white blood cell scan

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white blood cell scan

a nuclear scan to identify and localize an area of inflammation or infection. The scan is performed 4 to 24 hours after the white blood cells are separated from blood drawn from the patient, labeled with technetium or indium, and reinjected.

White Blood Cell Scan

Synonym/acronym: Infection scintigraphy, inflammatory scan, labeled autologous leukocytes, labeled leukocyte scan, WBC imaging.

Common use

To assist in identification of abscess, infection, and inflammation of the bone, bowel, wound, and skin.

Area of application

Whole body.

Contrast

IV radionuclide combined with white blood cells.

Description

Because white blood cells (WBCs) naturally accumulate in areas of inflammation, the WBC scan uses radiolabeled WBCs to help determine the site of an acute infection or confirm the presence or absence of infection or inflammation at a suspected site. A gamma camera detects the radiation emitted from the injected radionuclide, and a representative image of the radionuclide distribution is obtained and recorded or stored electronically. Because of its better image resolution and greater specificity for acute infections, the WBC scan has replaced scanning with gallium-67 citrate (Ga-67). Some chronic infections associated with pulmonary disease, however, may be better imaged with Ga-67. The WBC scan is especially helpful in detecting postoperative infection sites and in documenting lack of residual infection after a course of therapy.

This procedure is contraindicated for

  • high alert Patients who are pregnant or suspected of being pregnant, unless the potential benefits of a procedure using radiation far outweigh the risk of radiation exposure to the fetus and mother.

Indications

  • Aid in the diagnosis of infectious or inflammatory diseases
  • Differentiate infectious from noninfectious process
  • Evaluate the effects of treatment
  • Evaluate inflammatory bowel disease (IBD)
  • Evaluate patients with fever of unknown origin
  • Evaluate postsurgical sites and wound infections
  • Evaluate suspected infection of an orthopedic prosthesis
  • Evaluate suspected osteomyelitis

Potential diagnosis

Normal findings

  • No focal localization of the radionuclide, along with some slight localization of the radionuclide within the reticuloendothelial system (liver, spleen, and bone marrow)

Abnormal findings related to

  • Abscess
  • Arthritis
  • Infection
  • Inflammation
  • IBD
  • Osteomyelitis

Critical findings

    N/A

Interfering factors

  • Factors that may impair clear imaging

    • Inability of the patient to cooperate or remain still during the procedure because of age, significant pain, or mental status.
    • Retained barium from a previous radiological procedure, which may inhibit visualization of an abdominal lesion.
    • Metallic objects (e.g., jewelry, body rings) within the examination field, which may inhibit organ visualization and cause unclear images.
    • Other nuclear scans done within 48 hr and Ga-67 scans within 4 wk before the procedure.
    • Lesions smaller than 1 to 2 cm, which may not be detectable.
    • A distended bladder, which may obscure pelvic detail.
  • Other considerations

    • Improper injection of the radionuclide that allows the tracer to seep deep into the muscle tissue produces erroneous hot spots.
    • Patients with a low WBC count may need donor WBCs to complete the radionuclide labeling process; otherwise, Ga-67 scanning should be performed instead.
    • False-negative images may be a result of hemodialysis, hyperglycemia, hyperalimentation, steroid therapy, and antibiotic therapy.
    • The presence of multiple myeloma or thyroid cancer can result in a false-negative scan for bone abnormalities.
    • Consultation with a health-care provider (HCP) should occur before the procedure for radiation safety concerns regarding younger patients or patients who are lactating. Pediatric & Geriatric Imaging Children and geriatric patients are at risk for receiving a higher radiation dose than necessary if settings are not adjusted for their small size. Pediatric Imaging Information on the Image Gently Campaign can be found at the Alliance for Radiation Safety in Pediatric Imaging (www.pedrad.org/associations/5364/ig/).
    • Risks associated with radiation overexposure can result from frequent x-ray or radionuclide procedures. Personnel working in the examination area should wear badges to record their level of radiation exposure.

Nursing Implications and Procedure

Pretest

  • Positively identify the patient using at least two unique identifiers before providing care, treatment, or services.
  • Patient Teaching: Inform the patient this test can assist in assessing for the presence of infection or inflammation.
  • Obtain a history of the patient’s complaints or clinical symptoms, including a list of known allergens, especially allergies or sensitivities to latex, anesthetics, sedatives, or radionuclides.
  • Obtain a history of the patient’s immune system, symptoms, and results of previously performed laboratory tests and diagnostic and surgical procedures.
  • Note any recent procedures that can interfere with test results, including barium examinations.
  • Record the date of the last menstrual period and determine the possibility of pregnancy in perimenopausal women.
  • Obtain a list of the patient’s current medications, including anticoagulant therapy, aspirin and other salicylates, herbs, nutritional supplements, and nutraceuticals (see Effects of Natural Products on Laboratory Values online at DavisPlus). Note the last time and dose of medication taken.
  • Review the procedure with the patient. Address concerns about pain related to the procedure and explain that some pain may be experienced during the test, and there may be moments of discomfort. Reassure the patient that the radionuclide poses no radioactive hazard and rarely produces side effects. Inform the patient that the procedure is performed in a nuclear medicine department by an HCP. It usually takes approximately 1 to 6 hr, and delayed images are needed 24 hr later. The patient may leave the department and return later to undergo delayed imaging.
  • Sensitivity to social and cultural issues, as well as concern for modesty, is important in providing psychological support before, during, and after the procedure.
  • Explain that an IV line may be inserted to allow infusion of IV fluids such as normal saline, anesthetics, sedatives, radionuclides, medications used in the procedure, or emergency medications.
  • Instruct the patient to remove jewelry and other metallic objects from the area to be examined.
  • Note that there are no dietary or medication restrictions prior to the procedure, unless by medical direction.
  • Make sure a written and informed consent has been signed prior to the procedure and before administering any medications.

Intratest

  • Potential complications:
  • Although it is rare, there is the possibility of allergic reaction to the radionuclide. Have emergency equipment and medications readily available. If the patient has a history of allergic reactions to any substance or drug, administer ordered prophylactic steroids or antihistamines before the procedure.

  • Establishing an IV site and injecting radionuclides are invasive procedures. Complications are rare but do include bleeding from the puncture site related to a bleeding disorder, or the effects of natural products and medications known to act as blood thinners; hematoma related to blood leakage into the tissue following needle insertion; infection that might occur if bacteria from the skin surface is introduced at the puncture site; or nerve injury that might occur if the needle strikes a nerve.

  • Observe standard precautions, and follow the general guidelines in Patient Preparation and Specimen Collection. Positively identify the patient.
  • Ensure the patient has removed all external metallic objects prior to the procedure.
  • Administer ordered prophylactic steroids or antihistamines before the procedure if the patient has a history of allergic reactions to any substance or drug.
  • Avoid the use of equipment containing latex if the patient has a history of allergic reaction to latex.
  • Have emergency equipment readily available.
  • Instruct the patient to void prior to the procedure and to change into the gown, robe, and foot coverings provided.
  • Record baseline vital signs, and assess neurological status. Protocols may vary among facilities.
  • Establish an IV fluid line for the injection of saline, anesthetics, sedatives, radionuclides, or emergency medications.
  • Administer sedative to a child or to an uncooperative adult, as ordered.
  • Draw a 50- to 80-mL sample of blood on the day of the test for separating the WBCs from the blood and an in vitro process of labeling with radionuclide.
  • IV radionuclide-labeled autologous WBCs are administered.
  • Images are recorded 1 to 6 hr postinjection depending on the radionuclide used. Delayed images may be required at 24 hr after the injection.
  • Remove the needle or catheter and apply a pressure dressing over the puncture site.
  • Observe/assess the needle/catheter insertion site for bleeding, inflammation, or hematoma formation.
  • If abdominal abscess or infection is suspected, laxatives or enemas may be ordered before delayed imaging.

Post-Test

  • Inform the patient that a report of the results will be made available to the requesting HCP, who will discuss the results with the patient.
  • Unless contraindicated, advise patient to drink increased amounts of fluids for 24 to 48 hr to eliminate the radionuclide from the body. Inform the patient that radionuclide is eliminated from the body within 6 to 24 hr.
  • No other radionuclide tests should be scheduled for 24 to 48 hr after this procedure.
  • Observe/assess the needle/catheter insertion site for bleeding, inflammation, or hematoma formation.
  • Instruct the patient in the care and assessment of the injection site.
  • If a woman who is breastfeeding must have a nuclear scan, she should not breastfeed the infant until the radionuclide has been eliminated. This could take as long as 3 days. She should be instructed to express the milk and discard it during the 3-day period to prevent cessation of milk production.
  • Instruct the patient to immediately flush the toilet and to meticulously wash hands with soap and water after each voiding for 24 hr after the procedure.
  • Instruct all caregivers to wear gloves when discarding urine for 24 hr after the procedure. Wash gloved hands with soap and water before removing gloves. Then wash hands after the gloves are removed.
  • Recognize anxiety related to test results, and be supportive of perceived loss of independent function. Discuss the implications of abnormal test results on the patient’s lifestyle. Provide teaching and information regarding the clinical implications of the test results, as appropriate.
  • Reinforce information given by the patient’s HCP regarding further testing, treatment, or referral to another HCP. Answer any questions or address any concerns voiced by the patient or family.
  • Depending on the results of this procedure, additional testing may be needed to evaluate or monitor progression of the disease process and determine the need for a change in therapy. Evaluate test results in relation to the patient’s symptoms and other tests performed.

Related Monographs

  • Related tests include angiography pulmonary, bone scan, colonoscopy, CBC, CBC WBC count and differential, CT abdomen, CT pelvis, CT spine, culture (blood, skin, wound), ESR, fecal analysis, gallium scan, GI blood loss scan, KUB, MRI musculoskeletal, MRI pelvis, MRI spine, proctosigmoidoscopy, radiography bone, US abdomen, US pelvis, and vitamin D.
  • Refer to the Immune System table at the end of the book for related tests by body system.