Chapter 25: Diagnostic Tests
CHAPTER 25: Diagnostic Tests
KEY TERMS
Arteriography (ar-TEER-ee-AWG-ruh-fee): A diagnostic imaging technique that uses X-rays to visualize the inside of blood vessels and organs of the body through the injection of a contrast medium.
Barium enema (BA-ree-um EN-e-muh): A procedure used to visualize the lower gastrointestinal tract, wherein a barium sulfate suspension is introduced into the rectum and X-ray imaging is performed.
Bone marrow aspiration (BOWN MA-roh ASS-pi-RAY-shun): A procedure to extract bone marrow from the pelvic bone or other sites to diagnose conditions such as blood disorders and cancers.
Chest x-ray (CHEST EKS-ray): An imaging test that produces pictures of the chest, including lungs, heart, and bones, to identify conditions such as infections, tumors, and chronic lung diseases.
Colonoscopy (KOH-lun-AWS-kuh-pee): A minimally invasive procedure that examines the colon and rectum using a flexible tube with a camera, commonly used for colorectal cancer screening.
Complete blood cell count (kom-PLEET BLUHD SELL KOWNT): A laboratory test that measures the components of blood, including red blood cells, white blood cells, hemoglobin, hematocrit, and platelets to assess overall health and detect disorders.
Complete metabolic panel (kom-PLEET MET-uh-BAH-lik PAN-uhl): A group of blood tests used to evaluate metabolic functions and assess kidney and liver health along with electrolyte balance.
Computed tomography (kom-PEW-ted toh-MAWG-ruh-fee): An advanced imaging technique that combines X-rays and computer technology to produce cross-sectional images of the body for critical diagnosis.
Differential (dif-uh-REN-shul): A component of the complete blood count that measures the percentage of different types of white blood cells, providing insights into immune system function and possible infections.
Echocardiogram (EK-oh-KAR-dee-oh-GRAM): An ultrasound test that examines heart structures and function, helping to diagnose various heart conditions.
Electrocardiography (ee-LEK-troh-KAR-dee-AWG-ruh-fee): A test that records the electrical activity of the heart over a period using electrodes placed on the skin, crucial for diagnosing arrhythmias and other heart diseases.
Electroencephalography (ee-LEK-troh-en-SEF-uh-LAWG-ruh-fee): A monitoring method used to record electrical activity in the brain and diagnose conditions such as epilepsy and sleep disorders.
Esophagogastroduodenoscopy (eh-SOF-ah-goh-GAS-troh-doo-AW-den-AWS-kuh-pee): An endoscopic procedure used to examine the upper digestive tract and assess conditions like GERD or tumors.
Glomerular filtration rate (gloh-MER-yoo-ler fill-TRAY-shun RAYT): A test that measures the rate at which the kidneys filter blood, serving as a critical marker for kidney health.
Glycosylated hemoglobin (GLY-koh-sye-LAY-tuhd HEE-muh-GLOW-bin): An important blood test that provides an average blood glucose level over a period, assisting in the management of diabetes.
Intravenous pyelogram (IN-trah-VEE-nus PIE-eh-lo-GRAM): An X-ray examination of the kidneys and urinary tract where a contrast dye is injected into a vein.
KUB: A radiological examination of the Kidneys, Ureters, and Bladder, typically performed to assess the urinary system.
Left shift (LEFT SHIFT): A clinical term indicating an increased proportion of immature neutrophils in the blood, commonly observed in bacterial infections.
Lumbar puncture (LUM-bar PUNK-chur): A medical procedure performed to collect cerebrospinal fluid for diagnosis of neurological conditions and infections.
Magnetic resonance imaging (mag-NET-ik REZ-uh-nanss IM-uh-jing): A non-invasive imaging technology that employs magnetic fields and radio waves to visualize internal structures without ionizing radiation.
Oral glucose tolerance test (OR-uhl GLOO-kohss TALL-er-ens TEST): A test that assesses how the body processes glucose, commonly used to diagnose diabetes.
Paracentesis (PAR-ah-sen-TEE-siss): A procedure to remove fluid from the abdominal cavity for diagnostic purposes or relief of pressure.
Right shift (RIGHT SHIFT): A condition indicating an increase in mature lymphocytes, which may signify viral infections or chronic inflammatory conditions.
Thoracentesis (THOR-uh-sen-TEE-siss): A procedure to remove fluid from the space between the lungs and chest wall, primarily performed for diagnostic and therapeutic purposes.
Ultrasonography (UHL-truh-son-AWG-ruh-fee): An imaging technique using high-frequency sound waves to visualize soft tissues and organs, often used in pregnancy and organ assessments.
Venography (vee-NAWG-ruh-fee): An imaging test to visualize the veins, often with the use of contrast dye to detect blood clots or other vascular problems.
CHAPTER CONCEPTS
LEARNING OUTCOMES
Define various terms associated with diagnostic tests, including distinguishing between different imaging modalities and their specific clinical applications.
Explain the nurse's role and responsibilities regarding preparation for tests (e.g., obtaining informed consent, assessing allergies) and post-test nursing care (e.g., monitoring vital signs, assessing for complications).
Discuss all components of a complete blood cell count, including normal ranges for each component (e.g., WBCs: 4,500–11,000 cells/mcL).
Identify the components of a white cell count with differential, including possible causes for abnormal values (e.g., increased neutrophils indicating infection).
Explain components of blood chemistry testing (e.g., liver enzymes, electrolytes) and their significance in diagnosing various medical conditions.
Determine the purposes of testing cardiac enzymes (e.g., troponin, creatine kinase), B-type natriuretic peptide, lipase, and glycosylated hemoglobin, focusing on their clinical implications.
Contrast normal and abnormal findings of urinalysis and their significance, including potential implications for renal and diabetic conditions.
Explain how the glomerular filtration rate is determined and its significance as a cornerstone in assessing renal function.
Describe radiology and imaging tests, including computed tomography and magnetic resonance imaging, detailing the various nursing care associated with each (e.g., pre-procedural checks, patient education).
Discuss arteriography, venography, computed tomography angiography, and magnetic resonance angiography, including nursing care steps such as contrast monitoring and post-procedure assessment.
Explain preparation for, purpose of, and nursing care after endoscopic exams, emphasizing the risk of sedation and potential complications.
Identify allergies that the nurse should assess prior to procedures and tests requiring contrast medium to prevent adverse reactions.
Discuss purposes of graphic recording tests including telemetry, emphasizing the nursing care required to ensure accurate data collection.
Explain purposes for lumbar puncture, bone marrow aspiration, paracentesis, and thoracentesis, focusing on patient positioning for each procedure and reasons for careful technique.
Discuss Connection features in this chapter, highlighting interdisciplinary collaboration in patient care.
Identify specific safety information relevant to diagnostic testing to ensure patient protection and procedural efficacy.
Answer questions regarding the skills in this chapter, preparing students for practical application in clinical settings.
SKILLS
25.1 Assisting With Aspiration Procedures: Bone Marrow, Lumbar Puncture, Paracentesis, and Thoracentesis
25.2 Performing a 12-Lead Electrocardiogram
PATIENT-CENTERED CARE
CRITICAL THINKING CONNECTION
Clinical Assignment: A 37-year-old female hospitalized with abdominal pain, nausea, and vomiting has been ordered an esophagogastroduodenoscopy, and ultrasound of the gallbladder and pancreas, and blood work including blood chemistry, electrolyte panel, alkaline phosphatase, GFR, and creatinine. Evaluate her medical history, presenting symptoms, and potential diagnoses during your assessment.
Responsibilities
Preparation: Explain the tests clearly, alleviate fears regarding needles and procedures, and provide reassurance throughout the diagnostic experience.
Post-Test Assessment: Monitor for signs of adverse effects from the tests such as bleeding, infection, or complications due to sedation.
Significance of Normal Ranges: Knowing normal ranges allows for appropriate notification to healthcare providers if abnormalities are detected, improving patient outcomes.
DEFINITION OF DIAGNOSTIC TESTS
Diagnostic tests are examinations that assist in forming a medical diagnosis by ruling out or confirming diseases or injuries. These are routine tests commonly encountered in healthcare settings that provide crucial information for treatment planning.
NURSING'S ROLE IN DIAGNOSTIC TESTING
Responsibilities
Responsibilities before the test include:
Note the healthcare provider's order for accuracy in testing.
Schedule the test or procedure based on urgency and hospital protocols.
Educate the patient on the process, addressing their questions and concerns to minimize anxiety.
Ensure the patient’s safety by checking for allergies to dyes or preparations involved in tests that may cause adverse reactions.
Administer laxatives/enemas for better visualization during imaging tests, as per the test requirements.
Obtain informed consent (ensuring the provider explains the test fully).
Know dietary restrictions (e.g., ensuring patients are NPO as required).
Prepare the patient mentally and physically for the procedure.
Assist the examiner during the test, ensuring the environment is safe and conducive to accurate results.
Responsibilities after the test include:
Obtain or deliver specimens to the laboratory promptly, maintaining specimen integrity.
Monitor the patient's condition post-test for any immediate reactions or complications.
Support and reassure the patient, offering comfort measures as needed.
Notify healthcare providers of significant abnormal results that could alter patient management.
Watch for complications and provide necessary post-procedure care, recording vital signs and any concerning symptoms.
Understand and relate test findings to the patient’s condition, aiding in education and follow-up care plans.
SETTINGS CONNECTION: Medical Office
LPNs in medical offices often encounter diagnostic test results first. Recognizing severely abnormal values is vital to promptly inform healthcare providers to initiate early treatment.
PATIENT TEACHING CONNECTION
Preparing patients for tests can reduce anxiety, improve cooperation, and explain the procedure and its significance without using medical acronyms. Written materials can reinforce verbal instructions, ensuring comprehension. Consent must follow full teaching, ensuring patients are informed participants in their care.
CATEGORIES OF DIAGNOSTIC TESTS
Five categories include:
Laboratory tests: Involve biochemical analysis of blood and body fluids to assess various organ functions and disease markers.
Radiology and imaging tests: Visualize internal structures, allowing clinicians to diagnose injuries and conditions accurately.
Ultrasonography: Non-invasive imaging technique for assessing organ structure and function, particularly beneficial in obstetrics and urology.
Endoscopic examinations: Visual exploration of internal cavities, commonly utilized to examine the gastrointestinal and respiratory tracts.
Graphic recording tests: Measure electrical activities in organs like the heart and brain, aiding in the evaluation of functional conditions.
LABORATORY TESTS
Laboratory tests provide broad classifications examining various bodily fluids including blood, urine, and sputum. The normal production of blood cells is explained, highlighting their lifespan, functions, and the pathophysiology of their deterioration.
HEMATOLOGY
Complete Blood Count (CBC): Measures WBCs, RBCs, hemoglobin, and platelets; differentiates types of WBCs to provide a comprehensive view of hematological health.
Normal CBC Values
Component | Normal Range |
|---|---|
WBCs | 4,500–11,000 cells/mcL |
RBCs | 4.2–6.1 million cells/mcL (men) / 3.6–5.6 million cells/mcL (women) |
Hemoglobin | 14–18 g/dL (men) / 12–16 g/dL (women) |
Hematocrit | 40–52% (men) / 37–47% (women) |
Platelets | 150,000–450,000/mcL |
WHITE CELL COUNT AND DIFFERENTIAL
Leukocytosis (elevated WBC count) and Leukopenia (deceased WBC count) are explained. The roles of various WBC types are discussed in the context of immune response.
Key indicators include: Left shift (increase in immature neutrophils), suggesting acute infection, and Right shift (increase in mature lymphocytes), often indicated in chronic infections or viral conditions.
BLOOD CHEMISTRY TESTS
Blood chemistry tests analyze biological chemical reactions; common tests include:
Blood glucose: Measures sugar in the blood, critical for diabetes management.
Electrolyte levels: Assess sodium, potassium, chloride, and bicarbonate in maintaining fluid and acid-base balance.
Enzymes and isoenzymes: Evaluate liver and heart function through specific enzyme levels.
Blood urea nitrogen: Indicates kidney function and urinary health.
Serum creatinine: Primarily measures kidney excretion capability.
Total protein: Reflects nutritional status and potential liver disease.
Total bilirubin: A measure of liver function and hemolytic activity.
METABOLIC PANEL
A complete metabolic panel consists of 14 tests assessing liver, kidney, and pancreatic functions, as well as electrolyte balance.
OTHER BLOOD TESTS
Tests for B-type natriuretic peptide (BNP) that helps in diagnosing heart failure, as well as various cardiac enzymes (like troponins) that indicate myocardial infarction, lipase for diagnosing pancreatic diseases, and glycosylated hemoglobin (Hgb A1c) that reflects long-term glucose control.
URINE TESTS
Urinalysis evaluates physical appearance, chemical composition, and microscopic components, serving as a diagnostic tool for kidney function as well as systemic health assessment.
GLOMERULAR FILTRATION RATE
GFR measures kidney function. Anything below 60 mL/min indicates significant impairment and is critical for diagnosing chronic kidney disease.
RADIOLOGY AND IMAGING TESTS
X-rays, CT scans, and MRIs visualize internal structures, essential in diagnosing conditions such as fractures, tumors, and infections.
NURSING CARE FOR RADIOLOGICAL TESTS
Minimal nursing care is required for general imaging, but patient education about the procedures and comfort measures is essential for positive patient experiences.
MAGNETIC RESONANCE IMAGING
MRI utilizes magnetic fields for imaging; sedation may be required for claustrophobic patients. Comprehensive patient screenings for metal implants are crucial for safety.
COMPUTED TOMOGRAPHY
CT scans provide detailed cross-sectional images of internal organs; administration of contrast media requires prior evaluation of kidney function to prevent contrast-induced nephropathy.
ARTERIOGRAPHY AND VENOGRAPHY
Assess conditions related to blood flow and abnormalities; nursing care involves pre-test preparations, patient education about risks, and meticulous post-test monitoring for potential complications.
ULTRASONOGRAPHY
Non-invasive and painless imaging; it aids in assessing organ function, blood flow, and identifying abnormalities in a range of conditions.
ENDOSCOPIC EXAMINATIONS
Procedures like EGD and colonoscopy allow for direct visualization of the gastrointestinal tract; nursing care includes extensive patient preparation and monitoring for complications post-procedure.
GRAPHIC RECORDING TESTS
Electrocardiography (ECG) evaluates the electrical activity of the heart, while Electroencephalography (EEG) assesses brain activity, both requiring careful patient setup and data interpretation.
SKILL ASSESSMENT - ASPIRATION PROCEDURES
Outlined steps for assisting with lumbar puncture, paracentesis, and other aspiration procedures, focusing on assessment, planning, implementation, and evaluation according to best practices.
KEY POINTS
Nurses play a vital role in diagnostic testing preparation and care, ensuring safety, reliability, and patient understanding.
Understanding test types and corresponding nursing actions is essential for guaranteeing patient safety and fostering accurate diagnoses.
REVIEW QUESTIONS
Reportable urinalysis findings for common conditions such as urinary tract infections and renal disorders.
Preparatory steps for barium enema including dietary restrictions and patient education, and their significance in ensuring diagnostic accuracy.
Tests utilized for evaluating the large intestine, particularly focusing on indications and contraindications.
Implications and nursing considerations regarding a left shift in WBC counts, particularly in infection management.
Tests beneficial for kidney evaluation and their respective indicators for renal function.
Priority nursing actions for a patient post-femoral arteriogram, particularly monitoring for bleeding and assessing extremity perfusion.
Pre-paracentesis assessment of abdominal girth and its implications for fluid management.
Lead wire placement considerations during a 12-lead ECG to ensure the accuracy of cardiac monitoring data.
CRITICAL THINKING EXERCISES
Strategies to comfort a patient anxious about undergoing a colonoscopy or other invasive procedures.
Importance of thorough and patient-specific pre-test education in mitigating anxiety and enhancing cooperation during procedures.