LABORATORY AND DIAGNOSTIC TESTING

• Tests may be used for essential screening as part of a wellness check
• Frequently, tests help confirm a diagnosis, monitor an illness, and provide valuable information about the client's response to treatment
• Nurses require knowledge of the most common laboratory and diagnostic tests
• Nurses must also know the implications of the test results in order to provide the most appropriate nursing care for the client
• PRETEST


  • Major focus: client preparation
  • Thorough assessment and data collection to assist the nurse in determining communication and teaching strategies
  • Prior to radiologic studies it is important to ask female clients if pregnancy is possible
  • Nurse also needs to know what equipment and supplies are needed for the specific test
  • Laboratory at the facility can act as a resource for information
• Preparing for Diagnostic Testing


  1. Instruct the client and family about the procedure for the diagnostic test ordered

  2. Explain the purpose of the test

  3. Instruct the client and family about activity restrictions related to testing

  4. Instruct the client and family on the reaction the diagnostic test may produce

  5. Provide the client with detailed information about the diagnostic testing equipment

  6. Inform the client and family of the time frame for when the results will be available

  7. Instruct the client and family to ask any questions so that the health care provider can clarify information and any fears
• INTRATEST


  • Focuses on specimen collection and performing or assisting with certain diagnostic testing
  • Nurse uses standard precautions and sterile technique as appropriate
  • Nurse provides emotional and physical support while monitoring the client as needed
  • Nurse ensures correct labeling, storage, and transportation of the specimen to avoid invalid test results
• POST-TEST


  • Focus: nursing care of the client and follow-up activities and observations
  • Nurse compares the previous and current test results and modifies nursing interventions as needed
  • The nurse also reports the results to appropriate health team members
• Three components of specimen quality

  • Proper specimen selection (i.e., the correct type of specimen must be submitted)
  • Proper specimen collection
  • Proper transport of the specimen to the laboratory
• Complete Blood Count (CBC)


  • Specimens of venous blood are taken
  • It includes hemoglobin and hematocrit measurements, erythrocyte (red blood cells) count, red blood cell indices, leukocyte (white blood cell) count, a differential white cell count, and Platelets
  • Primary screening test and one of the most frequently ordered blood tests

  
• Bleeding Time


  • Measures the duration of bleeding after standardized skin incision
  • It depends on the elasticity of the blood vessel wall and the number and function of platelets
• Prothrombin time (PT)


  • Measures the time required for fibrin clot to form after addition of calcium ions and tissue thromboplastin
  • Test of choice for monitoring oral anticoagulant therapy
• Serum Electrolytes


  • Often routinely ordered for any client admitted to a hospital as a screening test for electrolyte and acid–base imbalances
  • Routinely assessed for clients at risks such as those being treated with a diuretic for hypertension or heart failure
• Normal electrolyte values for adults (venous blood)

  • Sodium: 135 - 145 mEq/L
  • Potassium: 3.5 - 5.0 mEq/L
  • Chloride: 95 - 105 mEq/L
  • Calcium (total) (ionized): 4.5 -5.5 mEq/L, or 8.5 - 10.5 mg/dL
  • Magnesium: 1.5-2.5 mEq/L or 1.6-2.5 mg/dL
  • Phosphate (phosphorous): 1.8-2.6 mEq/L
• Therapeutic Drug Monitoring


  • Often conducted when a client is taking a medication with a narrow therapeutic range (e.g., digoxin)
  • Blood samples for peak and trough levels to determine if the blood serum levels of a specific drug are at a therapeutic level and not a subtherapeutic or toxic level

  
• Arterial Blood Gases (ABG)


  • Measurement of arterial blood gases is an important diagnostic procedure
  • Important to prevent hemorrhaging by applying pressure to the puncture site for about 5 to 10 minutes after removing the needle
• Capillary Blood Glucose


  • Taken to measure the current blood glucose level when frequent tests are required or when a venipuncture cannot be performed
  • Technique is less painful than a venipuncture and easily performed
  • Clients can perform this technique on themselves
• CK (creatine kinase)


  • An enzyme found in the heart and skeletal muscles
  • Has three isoenzymes: MM or CK3, MB or CK2, and BB or CK1
• Troponin I/Troponin T


  • Cardiac troponin is highly concentrated in the heart muscle
  • This test is used in the early diagnosis of MI
• AMMONIA


  The test helps to monitor severe hepatic disease and the effectiveness of therapy
• BILIRUBIN


  • Evaluates liver function
  • The major product of hemoglobin catabolism
  • Significant in neonates because excessive unconjugated bilirubin can accumulate in the brain, causing irreversible damage
• Aspartate aminotransferase (AST)


  • Helps to diagnose acute hepatic disease and IM (Myocardial Infarction)
  • Monitor patients with cardiac and hepatic disease
• Alanine aminotransferase (ALT)


  • Helps to detect and evaluate the treatment of acute hepatic disease
  • Assesses the hepatotoxicity of some drugs
• AMYLASE


  • An enzyme that helps the body digest starch and glycogen in the mouth, stomach and intestine
  • Helps to evaluate possible pancreatic injury
• LIPASE


  • Converts triglycerides and other fats into fatty acids and glycerol
  • Diagnose acute pancreatitis
• URINALYSIS


  • Screens for renal or urinary tract disease and helps detect metabolic and systemic disease
  • Includes tests for specific gravity, pH, presence of abnormal constituents like glucose, ketones, protein, and occult blood
• Stool Specimen Collection


  1. Defecate in a clean bedpan or bedside commode

  2. Do not contaminate the specimen with urine or menstrual discharge

  3. Do not place toilet tissue in the bedpan after defecation

  4. Notify the nurse as soon as possible after defecation
• Sputum Specimen


  • Sputum is the mucous secretion from the lungs, bronchi, and trachea
  • It is essential to differentiate it from saliva, the clear liquid secreted by the salivary glands in the mouth, sometimes referred to as "spit"
• Reasons for collecting sputum specimens

  • For culture and sensitivity to identify a specific microorganism and its drug sensitivities
  • For acid-fast bacillus (AFB), which also requires serial collection, often for 3 consecutive days, to identify the presence of tuberculosis (TB)
  • To assess the effectiveness of therapy
• Anoscopy


  Viewing of the anal canal
• Proctoscopy


  Viewing of the rectum
• Proctosigmoidoscopy


  Viewing of the rectum and sigmoid colon
• Colonoscopy


  Viewing of the large intestine
• KUB


  1. ray of the kidneys/ureters/bladder to evaluate urinary tract structures
• Renal ultrasonography


  Noninvasive test that uses reflected sound waves to visualize the kidneys
• Cystoscopy


  Bladder, ureteral orifices, and urethra can be directly visualized using a cystoscope
• Electrocardiography (ECG)


  Provides a graphic recording of the heart's electrical activity
• Echocardiogram (2D echo)


  Noninvasive test that uses ultrasound to visualize structures of the heart and evaluate left ventricular function
• Aspiration


  Withdrawal of fluid that has abnormally collected or the obtaining of a specimen
• Biopsy


  Removal and examination of tissue, usually performed to determine a diagnosis or to detect malignancy