Laboratory Procedures

Arterial Blood Gas (ABG). Blood test measures the amounts of oxygen and carbon dioxide in the blood, as well as the acidity (pH) of the blood. A blood sample is taken from an artery, usually in the wrist. It is normal to feel a sharp stick momentarily when the technician or nurse inserts the needle. Pressure must be applied to this area for a short time afterward to prevent bleeding. This test provides important information about how effectively the lungs are delivering oxygen to the blood and how efficiently they are eliminating carbon dioxide from it. The test also indicates how well the lungs and kidneys are interacting to maintain normal blood pH.

Bone Marrow Aspiration or Biopsy. A small amount of bone marrow, usually from the back of the hip, is collected to determine how the bone marrow is functioning. Before insertion of the bone marrow aspiration needle, the aspiration site is numbed with local anesthesia. Most people feel pressure as the needle is inserted and a few seconds of pain when the bone marrow fluid is withdrawn. With a bone marrow biopsy a small piece of bone is removed. A biopsy may be slightly more painful, but only during the time that the procedure is being done.

Bone Scan.   An imaging test that creates pictures of the bones on a computer screen or on film. A small amount of radioactive material is injected into a blood vessel and travels through the bloodstream; it collects in the bones and is detected by a scanner.  During the scan, which usually takes about an hour, the patient lies on his or her back on a table, but may be repositioned to the stomach or side during the study. It is important for the patient not to move, except when directed to by the technologist.

Chest X-Ray.   An x-ray of the structures inside the chest. An x-ray is a type of high-energy radiation that can go through the body and onto film, showing areas inside the chest, the condition of the lungs and if the patient has pneumonia.  Chest x-rays can be taken at the bedside or in the Diagnostic Imaging department. A hard plate containing film is placed behind the back.  During the actual time of exposure, the technologist will ask the patient to hold his or her breath. It is very important in taking a chest x ray to ensure there is no motion that could ruin the quality and sharpness of the film image. The procedure takes just a few minutes and the time patients must hold their breath is a matter of a few seconds.  This test is routine for all BMT patients. Other x-rays – abdominal, sinus or pelvis – may be done as well. The procedure is basically the same for each type of x-ray.

Computed Tomography (CT) Scan.  A type of three-dimensional x-ray used to view various body structures; also known as a computerized tomography scan or a computerized axial tomography (CAT) scan. This may be done with or without contrast dye, which is a fluid injected into the bloodstream to aid in the examination of the x-ray.

If a contrast dye has been ordered, a series of pictures taken, then a small amount of contrast dye injected is injected, followed by a second pictures.  If no contrast dye was ordered, only one set of pictures taken. The procedure is painless and the time varies depending on which part or parts of the body are scanned.

Dialysis.   A method of removing impurities or waste products (toxins) from the blood when the kidneys are unable to do so. There are different ways of doing dialysis:
Hemodialysis uses a special type of filter to remove excess waste products and water from the body.  Blood leaves the body through a tube in an artery, and then passes through a filter in the dialysis machine (dialysis or semipermeable membrane).  A solution (dialysate) on the other side of the membrane receives waste products from the blood, then the clean blood is returned to the body through a vein.

CAVH and CVVH (see glossary) are other methods by which dialysis is performed continuously through access in an artery and vein.

Peritoneal dialysis uses the lining of the abdomen as a blood filter. A catheter placed into the abdomen is used to fill the abdominal cavity with dialysate. Waste products and excess fluids move from the patient’s bloodstream into the dialysate solution. After a waiting period, the waste-filled dialysate is drained from the abdomen, and replaced with clean dialysate.

Electrocardiogram (ECG or EKG). The patient disrobes from the waist up, and electrodes (tiny wires in adhesive pads) are applied to specific sites on the arms, legs, and chest.  The wires are attached to a machine that records the electrical activity of the heart onto a paper strip. The process takes only a few minutes and is painless.

Gallium Scan. A nuclear medicine test, which uses a special camera that detects gallium, a radioactive chemical substance known to accumulate in inflamed, infected, or cancerous tissues.  An injection of gallium is given in advance of the scan, usually 24-48 hours; the timeframe is based on the area or organs of the body being studied.  For the study itself, the patient lies very still for approximately 30-60 minutes. A camera is moved across the patient’s body to detect and capture images of concentrations of the gallium.  The camera may occasionally touch the patient’s skin, but will not cause any discomfort. A clicking noise may be heard throughout the procedure.

Lumbar Puncture (LP).  A procedure where a sterile needle is introduced into the lower spine to collect cerebrospinal fluid (CSF) for diagnostic purposes.  The patient is typically lying down sideways for the procedure. Less often, the procedure is performed while the patient is sitting up. After local anesthesia is injected into the small of the back (the lumbar area), a needle is usually inserted in between the 3rd and 4th lumbar vertebrae into the spinal canal. Headaches, which are not uncommon after LP, occur less frequently when the patient remains lying flat 1-3 hours after the procedure.

Magnetic Resonance Imaging (MRI). A procedure that uses radio waves and a powerful magnet linked to a computer to create detailed pictures of areas inside the body. These pictures can show the difference between normal and diseased tissue. MRI makes better images of organs and soft tissue than other scanning techniques, such as CT or x-ray. MRI is especially useful for imaging the brain, spine, the soft tissue of joints, and the inside of bones. After a series of pictures are taken, contrast dye may be injected into a vein, followed by another set of pictures.  The machine produces loud thumping and humming noises during normal operation. An MRI is painless and has the advantage of avoiding x-ray radiation exposure, but some patients may feel claustrophobic from being inside the scanner.  People with pacemakers or other metal objects implanted into their bodies should NOT have an MRI.

Multiple-gated Acquisition (Muga) Scan.   A non-invasive test that measures the function of the heart by using radioactive tracers to make heart chambers and blood vessels visible. Instruments do not touch the heart structures.  Electrodes may be placed on the chest. An intravenous line will be placed into the arm to inject the radioactive isotope, then a camera or scanner will be placed over the chest area to process the images. The scan may be repeated during exercise on a treadmill or stationary bicycle.

Pulmonary Function Tests (PFTs).  A broad range of tests that measure how well the lungs take in air (lung volume measurement), exhale air (spirometry) and how efficiently they transfer oxygen into the blood (diffusion capacity).  Routinely done before a BMT, these painless breathing tests take approximately 60 to 90 minutes.

Total Body Irradiation (TBI).  Radiation is delivered to the entire body to kill any diseased cells or bone marrow. Treatment is given in the Division of Radiation Medicine and takes approximately 45 minutes per session.

Ultrasound. A noninvasive test that uses high- frequency sound waves to produce images of the organs and structures of the body. A clear, water-based gel that helps transmit sound waves is applied to the skin over the area being examined. The sound waves are sent through body tissues with a probe (a transducer) that is placed on the skin, then reflected by internal structures as “echoes.” These echoes return to the transducer and are transmitted electrically onto a viewing monitor, then recorded on a film or on videotape. Ultrasound testing is painless and harmless.

24-hour Urine Collection. A 24-hour specimen collection of urine used to determine kidney function.  To collect a 24-hour urine:

  • On day 1, urinate into the toilet upon arising in the morning.
  • Collect all urine (in a special container) for the next 24 hours.
  • On day 2, urinate into the container in the morning upon arising.
  • Cap the container.  Keep it in the refrigerator or a cool place during the collection period.  Label the container with your name, the date, the time of completion, and return it as instructed.