Copyright © 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Chapter 20 Laboratory Assistant Skills

Copyright © 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20:1 Operating the Microscope Instrument used to magnify and visualize objects too small for human eye Monocular microscope: one eyepiece Binocular microscope: two eyepieces Quality varies Refer to Procedure 20:1 in Text

Copyright © 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20:1 Operating the Microscope Compound, bright-field microscope is commonly used Epifluorescence microscope – Used with fluorescent dye stain Electron microscope – Used to view extremely small objects

Copyright © 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20:1 Operating the Microscope Microscope parts (refer to Figure 20-2 in Text) – Base – Arm – Eyepiece(s) – Objectives – Revolving nosepiece – Stage

Copyright © 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20:1 Operating the Microscope Microscope parts – Coarse adjustment – Fine adjustment – Condenser and iris diaphragm – Illuminating light – Body tube

Copyright © 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20:2 Obtaining and Handling Cultures Culture specimen is obtained when physician wants to identify causative agent of a disease Sample specimen is examined right away or grown and then examined Sterile collection container and swab to collect culture Container with proper medium for culture

Copyright © 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20:2 Obtaining and Handling Cultures Direct smear or bacteriological smear Agar plate (culture plate, petri dish) or culture media tube Culture and sensitivity (C&S) study – Resistant organisms – Sensitive organisms

Copyright © 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20:2 Obtaining and Handling Cultures Fixing a slide Gram’s stain technique – Gram positive, gram negative Rapid identification tests for common bacteria Use standard precautions Refer to Procedures 20:2A–20:2E in Text

Copyright © 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20:3 Puncturing the Skin to Obtain Capillary Blood Blood tests used to assist physicians in making diagnoses Responsibility for obtaining blood for blood tests varies – Check your state regulations – Always know what you are permitted to do

Copyright © 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20:3 Puncturing the Skin to Obtain Capillary Blood Types of blood draw – Skin puncture – Venipuncture – Arterial blood Follow careful aseptic technique Refer to Procedure 20:3 in Text

Copyright © 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20:3 Puncturing the Skin to Obtain Capillary Blood Know common puncture sites (refer to Figure in Text) Placement of skin puncture Always remove first drop of blood Procedure after puncture specimen obtained Always use standard precautions

Copyright © 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20:4 Performing a Microhematocrit Also called HCT or “crit” Measures volume of packed red blood cells (RBCs), or erythrocytes, in blood – Erythrocytes carry oxygen from lungs to body and carbon dioxide from body cells to lungs Described as percentage of RBCs per volume of blood

Copyright © 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20:4 Performing a Microhematocrit Different methods Microhematocrit requires less blood and takes less time than other methods Centrifuge separates blood into RBCs, buffy coat, and plasma Leukocytes (white blood cells) fight infection

Copyright © 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20:4 Performing a Microhematocrit Anticoagulants and special capillary tubes Normal values vary slightly – Low hematocrit: anemia – High hematocrit: polycythemia Physician must interpret test results for patient Refer to Procedure 20:4 in Text

Copyright © 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20:5 Measuring Hemoglobin Hemoglobin (Hgb) determines oxygen- carrying capacity of the blood Hemolysis – Destruction of RBCs, release of hemoglobin Hemoglobinometer – Measures hemoglobin concentration in blood

Copyright © 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20:5 Measuring Hemoglobin Disposable cuvette, test slide, or test strip with hemolyzing solution used to obtain blood sample Normal values vary by test type Double-check readings for accuracy Physician must interpret test results Refer to Procedure 20:5 in Text

Copyright © 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20:6 Preparing and Staining a Blood Film or Smear Prepared by placing small drop of blood on a slide, then spreading blood in thin layer using another slide, coverslip, or spreader Uses of blood film or smear – Differential count of WBCs – Examine erythrocytes

Copyright © 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20:6 Preparing and Staining a Blood Film or Smear Equipment must be extremely clean Cells must be stained for microscope viewing – Wright ’ s stain – Quick stain (three-step method) Follow manufacturer’s instructions Refer to Procedures 20:6A–20:6B in Text

Copyright © 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20:7 Testing for Blood Types Blood types inherited from parents Type of blood determined by presence of antigens on red blood cells Antigen causes production of antibody – ABO blood type system – Rh system

Copyright © 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20:7 Testing for Blood Types Blood types – Type A contains antigen A on RBCs – Type B contains antigen B on RBCs – Type AB contains antigens A and B of RBCs – Type O contains neither antigen on RBCs Rh type and antigen-antibody reaction

Copyright © 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20:7 Testing for Blood Types Blood typing and crossmatch Blood banks also do antibody screen Hemolytic disease of the newborn (HDN) Blood typing with anti-serums (refer to Figure and Procedure 20:7 in Text)

Copyright © 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20:8 Performing an Erythrocyte Sedimentation Rate Erythrocyte sedimentation rate (ESR) – Measures distance red blood cells fall and settle in a special glass test tube in a specific period of time – Also called sedimentation rate or sed rate Must be performed at room temperature Special rack used for ESR

Copyright © 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20:8 Performing an ESR Measurements taken at specific time periods Wintrobe or Westergren methods Normal values can vary slightly Abnormal rates may indicate inflammation, polycythemia, and other diseases Refer to Procedure 20:8 in Text

Copyright © 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20:9 Measuring Blood Sugar (Glucose) Level Glucose Form of sugar found in bloodstream Insulin allows metabolism of glucose Insufficient insulin: diabetes mellitus – Hyperglycemia, glycosuria – Treated with diet, insulin injections

Copyright © 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20:9 Measuring Blood Sugar (Glucose) Level Tests for glucose level – Fasting blood sugar (FBS) – Glucose tolerance test (GTT) – Glycohemoglobin test (HbA1C or HbA1)

Copyright © 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20:9 Measuring Blood Sugar (Glucose) Level Diabetics used urine tests to check level of glucose – Urine tests are not as accurate because kidney function varies between individuals Most diabetics use blood testing now – Reagent strips for rapid blood testing

Copyright © 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20:9 Measuring Blood Sugar (Glucose) Level Proper storage of reagent strips Proper use and care of glucose meter Most diabetic patients—even children— monitor their own blood sugar levels Refer to Procedure 20:9 in Text

Copyright © 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20:10 Testing Urine Often done to determine physical condition of patient Abnormal urine tests are often the first indication of a disease process Know normal and abnormal characteristics of urine (refer to Table 20-1 in Text)

Copyright © 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20:10 Testing Urine Urinalysis: physical, chemical, and microscopic texting of urine Physical testing of urine includes – Color—Odor – Transparency—Specific gravity

Copyright © 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20:10 Testing Urine Chemical testing of urine includes – Ph – Protein – Glucose – Ketone – Bilirubin – Urobilinogen – Blood

Copyright © 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20:10 Testing Urine Microscopic testing of urine includes – Cells – Casts – Crystals – Amorphous deposits

Copyright © 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20:10 Testing Urine Collection of urine in specimen containers Urine should be fresh and warm for more accurate results – Examined within 1 hour or refrigerated Follow standard precautions

Copyright © 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20:11 Using Reagent Strips to Test Urine Read and follow manufacturer’s directions Reagent strips contain chemical reactants that react to a specific substance – If the substance is present, the reagent strip changes color Store reagent strips properly

Copyright © 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20:11 Using Reagent Strips to Test Urine Reagent strips test for – Ph—Blood – Protein—Bilirubin – Glucose—Urobilinogen – Ketones/acetones—Phenylalanine Many different reagents strips are available

Copyright © 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20:11 Using Reagent Strips to Test Urine Color comparison chart on or with bottle Daily quality-control checks Automated strip readers – More accurate but expensive Record results of test properly Refer to Procedure 20:11 in Text

Copyright © 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20:12 Measuring Specific Gravity Specific gravity – Measurement of concentration of urine Low specific gravity of urine – Below 1.005; diluted urine High specific gravity of urine – Above 1.030; concentrated urine

Copyright © 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20:12 Measuring Specific Gravity Measurement with a urinometer Measurement with a refractometer or digital refractometer – Test for accuracy before use Refer to Procedure 20:12 in Text

Copyright © 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20:13 Preparing Urine for Microscopic Examination To examine urinary sediment – Certain substances indicate disease conditions Fresh, first-voided, early morning specimen preferred – Most concentrated specimen

Copyright © 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20:13 Preparing Urine for Microscopic Examination Only a portion of urine specimen is examined Size of drop of concentrated urine examined is important Urinary sediment should be examined immediately after placement on a slide

Copyright © 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20:13 Preparing Urine for Microscopic Examination Identification of substances present – Refer to Figure in Text – Requires training and experience Must be legally qualified to examine sediment Refer to Procedure 20:13 in Text