1. Unit 18 Laboratory Assistant Skills

2. Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED.2 18:1 Operating the Microscope  Many different models  Monocular microscopes – one eye piece  Binocular microscopes – two eye pieces  Quality varies  Calculation of magnification  Care and cleaning of microscope  Basic principles for operating a microscope

3. Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED.3 Types of Microscopes  Compound, bright-field  Epiflourescence  Electron  Purpose: magnify or enlarge objects so they become more visible

4. Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED.4 Parts of a Microscope  Base  Arm  Eyepieces or ocular viewpieces  Objectives  Revolving nosepiece  Stage

5. Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED.5 Parts of a Microscope (continued)  Coarse adjustment  Fine adjustment  Iris diaphragm  Illuminating light

6. Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED.6 18:2 Obtaining and Handling Cultures  Obtained when doctor wants to identify the causative agent of a disease  Sample specimen is either examined at that time or grown and then examined  Use sterile applicator swab to collect specimen  Keep specimen moist and free from contact with anything else

7. Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED.7 Obtaining and Handling Cultures (continued)  Direct smear or bacteriological smear  Agar plate, culture plate, petri dish, culture media tube  Culture and sensitivity  Resistant organisms  Sensitive organisms

8. Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED.8 Obtaining and Handling Cultures (continued)  Fixing a slide  Gram’s stain  Standard precautions  Basic principles for obtaining a culture specimen  Basic principles for preparing a direct smear

9. Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED.9 Obtaining and Handling Cultures (continued)  Basic principles for streaking an agar plate  Basic principles for transferring culture from agar plate to slide  Basic principles for staining with Gram’s stain

10. Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED.10 18:3 Puncturing the Skin to Obtain Capillary Blood  Often used to assist physician in making a diagnosis  Responsibility for obtaining blood for various blood test varies –Check your state regulations –Always know what you are permitted to do

11. Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED.11 Methods of Obtaining Blood  Skin puncture  Venipuncture  Arterial blood

12. Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED.12 Skin Puncture  Aseptic technique  Common puncture sites  Points to check prior to skin puncture  Proper type of puncture  Always remove first drop of blood  After puncture specimen obtained  Always use standard precautions

13. Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED.13 18:4 Performing a Microhematocrit  Also called HCT or “crit”  Measures volume of packed red blood cells (RBCs) or erythrocytes in the blood  Often described as percentage of RBCs per volume of blood  Different methods  Microhematocrit centrifuge

14. Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED.14 Performing a Microhematocrit (continued)  Capillary tubes  Normal values  Abnormal readings  Accuracy is essential  Careful recording of tests  Physician’s responsibility to report test results to patient

15. Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED.15 18:5 Measuring Hemoglobin  Used to determine oxygen-carrying capacity of the blood  Hemolysis  Hemoglobinometer  Automated photometer  Normal values

16. Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED.16 Measuring Hemoglobin (continued)  Abnormal values  Accuracy is essential  Basic principles of using a hemoglobinometer  Basic principles of using a photometer

17. Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED.17 18:6 Counting Blood Cells  Erythrocyte and leukocyte counts are done to determine the number of blood cells in the blood  Methods used  Hemacytometer counting chamber  Must dilute blood first

18. Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED.18 Counting Blood Cells (continued)  Microscopic powers used  Normal values  Accuracy is essential  Basic principles for counting blood cells

19. Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED.19 18:7 Preparing and Staining a Blood Film or Smear  Preparation of blood film or smear  Uses of blood film or smear  Equipment must be extremely clean  Wright’s stain  Quick stain (three-step method)

20. Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED.20 Preparing and Staining a Blood Film or Smear (continued)  Basic principles for preparing  Basic principles for staining with Wright’s stain  Basic principles for staining with a quick stain kit

21. Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED.21 18:8 Testing for Blood Types  Blood types inherited from parents  Type of blood determined by presence of certain factors called antigens on red blood cells  Antigen  ABO blood type system  Rh type system

22. Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED.22 Testing for Blood Types (continued)  Antigen-antibody reaction  Typing and crossmatch  Hemolytic disease of the newborn (HDN)  Using anti-serums for blood typing  Basic principles for testing for blood types with anti-serum

23. Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED.23 18:9 Performing an Erythrocyte Sedimentation Rate (ESR)  Measures the distance that red blood cells have fallen or settled to the bottom of a glass test tube in a specific period of time  Also called sedimentation rate or sed rate  Basic procedure for test

24. Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED.24 Performing an ESR (continued)  Special rack used for ESR  Measurements usually taken at specific time periods  Normal values can vary slightly  Abnormal readings  Basic principles for performing erythrocyte sedimentation rate

25. Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED.25 18:10 Measuring Blood-Sugar (Glucose) Level  Glucose metabolism  Diabetes mellitus  Control of diabetes mellitus  Fasting blood sugar (FBS)  Glucose tolerance test (GTT)  Glycohemoglobin test (HbA1C or HbA1)

26. Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED.26 Urine Tests  Previously, diabetics used urine tests to check level of glucose  High glucose in urine would indicate high glucose in blood  Urine tests are not as accurate because kidney function varies between individuals  Most diabetics use blood testing now

27. Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED.27 Blood Glucose  Advantages of checking blood glucose versus urine glucose  Testing blood with reagent strips  Proper care of reagent strips  Proper use and care of glucose meter  Instructions to patients  Basic principles for measuring blood- sugar/glucose level

28. Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED.28 Summary  Different blood tests are used to diagnose disease  Accuracy is essential with any test  Standard precautions must be observed at all times

29. Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED.29 18:11 Testing Urine  Often done to determine physical condition of patient  Abnormal urine tests are often the first indication of disease  Important to know normal and abnormal characteristics of urine

30. Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED.30 Testing Urine (continued)  Volume  Color  Transparency  Odor  pH reaction  Specific gravity

31. Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED.31 Testing Urine (continued)  Glucose  Albumin or protein  Acetones or ketones  Blood  Pus  Bacteria

32. Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED.32 Testing Urine (continued)  Red blood cells (erythrocytes)  White blood cells (leukocytes)  Bilirubin  Urobilinogen

33. Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED.33 Urinalysis  Examination of the urine  Includes physical, chemical, and microscopic testing  Physical examination usually done first  Chemical testing  Microscopic examination  Urine should be fresh – more accurate  Standard precautions

34. Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED.34 18:12 Using Reagent Strips to Test Urine  Commonly used for chemical testing of urine  Reagent strips  Storage of strips  Chemical reactants – note expiration

35. Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED.35 Using Reagent Strips to Test Urine (continued)  pH  Protein  Glucose  Ketone or acetone  Blood  Bilirubin  Urobilinogen

36. Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED.36 Using Reagent Strips to Test Urine (continued)  Types of reagent strips  Automated strip readers or analyzers  Read instructions carefully  Fresh urine specimen should be used  Record results of test correctly  Basic principles of testing urine with reagent strips

37. Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED.37 18:13 Measuring Specific Gravity  Specific gravity defined  Low specific gravity of urine  High specific gravity of urine  Urinometer  Refractometer  Basic principles for measuring specific gravity

38. Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED.38 18:14 Preparing Urine for Microscopic Examination  Purpose  Fresh, first-voided morning specimen preferred  Only portion examined  Size of drop of concentrated urine examined is important

39. Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED.39 Preparing Urine for Microscopic Examination (continued)  Urinary sediment should be examined immediately  Identification of substances present  Basic principles for preparing urine

40. Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED.40 Summary  Substances present in urine are often first indication of disease  Variety of urine tests performed to check for these substances  Observe standard precautions while performing any urine tests