Diagnostic Testing: Blood Tests, Urine and Stool Analysis - PDF

Diagnostic Testing: Part I  Learning Objectives Recall the types of cells found in blood and their functions. Identify common blood tests, their purposes, and their normal values. Discuss other laboratory tests, such as urine and stool studies, and their purposes and no...

Diagnostic Testing: Part I  Learning Objectives Recall the types of cells found in blood and their functions. Identify common blood tests, their purposes, and their normal values. Discuss other laboratory tests, such as urine and stool studies, and their purposes and normal values. Explain the purpose of common diagnostic tests. Describe assessment procedures for patients undergoing diagnostic tests. Develop appropriate nursing diagnoses associated with diagnostic testing. Generate goals to meet individual patient problems. Describe the nurse’s role in implementation and evaluation of the plan of care before, during, and after diagnostic tests and procedures. Normal Structure and Function Of Blood Cells Erythrocytes (RBCs): O2 and CO2 transport Thrombocytes (platelets): trigger clotting factors Leukocytes (WBCs): inflammatory and immune response; found primarily in bone marrow except for T lymphocytes (produced in thymus) Lymphocytes (T and B) Monocytes​ Eosinophils​ Neutrophils​ Basophils​ Normal Structure and Function Of Blood Cells Plasma ​ Fluid portion of blood​ Transports electrolytes to and from cells​ Contains nutrients and proteins​ Transports hormones throughout the body​ Transports waste products​ Normal Structure and Function Of Blood Cells Plasma proteins​ Albumin: responsible for maintaining fluid balance by providing colloidal osmotic pressure; can enhance bioavailability of drugs Fibrinogen: important for blood coagulation – converts into fibrin threads with ionized calcium Globulins (alpha, beta, gamma): some function as antibodies; others responsible for enzymatic functions; responsible for transport of lipids, iron, and copper ​ Normal Structure and Function Of Blood Cells Plasma Contains glucose, amino acids, fatty acids and vitamins Transports hormones throughout the body Blood also transports waste products urea and creatinine for renal excretion  Laboratory Tests: Blood ​ Blood samples​ Complete blood count (CBC)​ Venous: primary source of Information on oxygen and sampling​ carbon dioxide transport​ Arterial: determination of Information on immune/ arterial blood gases (ABGs)​ inflammatory response​ Capillary: glucose, cholesterol levels, clotting times, Know the normal ranges for CBC and what values mean hemoglobin, and hematocrit​ (see Chapter 34, Fundamentals of Nursing)  Laboratory Tests: Blood ​ CBC components​ Coagulation studies​ Red blood cell (RBC) count​ Blood vessel injury​ Hemoglobin level​ Vascular spasm​ Hematocrit​ Plug formation​ RBC indices​ Blood clotting​ White blood cell (WBC) count​ Differential WBC count​ Laboratory Tests: Blood ​ Diagnostic tests measure:​ Platelets: number, size, and shape of cells Prothrombin time (PT): Can detect bleeding disorders caused by abnormalities of the extrinsic clotting system; used to monitor effectiveness of warfarin therapy International normalized ratio (INR): used to monitor effect of anticoagulant therapy Activated partial thromboplastin time (APTT): Can detect bleeding disorders caused by abnormalities of the intrinsic clotting system; used to monitor effectiveness of heparin therapy Fibrinogen: used to identify suspected bleeding disorders and to monitor progressive liver disease Know the normal ranges for coagulation studies and what values mean (see Chapter 34, Fundamentals of Nursing)  Know the normal ranges for electrolytes, BMP, glucose and Laboratory Tests: Blood ​ HgbA1c and what values mean (see Chapter 34, Fundamentals Blood chemistry​ of Nursing) Electrolytes ​ ▪ Cations: positively charged​ ▪ Anions: negatively charged ​ Basic metabolic panel (BMP): sodium, potassium, chloride, CO2, BUN, serum creatinine Glucose​ ▪ Controlled by two hormones: glucagon and insulin​ ▪ Monitoring serum levels of glucose is useful in detecting abnormal glucose metabolism​ Hemoglobin A1c (Hgb A1c)​ ▪ Evaluates blood glucose levels over a period of 2 to 3 months ​ Laboratory Tests: Blood ​ Kidney function tests​ Blood urea nitrogen (BUN): urea is a by-product of protein metabolism Serum creatinine: waste product of skeletal muscle metabolism Glomerular filtration rate (GFR): mLs filtered by the kidneys per minute Lipid profile​ Total cholesterol Low-density lipoprotein (LDL) cholesterol: transport lipids from liver to body High-density lipoprotein (HDL) cholesterol: transport excess cholesterol back to liver Triglycerides​: fatty acids, protein and glucose; stored in adipose tissue and muscle Laboratory Tests: Blood ​ Liver function tests​ (liver profile​) Albumin: plasma protein synthesized by liver; responsible for maintaining colloidal oncotic pressure in the vascular and extravascular spaces; indicates nutritional status Prealbumin: plasma protein synthesized by liver; much shorter half-life than albumin Bilirubin: one of the components of bile, is synthesized in the liver, spleen, and bone marrow; by-product of hemolysis Laboratory Tests: Blood ​ Liver function tests​ (liver profile​) Alanine aminotransferase (ALT): enzyme found primarily in the liver; also is found in the kidneys, heart, and skeletal muscle; catalyst for amino acid production; used to monitor liver disease progression and the effect of hepatotoxic drugs Alkaline phosphatase (ALP): enzyme found primarily in the liver; also is found in the bone, placenta, intestine, and kidneys; useful indicator of liver and bone disease Aspartate aminotransferase (AST): enzyme found primarily in the heart, liver, and muscle; released after cell death or injury; used to assess the severity of liver damage and disease Gamma-glutamyl transpeptidase (GGTP): found primarily in the liver and biliary tract; assists the transportation of amino acids across cell membranes; may indicate liver disease Laboratory Tests: Blood ​ Cardiac markers​: proteins that leak out of injured heart muscle cells into the bloodstream Creatine kinase: ​enzyme found primarily in skeletal muscle, cardiac muscle, and brain tissue; elevated levels usually indicate damage CK-BB (brain), CK-MB (heart), CK-MM (skeletal muscle) Myoglobin​: oxygen-transporting and storage protein found in cardiac and skeletal muscle; when damage to muscle occurs, myoglobin is released and blood levels of the protein rise Troponin: complex of three proteins found in cardiac and skeletal muscle; released during myocardial damage and can be detected as early as 4 hours after an MI Used much more frequently in the clinical setting to detect an MI than CK-MB or myoglobin Laboratory Tests: Blood ​ Cardiac markers: proteins that leak out of injured heart muscle cells into the bloodstream Homocysteine​: amino acid formed in the conversion of methionine to cysteine; folate and vitamins B6, B12 necessary for the body to metabolize homocysteine; associated with an increased risk of cardiovascular disease Brain natriuretic peptide (BNP): hormone produced by myocardial cells; released from the ventricle during times of increased pressure or overload; elevated levels are often found in patients with heart failure, and plasma concentrations reflect the severity of cardiac failure C-reactive protein (CRP): produced by the liver in response to inflammation, tissue damage, and infection. Blood levels of CRP have been used as a marker for inflammatory and autoimmune disorders Arterial blood gas (ABG): used to examine arterial blood and assess a patient’s oxygenation status and acid–base balance Laboratory Tests: Urine and Stool Urinalysis​ Used to diagnose urinary tract infections ​ Helpful in detecting diseases and disorders unrelated to the renal system​ Laboratory Tests: Urine and Stool Stool​ Culture and sensitivity​ Used to identify disorders of the Common sources for culture specimens: gastrointestinal (GI) tract, liver, and blood, throat, sputum, stool, urine, and pancreas​ wounds Tests: occult blood, fecal fat (steatorrhea), Culture is considered positive when urobilinogen (biliary obstruction or liver sufficient bacteria are found growing on the disease), and ova and parasites medium Black, tarry stools = upper GI; bright red After the pathogen has been identified, it is blood=lower GI exposed to various antibiotics, and the bacterial growth is monitored to determine sensitivity (which antibiotic therapy would be most effective in treating the infection) Diagnostic Examinations Radiography ​ Noncontrast studies ▪ X-rays: chest, bones, and abdomen ▪ Mammograms ​ Contrast studies: potential for causing allergic reactions ▪ Intravenous pyelogram: GU, GI = KUB (kidneys, ureters, bladder) ▪ Upper GI (barium swallow): esophagus, stomach, duodenum, and upper portion of the jejunum ▪ Lower GI (barium enema): ascending, transverse, and descending colons, as well as the sigmoid colon and rectum Diagnostic Examinations Radiography ​ Computed tomography ▪ Special scanner allows cross-sectional images of an organ to be visualized ▪ Can be done with or without the use of a contrast medium ▪ Abdomen, brain, chest, kidneys, ureters Diagnostic Examinations Magnetic resonance imaging (MRI) Most common diagnostic examination for brain pathology and joint visualization; produces a cross-sectional image of the body but without radiation exposure Disadvantages: cost, contraindications Positron emission tomography (PET) Nuclear study performed after IV injection of radioactive chemicals; color-coded images that can be analyzed Brain, heart; oncology Electrocardiogram​ (ECG, EKG): waveform changes can indicate cardiac injury, disorders of the electrical conduction system, or cardiac enlargement Diagnostic Examinations Endoscopy Examination of the interior of an organ or cavity by means of a fiberoptic video endoscope Separate ports allow instillation of drugs, suction, and insertion of instruments for tissue or foreign object removal Ultrasound​ Provides visualization of soft-tissue organs by recording and measuring the reflection of ultrasonic waves Needle aspirations and biopsies Paracentesis: removes ascites fluid from the peritoneal cavity Thoracentesis: removes fluid from the pleural space Biopsy: can be completed surgically through an incision, through laparoscopic and endoscopic methods, by scraping or using a punch or needle, or excising with a scalpel Diagnostic Testing: Part II Specimen Collection: Principles for Practice Correctly collect specimens Monitor patient outcomes Ensure laboratory tests are performed Share results with the interdisciplinary team Use proficiency and judgment in obtaining specimens to minimize patient discomfort, promote patient safety, and ensure accuracy and quality of diagnostic procedures Everyone who handles body fluids is at risk for exposure. Use hand hygiene, clean gloves or personal protective equipment. Properly label containers Test values may vary by agency; value ranges are for normal, high, and low results, plus critical value ranges. When questions arise, consult the health care agency procedure manual, or call the laboratory Urine Specimen Collection Urinalysis: provides information about kidney or metabolic function, nutrition, and systemic diseases Types of urine tests and specimens Random urine specimen for routine urinalysis Culture and sensitivity (C&S) of urine Timed urine specimen for quantitative analysis Chemical properties of urine Urine Specimen Collection Delegation The skill of collecting urine specimens can be delegated to assistive personnel (AP). The nurse instructs the AP to: Obtain the specimens at a specified time as ordered or per protocol Position patient as necessary when mobility restrictions are present Report to the nurse if the urine is not clear Report to the nurse when a patient is unable to initiate a stream or has pain or burning on urination Urine Specimen Collection Unexpected outcomes and related interventions Urine specimen is contaminated with stool/toilet paper Repeat patient instruction and specimen collection. If unable to obtain specimen through clean voiding, patient may need catheterization Urine culture reveals bacterial growth Report findings to health care provider Administer medications as ordered Monitor patient for fever and dysuria Urine Specimen Collection Unexpected outcomes and related interventions Lumen leading to balloon that holds catheter in place is punctured Notify health care provider Prepare for removal of existing catheter and insertion of new catheter Collecting a Timed Urine Specimen Some renal function and urine composition tests require urine collected over 2 to 72 hours 24-hour timed collection Most common Measures elements such as amino acids, creatinine, hormones, glucose, and adrenocorticosteroids Requires teamwork Collecting a Timed Urine Specimen Delegation The skill of collecting a timed urine specimen can be delegated to AP. The nurse informs the AP about: When timed collection begins, proper method to store the collected urine, where to place signs that a timed urine collection is in progress, and saving all urine Measuring Occult Blood in Stool Hemoccult testing: used to screen for occult (not visible) blood in stool DNA stool sample test: identifies nonbleeding polyps with abnormal DNA Delegation The skill of testing stool for occult blood can be delegated to AP. The nurse informs the AP to: Report immediately if any blood is detected, and not discard stool from a positive test so the nurse may repeat the testing Measuring Occult Blood in Stool Unexpected outcomes and related interventions Test for occult blood is positive Continue to monitor patient. Notify health care provider. Collecting Nose and Throat Specimens for Culture Nose or throat culture Simple diagnostic tool to identify the presence and type of microorganisms Obtain culture specimens before antibiotic therapy is initiated Delegation The skill of obtaining specimens from the nose and throat cannot be delegated to assistive personnel (AP). Collecting Nose and Throat Specimens for Culture Unexpected outcomes and related interventions Nose and throat cultures reveal bacterial growth Notify health care provider of findings. Administer medications as ordered Patient experiences minor nasal bleeding Apply mild pressure and ice pack over bridge of nose Notify health care provider of patient’s condition Specimen is contaminated Repeat specimen collection Blood Glucose Monitoring Blood glucose monitoring (BMG) is an essential component of any diabetes self-management program Blood glucose reflectance meters Continuous glucose monitoring system with implantable glucose sensor Blood Glucose Monitoring Delegation Assessment of a patient’s condition cannot be delegated to AP. When the patient’s condition is stable, the skill of obtaining and testing a sample of blood for blood glucose level can be delegated to AP. The nurse informs the AP by: Explaining appropriate sites to use for puncture and when to obtain glucose levels Reviewing expected blood glucose levels and when to report unexpected glucose levels to the nurse, so the nurse can retake blood glucose level as per agency policy Blood Glucose Monitoring Unexpected outcomes and related interventions Puncture site is bruised or continues to bleed Apply pressure Notify health care provider if bleeding continues Blood glucose level is above or below target range Continue to monitor patient Check if there are medication orders for deviations in glucose level Notify health care provider Administer insulin or carbohydrate source as ordered, depending on glucose level Glucose meter malfunctions Review instructions for troubleshooting glucose meter Repeat test  Diagnostic Procedures: Safety Guidelines Diagnostic procedures are performed at patients’ bedsides or in specially equipped rooms within a health care agency or outpatient care setting Nurse is responsible for Assessing a patient’s knowledge of a procedure Preparing the patient Providing a safe environment and emotional support Providing pre-procedure and post-procedure assessment, care, and documentation Providing discharge teaching  Diagnostic Procedures: Safety Guidelines Ensure patients understand their testing and post-procedural care requirements. Some tests require intravenous (IV) sedation along with the diagnostic procedure such as a gastrointestinal (GI) endoscopy; others require contrast media or aspirations Diagnostic procedures pose some risk for the patient. It is important to understand the procedure, risks, and appropriate post-procedural nursing care IV sedation is used for diagnostic or surgical procedures that do not require complete or general anesthesia. Sedation classifications include “minimal,” “moderate,” or “deep” sedation/analgesia  Diagnostic Procedures: Safety Guidelines Before a procedure Ensure patient undergoes correct procedure Assess for completion of relevant documentation Identify any medications for which uninterrupted dosing is required Verify that informed consent was obtained before sedatives are administered Ensure interpreter is used and documented in the consent form, if needed Ensure emergency equipment is available and functioning Confirm presence and date of expiration for sedation reversal agents  Diagnostic Procedures: Safety Guidelines During a procedure When a procedure involves the use of radiation: ▪ Minimize the amount of radiation exposure ▪ Monitor staff radiation exposure with the use of a dosimeter if necessary ▪ Remain positioned as far away from the radiographic equipment as possible while performing required patient care Monitor physiological parameters as indicated Position patients carefully to avoid injury Label specimens properly  Diagnostic Procedures: Safety Guidelines After the procedure Assess for possible procedural complications and conduct appropriate assessments for early detection Monitor oxygen saturation and vital signs to detect sedation failure and adverse effects Know the use, side effects, and complications of the sedative and reversal agents to be administered Be able to recognize cardiac dysrhythmias Institute fall precautions Timely and complete neurovascular checks