Pathology & Forensic Science

Pathology & Forensic Science Curriculum Supplement Published July 2013 Developed By Public Schools of North Carolina State Board of Education ncabr.org Department of Public Instruction Section 1: Diagnostic Services in Health Care Reference Article: What’s Wrong With Me?: The Role of Diagnostic Services in Health Care 4 Teacher Activity Overview: What Are My Test Results? 14 Student Worksheet: What Are My Test Results? 18 Section 2: Autopsy Reference Article: Autopsy 24 Teacher Activity Overview: What Happens to the Body? 31 Student Worksheet: What Happens to the Body? 35 Section 3: DNA Analysis Reference Article: DNA Analysis in Medicine and Forensics 42 Teacher Activity Overview: Why Bank My DNA? 50 Student Worksheet: Why Bank My DNA? 55 Section 4: Applications of Forensic Science Reference Article: Applications of Forensic Science 58 Teacher Activity Overview: What Did the Test Find? 65 Student Worksheet: What Did the Test Find? 74 Section 5: Uncertainty in Medical Testing Reference Article: Uncertainty in Medical Testing 80 Teacher Activity Overview: What is a False Positive? 86 Student Worksheet: What is a False Positive? 92 Pathology & Forensic Science: Table of Contents 2 Section 1 Diagnostic Services in Health Care What’s Wrong With Me? The Role of Diagnostic Services in Health Care Reference Article Imagine you have been feeling fatigued progression of diseases and determine the for several weeks and you visit a doctor to effectiveness of treatment. Many of these find out what’s wrong. Because fatigue is tests also are used in forensic medicine a sign of many diseases, the doctor must (applying medical knowledge to legal is- figure out its cause in order to treat you sues). In order for a diagnostic test to be properly. The cause might be anemia. It accurate, correct procedures must be fol- might be a low-grade infection. Maybe lowed. It also is important to understand it’s allergies or diabetes. The doctor will the possibility of both false negative and ask you some questions and do a physical false positive tests. New technologies are examination to narrow the possibilities. helping clinicians diagnose conditions He or she might also order laboratory tests, more quickly and helping researchers such as a blood test or urinalysis. better understand the origins of disease conditions. A wide range of diagnostic services are available to help medical professionals Quality Procedures diagnose the cause of various symptoms, Diagnostic tests may be done in a doctor’s choose a treatment plan, monitor the office, hospital or clinic laboratory. Some Pathology & Forensic Science: Diagnostic Services in Health Care 4 tests require a patient specimen (sample) samples must be packaged carefully and of blood, urine or other body tissue, while treated as biological hazards for transport. other tests involve imaging technology. After testing is complete, the specimens Patient specimens may be sent to a pri- usually must be kept for a period specified vate, commercial facility, often called a by regulations and then disposed in accor- reference laboratory. Careful adherence to dance with federal and state regulations. standard laboratory procedures for either In addition to the biohazards presented by type of test — from collecting the patient patient tissue, potential hazards are posed specimen or image to testing and report- by the chemical reagents used in the tests. ing results — is essential to patient safety. Diagnostic machines also must be well Hospitals and large clinics often use maintained and calibrated correctly. Con- barcode labels to automate recordkeeping. gress passed the Clinical Laboratory Im- Each specimen or image also is labeled provement Amendments in 1988 to ensure with at least two patient identifiers, such the accuracy of diagnostic testing. Under as name and date of birth. Identifiers that this law, the federal government regulates aren’t necessarily specific to each patient, many aspects of laboratory operation, such as hospital room number, no longer including the training of employees and are used. Labeling should be done in the the types and quality of instruments used presence of the patient to prevent mis- to analyze samples. Laboratory person- identification of records. If you give blood nel follow specific protocols for each test. or have a lab test done, you should make These are known as standard operating sure the person performing the test checks procedures, or SOPs. An SOP ensures a test and rechecks your identifying information. is done the same way each time, which This is part of a national effort to improve helps ensure the accuracy of the results. patient safety by accurately identifying Laboratory procedures are documented ex- patient specimens and images. tensively in diagnostic testing, just as they are during the manufacture of vaccines, Lab tests are becoming more and more therapeutic drugs and medical devices. automated, and the diagnostic machines Records must be kept of the calibration and used for these tests only produce accurate maintenance of instrumentation, the re- results when the patient specimens are agents used and any problems that occur. collected and packaged correctly, are stored To check if the tests are accurate, labora- in conditions that avoid sunlight and ex- tories regularly test known samples. They treme temperatures, and are transported also are required to participate in profi- quickly. To protect workers and the pub- ciency testing, in which an outside agency lic from possibly infectious samples, the sends unannounced samples to be tested. Pathology & Forensic Science: Diagnostic Services in Health Care 5 In this case, the outside agency knows the Blood correct results, while the laboratory does Blood has many useful components for not. Laboratories are inspected regularly monitoring health, disease and physi- by their accrediting organizations as well. ological state, and for establishing identity. During these inspections, procedures and Some common blood tests include com- documentation are checked. plete blood count, blood smear, glucose tolerance, basic metabolic profile and lipid Reference Range profile. Blood or other body fluids also What is “normal?” When your doctor re- may be tested for the presence of specific ceives a result from a diagnostic test, he or antibodies or antigens. Blood usually is she must interpret the results. A result that collected by a doctor, nurse or specially is normal for one person could indicate a trained phlebotomist. Depending on the problem for another. Results of many diag- type of blood tests needed, blood first must nostic tests vary according to the patient’s be processed in various ways. An anti-co- age, gender, recently eaten foods, whether agulant often is added to prevent clotting. he/she is exercising or resting and other Centrifugation is used to separate blood factors. Therefore, the “normal” range is cells from the serum. Automation allows not the same for all patients. Results also for fast, accurate testing of large numbers can vary depending on the procedures of samples. Advances in technology mean followed and the equipment used, so it that smaller volumes of blood can be used is important to interpret test results in the context of the lab where the test was performed. A reference range is determined for a particular population (such as pregnant women or healthy men between ages 65 and 70) by averaging the test results for a large number of people and add- ing/subtracting two standard deviations to/from the average. Good practice is for the laboratory to provide a reference range of “normal” results for the particular test and laboratory and for In This Image: Blood analyzing instruments the doctor to interpret the results image by: Bobjgalindo / Wikipedia for the particular patient. Pathology & Forensic Science: Diagnostic Services in Health Care 6 to provide accurate results. And while a could be making a patient sick in order to variety of laboratory machines do the dif- identify the microorganism and determine ferent blood tests, humans still are needed what type of antibiotics will provide ef- to ensure the machines function properly fective treatment. The patient specimen and the results are interpreted correctly. might be a throat swab, a stool sample, Finally, blood always should be treated as a urine, blood, sputum from a cough or pus potential biological hazard. from a wound. The patient specimen is placed on a nutrient media and incubated Urinalysis at a specific temperature for 18 to 24 hours. Urinalysis refers to a group of tests done A lab technician examines the plate and on urine to detect urinary tract infections, performs further tests to identify any metabolic disorders (such as diabetes) and bacteria or fungi growing on it. Healthy kidney disorders. A urinalysis includes up people have many normal bacteria in their to three steps. First, the urine is inspected digestive tracts and on their skin that do visually. It should be pale yellow and clear. not cause harm. In fact, some are helpful Cloudy urine might indicate an infection, and necessary for good health. Therefore, while dark urine might indicate blood. it is important to distinguish nonharmful Second, a series of chemical tests are per- organisms from pathogenic ones. If the or- formed, usually using chemical test strips. ganism is pathogenic, the lab also can test These indicate the concentration of the to see which antibiotics are effective. urine, the pH of the urine and the presence of protein, glucose, ketones and several Biopsy other substances that shouldn’t be in the In a biopsy, a sample of tissue is removed urine. Third, if abnormal results are found, from the body to determine the presence a microscopic examination of the urine and progression of a disease or disorder. is done to look for cells, microorganisms Some biopsies require surgery, while oth- and crystals. Other urine tests also may ers use a needle to remove the sample be performed depending on the results of while a doctor palpitates the lump or uses these tests and other conditions the pa- X-ray or ultrasound imaging to guide the tient may have.

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