization (FISH) uses special fluorescent proteins to detect or confirm chromosome abnormalities. FISH is a highly sensitive testing technique. It offers the advantage of being able to evaluate many more cells than is possible using a microscope but can only detect a particular abnormality or a specific group of abnormalities. The polymerase chain reaction (PCR) test is a very specialized and sensitive molecular test. PCR is performed on either blood or bone marrow samples to identify leukemia cells based on the cells' genetic abnormalities. This test can find one tumor cell among a million normal cells. It is primarily used to monitor a patient's health during follow-up because it shows how completely the leukemia has been destroyed by treatment and whether a relapse is likely if treatment is stopped. Flow cytometry and immunophenotyping Flow cytometry identifies types of leukemia cells found in samples of blood, based on the chemicals found on the surface of the leukemia cell. Flow cytometry uses laser beams to identify these different chemicals. Flow cytometry is important in classifying acute lymphocytic leukemia (ALL). Immunophenotyping is performed on samples of bone marrow to distinguish and classify the different types of leukemic cells. This test calls for a specialized type of flow cytometry that uses dyes and a conventional microscope. The information collected by this test is used by doctors to select the best treatment for specific subtypes of ALL. Imaging Medical imaging tests are used to assess the condition of the internal organs. These tests may be performed as part of the diagnosis to rule out other conditions that may be causing symptoms, to look for possible signs of leukemia in your internal organ, or to prepare for treatment or as part of follow-up care. Common imaging tests that your doctor may order include: Chest X-ray In a chest X-ray, electromagnetic energy is used to create images of the internal organs and tissues, including bones. A chest X-ray can show the size, shape, position, and condition of the lungs. Chest X-rays are a routine part of an evaluation for leukemia to assess if the lungs have been affected by the leukemia. Getting a chest X-ray doesn't hurt. Before the test, you will need to remove all clothing and jewelry from the waist up. During the X-ray, you will likely be asked to stand against the plate containing the X-ray film and roll your shoulders forward while holding your arms at your sides so they do not interfere with the picture. The radiologist or technician will ask you to take a deep breath and hold it as the X-ray picture is taken. Holding your breath fills your lungs with air and helps your heart and lungs show up more clearly on the film. Although a chest X-ray exposes you to a small amount of radiation, it is less than that experienced in daily living, and the benefits of the image greatly outweigh the slight increase in cancer risk posed by the radiation exposure. However, women who have any chance of being pregnant when the X-ray is taken should tell their doctors, so that special precautions can be taken to minimize the developing fetus's exposure to radiation. Ultrasound of the abdomen Abdominal ultrasound uses the same sound-based technology used by depth finders on boats. Using a small device that looks like a microphone, called a transducer or probe, ultrasound waves are directed into the abdomen. These sound waves bounce back to the probe at different rates, depending upon the tissue encountered in their pathway. The returning sound waves are analyzed by a computer to generate detailed images of the organs in the abdomen. In patients with leukemia, ultrasound may be used to evaluate the condition of the spleen and other internal organs that may have been affected by the disease. No preparation is needed for an abdominal ultrasound. In this procedure, which usually takes one to two hours to complete, a technician applies a watery gel to the abdomen and then slides the transducer across the stomach to scan the abdomen from various angles. Most patients say the procedure is painless, although some report slight discomfort from the pressure of the transducer on the stomach. Abdominal ultrasound has no negative side effects and poses no known risk to the body. Computed tomography (CT) scan of the chest Computed tomography is a specialized imaging technique that uses X-rays collected from many different angles around the body to generate detailed cross-sectional images as well as three-dimensional images of the body's internal structures and organs, including the heart. Ultrafast CT scans are a special type of CT scan that uses X-rays collected at very short intervals for a more detailed evaluation of the heart in motion. CT scans may be used in some leukemia patients to confirm that the leukemia or its treatment has not affected the heart or lungs. The procedure is painless and requires the patient to lie as still as possible on a table that is guided into a machine that resembles an enormous doughnut. The machine, called a gantry, directs small doses of electromagnetic radiation toward the body from various angles. Because different tissues of the body absorb varying amounts of radiation, a computer can analyze the radiation transmitted through the body to reconstruct the images of the internal structures and organs. Chest and abdominal CT scans involve exposure to a dose of radiation that typically exceeds the average background dose of radiation we experience in daily living. For most patients, however, the benefits far outweigh the minor risks associated with exposure to this level of radiation. However, pregnant women may prefer to postpone getting a CT scan until after they've delivered or choose alternative testing procedures. Individuals with pacemakers or internal cardioverter defibrillators who have been advised to avoid MRIs can safely have a CT scan. Echocardiogram Echocardiography relies on the same sound wave-based technology used in prenatal sonograms and depth finders on boats to image the heart in motion. A small device that looks like a microphone, called a transducer or probe, directs ultrasound waves into the chest. The sound waves, which are inaudible to the human ear, travel into the chest and "bounce back" to a receiver, called an echocardiograph. The returning sound waves are analyzed by a computer to generate images that can be viewed on a video screen. Echocardiograms may be performed on some leukemia patients to see if their heart has been affected by the leukemia or its treatment. The information collected by the echocardiograph can be displayed three different ways: The M-mode echocardiogram looks nothing like a heart. This abstract image is used to measure the size of various structures in the heart and the exact thickness of the heart muscle. The 2-D echocardiogram provides snapshots of how well all the parts of the heart are working. These two-dimensional images cut through the heart, analogous to slices from a loaf of bread. The Doppler echocardiogram helps doctors evaluate the blood flow paths through the heart. The "whoosh" sound heard during the procedure is the echocardiograph's interpretation of blood flowing past the heart's various structures. No preparation is needed for the standard transthoracic echocardiogram, which usually takes one to two hours to complete. Electrodes are attached to the chest to monitor the heart's electrical activity during the test. A technician applies a watery gel to the chest and then slides the transducer across the chest to scan the heart from various angles. In some cases, a contrasting agent or dye is injected into a vein to improve the images from the echo. Most patients say that the procedure is painless, although some report slight discomfort from the pressure of the transducer on the chest. Magnetic resonance imaging (MRI) MRIs use strong magnetic fields and high-frequency radio waves to create three-dimensional images and two-dimensional cross sections of the internal organs. The images produced by MRIs are similar to X-ray images but show more detail of the soft tissues of the body and do not involve electromagnetic radiation. MRI may be performed on some leukemia patients to evaluate the condition of the internal organs and look for signs of leukemia. An MRI machine has a large tube that is big enough to accommodate a patient lying down inside. Radio waves and strong magnetic fields are generated inside the shell of the tube and directed toward the body during an MRI scan. The body responds by emitting weak energy signals that are detected by the MRI machine. A computer converts these signals into three-dimensional images of the heart that can be manipulated to show any two-dimensional cross section. An MRI exam is painless and generally lasts between 30 and 60 minutes. Before the test, you must remove all accessories and clothing containing metal, including jewelry, metal fasteners, dentures, wigs, and hearing aids. Metal objects may interfere with the magnetic field of the MRI, affecting the quality of the image. The procedure involves lying on a table that slides into the tube. Movement can blur the images, so it is important to lie still. The space inside the tube is quite narrow, and some patients may feel claustrophobic. Often patients will be offered headphones or earplugs to help block out the loud tapping and thumping sounds made by the MRI machine and to help them relax. There are no known risks from the magnetic fields and radio waves produced by MRI machines. However, people who have pacemakers, cardioverter defibrillators, or other metal-containing objects inside their bodies cannot get MRIs. Also, the effects of magnetic fields on fetuses are not well understood, so getting an MRI may not be advisable for pregnant women. Lumbar Puncture A lumbar puncture, also known as a spinal tap, is performed to collect a small sample of cerebrospinal fluid (CSF). CSF is the fluid that circulates in your spinal column and the base of the skull to protect your brain and spinal column from injury. For patients with acute lymphocytic leukemia (ALL), a sample of CSF is analyzed for signs that the cancer has spread to the spinal column or the brain. In some cases, a lumbar puncture may be used to administer chemotherapy to prevent or treat leukemia that has spread to the spinal column or brain. A lumbar puncture involves inserting a small needle between the bones of the spine in the lower back to collect the sample. The procedure usually lasts about 45 minutes. It is important to lay as still as possible during this somewhat uncomfortable procedure to minimize the risk of side effects or complications. During the procedure, the patient lies on his side with knees drawn up to the chest in the fetal position. The procedure starts with injecting a local anesthetic in the lower spine to lessen the discomfort. The doctor may recommend a general anesthetic for children who might have trouble lying still for the length of the procedure. The doctor will then insert a needle into the spinal column and withdraw a sample of the CSF. The sample will be analyzed in the laboratory to look for leukemia cells, white blood cell count, and signs of infection. After the procedure, the patient is required to lie flat for 20 minutes to one hour. The most common complications are headache and nausea, which can usually be relieved with bed rest. Serious complications of a correctly performed lumbar puncture are rare. The primary risk for patients with leukemia is that blood will leak into the spinal column, which can provide a pathway for leukemia cells to enter the spinal column. For this reason, it is important to seek out an expert in this procedure. |
Use of this Web site constitutes acceptance of our Terms and Conditions of Use and Privacy Policy.
