Diagnostic Tests and Specimen Collection
Diagnostic Testing and the Nursing Process
Planning
Diagnostic Tests
Laboratory Tests
Hematology Tests
* Complete blood count (CBC)
o Information about the state of health or presence of illness
o Number of red blood cells (erythrocytes)
o Type and number of white blood cells (differential)
o Platelet count, PT, PTT, INR
* During infection, the number and type of white blood cells increase.
* Neutrophil counts can be significant.
* In severe infections, bone marrow releases more granulocytes.
* Immature polymorphonuclear neutrophils are released (called bands).
* The result is a shift to the left (more bands).
* Drug therapy may cause leukopenia (a decrease in leukocytes).
* Hemoglobin shows the capacity of the blood to transport oxygen from the lungs to the tissues.
* A normal platelet count is essential to clotting.
* Coumadin therapy is guided by prothrombin time (reported in INR numbers).
* The erythrocyte sedimentation rate (ESR) gives clues about inflammatory conditions.
Chemistry Tests
* Whole blood, plasma, and serum
* Body fluids such as:
o Urine, spinal fluid, gastric contents
* Chemistry tests provide information about biochemical reactions such as electrolyte balances and organ function.
* Some institutions use automated computerized blood chemistry testing.
* Examples of tests available are:
o Serum albumin, alkaline phosphatase (ALP), aspartate aminotransferase (AST)
o Total bilirubin, serum calcium, cholesterol, glucose, LDH, phosphate, total protein, BUN, uric acid
Blood Glucose
* Blood glucose is a test commonly performed at the bedside or in the physician’s office by the nurse.
* Guides insulin therapy for diabetics
* Guidelines for performing test depend on manufacturer of testing equipment
* Requires a finger stick to obtain capillary blood
Serology Tests
* Based on analysis of serum
* Used to diagnose both viral and bacterial diseases or determine antibody levels for:
o Dysentery, rheumatic fever, typhoid, influenza, rubella, and syphilis
* Can also be used to determine titers in response to vaccines
* May use radionuclides such as iodine-125 and iodine-131
* Examples of serology tests ordered
* Agglutination test for specific organisms
* Antistreptolysin-O titer
* Blood typing: ABO groups and Rh
* Carcinoembryonic antigen assay (CEA)
* Coombs’ test
* C-reactive protein antiserum
* Heterophil antibody titer
* Tests for syphillis
Urinalysis
* Provides information about kidney function or other body functions and diseases
* Single, catheterized, or random specimens can be collected anytime, with no special preparation. First voided specimen is preferred.
* Urine deteriorates quickly and should be tested soon after collection.
Midstream collections
* External genitalia are cleansed
* A small amount of urine is passed.
* Urine is collected from midvoiding in a sterile container.
* Used for cultures when a bladder infection is suspected
Timed, long-period specimens
* Collected over 12- or 24-hour period
* Container may be kept on ice and has some form of preservative.
* Used to determine kidney function and possible glomerulonephritis or acute tubular necrosis
Other Laboratory Tests
* Bacteriology
* Histology
* Cytology
* Ova and parasites
* Cultures from specimens of feces, blood, urine, wound drainage, or samples of body tissue or fluids
Ultrasonography
* Records the reflection of sound wave directed into the tissues
* Used to diagnose pathologic conditions of
o Uterus, ovaries, prostate, heart, liver, kidneys, pancreas, gallbladder, lymph nodes, thyroid, eyes, and peripheral blood vessels
* Often used in conjunction with nuclear medicine scans
Radiology Procedures
* Most common test is radiation by x-ray
* Produces images in varying densities on film after it passes through the body
* Commonly performed radiology procedures:
o Chest x-ray
o Barium swallow and upper GI series
o KUB (kidneys, ureters, and bladder)
o Gallbladder series
* IVP (intravenous pyelogram)
* X-ray of bony skeleton
* Arthrogram
* Myelogram
* Radionuclide scan
* Computed tomography (CT) scan
Magnetic Resonance Imaging
* Noninvasive method of differentiating body tissue (commonly used for brain, knee joint, spine and spinal cord, and abdominal organs)
* Requires that all metal be removed from the patient
* Contraindicated in patients with hip prostheses, implanted pacemakers or defibrillators, artificial cardiac valves, or vascular clips or staples from recent surgery
* Patient teaching is very important before this procedure; patient needs to know the duration of the test and that it requires being in a noisy environment.
* Patient may become claustrophobic during test.
* Patient needs to know deep-breathing and relaxation techniques.
Cardiopulmonary Studies
EKG/ECG
* Diagnoses heart rhythms and heart disease; measures electrical activity of the heart
Cardiac catheterization
* An invasive procedure used to determine function of heart valves, coronary artery blood flow, and oxygenation at different points in the heart and to diagnose coronary artery disease
o Abnormal blood in cardiac vessels can be detected as can valvular dysfunction.
* Surgical procedure that requires consent
* Procedure is performed under sterile technique in radiology or a surgical suite.
* Postprocedure requires checking insertion site every 10 to 15 minutes for possible bleeding.
* If the femoral approach is used, the patient’s leg may be immobilized for several hours.
* New angioseal devices may preclude the need for post procedure pressure.
Treadmill Stress Test
* A cardiac-monitored ECG test
* Patient is on a treadmill, which is used to increase heart rate and blood pressure with controlled activity.
* Test may be done with radioisotope imaging
* Patient should avoid smoking, dairy products, or drinking caffeine for 4 hours before the test.
* Angiography/Arteriography
* Used to locate lesions, occluded vessels, tumors, and malformed blood vessels
* A contrast medium is injected during the procedure (check for allergies).
* Consent is required.
* Patient should be NPO for at least 6 hours before the test.
* Patient may be given preprocedure sedation.
Other Tests
* Endoscopic examinations of:
o The stomach (gastroscopy)
o The sigmoid colon (proctosigmoidoscopy)
o The entire colon (colonoscopy)
o The bladder (cystoscopy)
o The gallbladder and common bile duct (endoscopic retrograde cholangiopancreatograhy [ERCP])
Electroencephalography (EEG)
* Measures neurologic and physiologic activities of the brain via the electrical discharges from the brain
* Performed to localize and diagnose brain lesions, scars, epilepsy, infections, or clots
* Performed to determine brain death in comatose patients on life support
Things to Remember
* All invasive tests requiring injection of a medium require a consent.
* Tests requiring premedication or sedation usually require a consent.
* Many tests have some form of preparation; review the laboratory manual for your facility to determine what must be done before the patient has the test and after the patient has had the test.
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