Mosby’s diagnostic and laboratory test reference 14th edition

Variations in any area of the test e.g., patient preparation, test procedure, normal values, postproce-dural care can be noted here.. contents Routine blood testing, inside front cover R

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ROUTINE BLOOD TESTING

Many laboratory tests include the direction to perform routine blood testing The protocol for those tests is presented here and is cross- referenced within the many tests requiring them.

Before

• Follow proper patient identification protocols to avoid wrong patient events Usually name and date of birth are used as two identifiers Explain the procedure to the patient.

Tell the patient if fasting is necessary (Fasting is most commonly required with glucose and lipid studies.)

If fasting is required, instruct the patient not to consume any food or fluids Only water is permitted Fasting requirements usually vary from

After

• Apply pressure or a pressure dressing to the venipuncture site.

• Assess the site for bleeding.

= Patient teaching

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ROUTINE URINE TESTING

Many laboratory tests include the direction to perform routine urine testing The protocol for those tests is presented here and is cross- referenced within the many tests requiring them.

Before

• Follow proper patient identification protocols to avoid wrong patient events Usually, name and date of birth are used as two identifiers Explain the procedure to the patient.

Inform the patient if food or fluid restrictions are needed.

During

Random, fresh, or spot specimen

Instruct the patient to urinate into an appropriate nonsterile container.

24-hour specimen

1 Begin the 24-hour collection by discarding the first specimen.

2 Collect all urine voided during the next 24 hours.

3 Show the patient where to store the urine.

4 Keep the urine on ice or refrigerated during the collection period Foley bags are kept in a basin of ice Some collections require a preservative Check with the laboratory.

5 Post the hours for the urine collection in a prominent place to prevent accidentally discarding a specimen.

6 Instruct the patient to void before defecating so that urine is not contaminated by stool.

7 Remind the patient not to put toilet paper in the urine collection container.

8 Collect the last specimen as close as possible to the end of the 24-hour period Add this urine to the collection.

After

• Transport the specimen promptly to the laboratory.

= Patient teaching

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COMMON REFERENCE RANGES

FOR HEALTHY ADULTS

(NOTE: These values are generalizations Each laboratory has specific ranges.)

RBC: 4.7 – 6.1 × 10 6 /µL; 4.2-5.4 × 10 6 /µL 770 Hemoglobin: 14-18 g/dL; 12-16 g/dL 488 Hematocrit: 40%-52%; 36%-47% 485

Prothrombin time (PT): 11-12.5 sec 753 International normalized ratio (INR): 0.8-1.1 753 Activated partial thromboplastin time (APTT): 30-40 sec 681 Glycosylated hemoglobin: 4%-5.9% 471

Electrolytes and Gastrointestinal, Renal, and

Liver Function

Sodium: 136-145 mEq/L 835 Potassium: 3.5-5 mEq/L 724 Chloride: 98-106 mEq/L 233

Blood urea nitrogen (BUN): 10-20 mg/dL 155 Creatinine: 0.5-1.1 mg/dL 301 Glucose: 74-106 mg/dL 462 Calcium: 9-10.5 mg/dL 189

Lipase: 0-160 U/L 562 Protein (total): 6.4-8.3 g/dL 476 Albumin: 3.5-5 g/dL 476 Bilirubin (total): 0.3-1 mg/dL 137 Bilirubin (direct): 0.1-0.3 mg/dL 137

Aspartate aminotransferase (AST): 0-35 U/L 125 Gamma-glutamyl transpeptidase (GGT): 8-38 U/L 435

Lipids

Triglycerides: 40-180 mg/dL 908

High-density lipoproteins (HDL): > 45 mg/dL; > 55 mg/dL 565 Low-density lipoproteins (LDL): < 130 mg/dL 565

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MOSBY’S

DIAGNOSTIC AND LABORATORY TEST REFERENCE

Timothy J Pagana, MD, FACS

Medical Director Emeritus

The Kathryn Candor Lundy Breast Health Center

Susquehanna Health System

Williamsport, Pennsylvania

Theresa Noel Pagana, MD, FAAEM

Emergency Medicine Physician

Virtua Voorhees Hospital

Voorhees, New Jersey

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3251 Riverport Lane

St Louis, Missouri 63043

MOSBY'S DIAGNOSTIC AND LABORATORY

TEST REFERENCE, FOURTEENTH EDITION ISBN: 978-0-323-60969-2

Copyright © 2019 by Elsevier, Inc All rights reserved.

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or from any use or operation of any methods, products, instructions, or ideas contained in the material herein.

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With love and adoration,

we dedicate this book to our grandchildren:

Ella Marie Gaul

Jocelyn Elizabeth Gaul

Timothy William Gaul

Justin Aquinas Gaul

Juliana Kathleen Pericci

Luke Michael Pericci

John Henry Bullen V

Hunter Timothy Bullen

The Prince William County

School of Practical Nursing

Flora Sayson

Instructor, Nursing College of Southern Nevada Las Vegas, Nevada

Jessica Massengill, MHA-Edu, BSN, RN

Coordinator of Health Sciences

Tennessee College of Applied Technology-Harriman Harriman, Tennessee

Shopha Tserotas, MS, RN

Coordinator, Weekend Program

Assistant Clinical Professor Texas Woman's University Dallas, Texas

iv

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of health-care providers to ensure that the tests are accurately and safely performed Use of this guide should eliminate the need for test repetition resulting from problems with patient prepara-tion, test procedures, or collection techniques Information on radiation exposure and risks has been added Every feature of this book is designed to provide pertinent information in a sequence that best simulates priorities in the clinical setting.

The following information is provided, wherever applicable, for effective diagnostic and laboratory testing:

• Name of test Tests are listed by their complete names A

complete list of abbreviations and alternate test names follows each main entry

• Type of test This section identifies whether the test is, for

example, an x-ray procedure, ultrasound, nuclear scan, blood test, urine test, sputum test, or microscopic examination of tissue This section helps the reader identify the source of the laboratory specimen or location of the diagnostic procedure

• Normal findings Where applicable, normal values are listed for

the infant, child, adult, and elderly person Also, where priate, values are separated into male and female It is impor-tant to realize that normal ranges of laboratory tests vary from institution to institution This variability is even more obvious among the various laboratory textbooks For this reason, we have deliberately chosen not to add a table of normal values

appro-as an appendix, and we encourage the user to check the mal values at the institution where the test is performed This should be relatively easy because laboratory reports include nor-mal values Results are given in both conventional units and the International System of Units (SI units) where possible

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vi preface

• Possible critical values These values give an indication of

results that are well outside the normal range These results require health-care provider notification and usually result in some type of intervention The Joint Commission is looking

at the timely and reliable communication of critical laboratory values as one of its patient safety goals

• Test explanation and related physiology This section

pro-vides a concise yet comprehensive description of each test It includes fundamental information about the test itself, spe-cific indications for the test, how the test is performed, what disease or disorder the various results may show, how it will affect the patient or client, and relevant pathophysiology that will enhance understanding of the test

• Contraindications These data are crucial because they alert

health-care providers to patients to whom the test should not be administered Patients highlighted in this section fre-quently include those who are pregnant, are allergic to iodin-ated or contrast dyes, or have bleeding disorders

• Potential complications This section alerts the user to

potential problems that necessitate astute assessments and interventions For example, if a potential complication is renal failure, the implication may be to hydrate the patient before the test and force fluids after the test A typical potential com-plication for many x-ray procedures is allergy to iodinated dye Patient symptoms and appropriate interventions are described

in detail

• Interfering factors This section contains pertinent

informa-tion because many factors can invalidate the test or make the test results unreliable An important feature is the inclusion of drugs that can interfere with test results Drugs that increase

or decrease test values are always listed at the end of this tion for consistency and quick access A drug symbol ( ) is used to emphasize these drug interferences

sec-• Procedure and patient care This section emphasizes the

role of nurses and other health-care providers in diagnostic and laboratory testing by addressing psychosocial and physi-ologic interventions Patient teaching priorities are noted with a special icon ( ) to highlight information to be com-municated to patients For quick access to essential informa-tion, this section is divided into before, during, and after time sequences

◦ Before This section addresses the need to explain the

pro-cedure and to allay patient concerns or anxieties If patient consent is usually required, this is listed as a bulleted item

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preface vii

Other important features include requirements such as fasting, obtaining baseline values, and performing bowel preparations Radiation risk is addressed with x-rays and nuclear medicine studies

◦ During This section gives specific directions for

clinical specimen studies (e.g., urine and blood ies) Diagnostic procedures and their variations are described in a numbered, usually in a step-by-step for-mat Important information, such as who performs the test, where the study is performed, patient sensation, and duration of the procedure, is bulleted for emphasis The duration of the procedure is very helpful for patient teaching because it indicates the time generally allotted for each study

stud-◦ After This section includes vital information that the

nurse or other health-care provider should heed or convey after the test Examples include such factors as maintaining bed rest, comparing pulses with baseline values, encourag-ing fluid intake, and observing the patient for signs and symptoms of sepsis

• Abnormal findings As the name implies, this section lists

the abnormal findings for each study Diseases or conditions that may be indicated by increased ( ) or decreased ( ) val-ues are listed where appropriate

• Notes This blank space at the end of the tests facilitates

indi-vidualizing the studies according to the institution at which the test is performed Variations in any area of the test (e.g., patient preparation, test procedure, normal values, postproce-dural care) can be noted here

This logical format emphasizes clinically relevant tion The clarity of this format allows for quick understanding

informa-of content essential to both students and health-care ers Color has been used to help locate tests and to highlight critical information (e.g., possible critical values) Color is also used in the illustrations to enhance the reader’s understanding

provid-of many diagnostic procedures (e.g., bronchoscopy, fetoscopy, endoscopic retrograde cholangiopancreatography [ERCP], peri-cardiocentesis, transesophageal echocardiography [TEE]) Many tables are used to simplify complex material on such topics as bioterrorism infectious agents, blood collection tubes, hepatitis testing, and protein electrophoresis Extensive cross-referencing exists throughout the book, which facilitates understanding and helps the user tie together or locate related studies, such as hemoglobin and hematocrit

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viii preface

Standard guidelines for routine blood and urine testing are located on the inside front cover for easy access A list of abbre-viations for test names is included on the book’s endpapers

Appendix A includes a list of studies according to body system

This list may familiarize the user with other related studies the patient or client may need or the user may want to review This should be especially useful for students and health-care providers working in specialized areas

Appendix B provides a list of studies according to test type

This list may help the user read and learn about similarly formed tests and procedures (e.g., barium enema and barium swallow)

per-Appendix C provides a list of blood tests used for disease and organ panels.

Appendix D provides a list of symbols and units of measurement

Finally, a comprehensive index includes the names of all tests, their synonyms and abbreviations, and any other relevant terms found in the tests

New to this edition is a table of Common Reference Ranges added to the inside front cover This adds to the user-friendly aspect of this book by quickly identifying common reference ranges This is a good starting point for students and a quick reference for routine lab values However, because lab values vary from institution to institution, be sure to use the normal values

of the lab performing the test

Many new studies, such as alpha defensin, ceramides, and small intestinal bacterial overgrowth tests, have been added All other studies have been revised and updated Outdated studies have been eliminated

We sincerely thank our editors for their enthusiasm and tinued support We are most grateful to the many nurses and other health-care providers who made the first 13 editions of this book so successful Thank you so much This success vali-dated the need for a user-friendly and quick-reference approach

con-to laboracon-tory and diagnostic testing

We sincerely invite additional comments from current users

of this book so that we may continue to provide useful, relevant diagnostic and laboratory test information to users of future editions

Kathleen D Pagana Timothy J Pagana Theresa N Pagana

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contents

Routine blood testing, inside front cover

Routine urine testing, inside front cover

Common reference ranges, inside front cover

Appendix A: List of tests by body system, 988

Appendix B: List of tests by type, 1000

Appendix C: Disease and organ panels, 1011

Appendix D: Symbols and units of measurement, 1015

Figure 5 Bilirubin metabolism and excretion, 138

Figure 6 Bone marrow aspiration, 163

Figure 7 Bronchoscopy, 185

Figure 8 Cardiac catheterization, 204

Figure 9 Chorionic villus sampling, 242

Figure 10 Hemostasis and fibrinolysis, 251

Figure 11 Colposcopy, 262

Figure 12 Cardiac enzymes after myocardial infarction, 298

Figure 13 Cystoscopic examination of the male bladder, 309

Figure 14 Ureteral catheterization through the cystoscope, 310

Figure 15 Disseminated intravascular coagulation, 331

Figure 16 Ductoscopy, 337

Figure 17 ECG planes of reference, 343

Figure 18 Electrocardiography, 344

Figure 19 Endoscopic retrograde cholangiopancreatography, 366

Figure 20 Esophageal function studies, 380

Figure 26 Liver biopsy, 571

Figure 27 Lumbar puncture, 581

Figure 28 Transbronchial needle biopsy, 585

Figure 29 Stereotactic breast biopsy, 607

Figure 30 Oximetry, 659

Figure 31 Papanicolaou (Pap) smear, 669

Figure 32 Paracentesis, 672

Figure 33 Pericardiocentesis, 690

Figure 34 Rectal ultrasonography, 741

Figure 35 Lung volumes and capacities, 760

Figure 36 Renal biopsy, 777

Figure 37 Renovascular hypertension, 784

Figure 38 Rectal culture of the female, 816

Figure 39 Urethral culture of the male, 817

Figure 40 Thoracentesis, 865

Figure 41 Fibrin clot formation, 875

Figure 42 Transesophageal echocardiography, 904

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user’s guide to test preparation and procedures

Health-care economics demands that laboratory and diagnostic testing be performed accurately and in the least amount of time possible Tests should not have to be repeated because of improper patient preparation, test procedure, or specimen col-lection technique Patient identification protocols should be fol-lowed to avoid wrong patient events Two patient identifiers, such as name and date of birth, are usually used The following guidelines delineate the responsibilities of health-care providers

to ensure safety of test procedures and accuracy of test results Guidelines are described for the following major types of tests: blood, urine, stool, x-ray, nuclear scanning, ultrasound, and endoscopy

Blood tests

Overview

Blood studies are used to assess a multitude of body processes and disorders Common studies include enzymes, serum lipids, electrolyte levels, red and white blood cell counts, clotting fac-tors, hormone levels, and levels of breakdown products (e.g., blood urea nitrogen)

Multiphasic screening machines can perform many blood tests

simultaneously using a very small blood sample The advantages

of using these machines are that results are available quickly and the cost is lower when compared with individually performing each test

Appendix C provides a list of current disease and organ panels For example, the basic metabolic panel and the com-prehensive metabolic panel have replaced the Chem-7 and Chem-12 panels These changes are the result of federal guidelines that have standardized the nomenclature for chem-istry panels

Guidelines

• Observe universal precautions when collecting a blood specimen

• Check whether fasting is required Many studies, such as ing blood sugar and cholesterol levels, require fasting for a designated period of time Water is permitted

fast-• If ordered, withhold medications until the blood is drawn

• Record the time of day when the blood test is drawn Some blood test results (e.g., those for cortisol) vary according to

a diurnal pattern, and this must be considered when blood levels are interpreted

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xii user’s guide to test preparation and procedures

• In general, two or three blood tests can be done per tube of blood collected (e.g., two or three chemistry tests from one red-top tube of blood)

• Note the patient’s position for certain tests (e.g., renin, because levels are affected by body position)

• Collect the blood in a properly color-coded test tube Blood collection tubes have color-coded stoppers to indicate the presence or absence of different types of additives (preserva-tives and anticoagulants) A preservative prevents change in the specimen, and an anticoagulant inhibits clot formation or coagulation Charts are available from the laboratory indicat-ing the type of tube needed for each particular blood test A representative chart is shown in Table A, p xiv

• Follow the recommended order of draw when collecting

blood in tubes Draw specimens into nonadditive (e.g., top) tubes before drawing them into tubes with additives This prevents contamination of the blood specimen with additives that may cause incorrect test results Fill the tubes in the following order:

red-1 Blood culture tubes (to maintain sterility)

2 Nonadditive tubes (e.g., red-top)

3 Coagulation tubes (e.g., blue-top)

4 Heparin tubes (e.g., green-top)

5 Ethylenediaminetetraacetic acid (EDTA) tubes (e.g., lavender-top)

6 Oxalate/fluoride tubes (e.g., gray-top)

• To obtain valid results, do not fasten the tourniquet for ger than 1 minute Prolonged tourniquet application can cause stasis and hemoconcentration

lon-• Collect the blood specimen from the arm without an venous (IV) device, if possible IV infusion can influence test results

intra-• Do not use the arm bearing a dialysis arteriovenous fistula for venipuncture unless the physician specifically authorizes it

• Because of the risk of cellulitis, do not take specimens from the side on which a mastectomy or axillary lymph node dissec-tion was performed

• Follow the unit guidelines for drawing blood from an ing venous catheter (e.g., a triple-lumen catheter) Guidelines will specify the amount of blood to be drawn from the cath-eter and discarded before blood is collected for laboratory studies The guidelines will also indicate the amount and type

indwell-of solution needed to flush the catheter after drawing the blood to prevent clotting

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TABLE A Common blood collection tubes

Separates the serum for testing ChemistryBilirubin

Blood urea nitrogen

gel for serum separator

Serum separator tube for serum determinatives in chemistry and serology

Chemistry, serology

Royal blue Heparin/EDTA Provides low levels of trace elements Trace metals, toxicology

CBC

Glucose

plasma needs to be tested ChemistryAmmoniaBlue (light) Sodium citrate Prevents blood from clotting when

plasma needs to be tested Prothrombin timePartial thromboplastin timeBlack Sodium citrate Binds calcium to prevent blood clotting Westergren ESR

CBC, Complete blood count; EDTA, ethylenediaminetetraacetic acid; ESR, erythrocyte sedimentation rate.

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xiv user’s guide to test preparation and procedures

• Do not shake the blood specimen Hemolysis may result from vigorous shaking and can invalidate test results Use gentle inversions

• Collect blood cultures before the initiation of antibiotic

therapy Blood cultures are often drawn when the patient manifests a fever Often two or three cultures are taken at 30-minute intervals from different venipuncture sites

• Skin punctures can be used for blood tests on capillary blood

Common puncture sites include the fingertips, earlobes, and heel surfaces Fingertips are often used for small children, and the heel is the most commonly used site for infants

• Ensure that the blood tubes are correctly labeled and ered to the laboratory

deliv-• After the specimen is drawn, apply pressure or a sure dressing to the venipuncture site Assess the site for bleeding

pres-• If the patient fasted before the blood test, reinstitute the priate diet

appro-Urine tests

Overview

Urine tests are easy to obtain and provide valuable information about many body system functions (e.g., kidney function, glu-cose metabolism, and various hormone levels) The ability of the patient to collect specimens appropriately should be assessed to determine the need for assistance

Guidelines

• Observe universal precautions in collecting a urine specimen

• Use the first morning specimen for routine urinalysis because

it is more concentrated To collect a first morning specimen, have the patient void before going to bed and collect the first urine specimen immediately upon rising

• Random urine specimens can be collected at any time They

are usually obtained during daytime hours and without any prior patient preparation

• If a culture and sensitivity (C&S) study is required or if the

specimen is likely to be contaminated by vaginal discharge or

bleeding, collect a clean-catch or midstream specimen This

requires meticulous cleansing of the urinary meatus with an antiseptic preparation to reduce contamination of the speci-men by external organisms Then the cleansing agent must be completely removed because it may contaminate the speci-

men Obtain the midstream collection by doing the following:

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user’s guide to test preparation and procedures xv

1 Have the patient begin to urinate in a bedpan, urinal, or toilet and then stop urinating (This washes the urine out

of the distal urethra.)

2 Correctly position a sterile urine container and have the patient void 3 to 4 oz of urine into it

3 Cap the container

4 Allow the patient to finish voiding

• One-time composite urine specimens are collected over a

period that may range anywhere from 2 to 24 hours To lect a timed specimen, instruct the patient to void and discard

col-the first specimen This is noted as col-the start time of col-the test

Instruct the patient to save all subsequent urine in a special container for the designated period Remind the patient to void before defecating so that urine is not contaminated by feces Also, instruct the patient not to put toilet paper in the collection container A preservative is usually used in the col-lection container At the end of the specified time period, have the patient void and then add this urine to the specimen con-tainer, thus completing the collection process

• Collection containers for 24-hour urine specimens should hold

3 to 4 L of urine and have tight-fitting lids They should be labeled with the patient’s name, the starting collection date and time, the ending collection date and time, the name of the test, the preservative, and storage requirements during collection

• Many urine collections require preservatives to maintain their stability during the collection period Some specimens are best preserved by being kept on ice or refrigerated

• Urinary catheterization may be needed for patients who are

unable to void This procedure is not preferred because of patient discomfort and the risk of patient infection

• For patients with an indwelling urinary catheter, obtain a

specimen by aseptically inserting a needleless syringe into the catheter at a drainage port distal to the sleeve leading to the balloon Aspirate urine and then place it in a sterile urine con-tainer The urine that accumulates in the plastic reservoir bag should never be used for a urine test

• Urine specimens from infants and young children are usually

collected in a disposable pouch called a U bag This bag has an

adhesive backing around the opening to attach to the child’s perineum After the bag is in place, check the child every 15 minutes to see if an adequate specimen has been collected Remove the specimen as soon as possible after the collection and then label it and transport it to the laboratory

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xvi user’s guide to test preparation and procedures

Stool tests

Overview

The examination of feces provides important information that aids in the differential diagnosis of various gastrointestinal dis-orders Fecal studies may also be used for microbiologic studies, chemical determinations, and parasitic examinations

Guidelines

• Observe universal precautions in collecting a stool specimen

• Collect stool specimens in a clean container with a fitted lid

• Do not mix urine and toilet paper with the stool specimen Both can contaminate the specimen and alter the results

• Fecal analysis for occult blood, white blood cells, or tive fecal fat requires only a small amount of a randomly col-lected specimen

qualita-• Quantitative tests for daily fecal excretion of a particular stance require a minimum of a 3-day fecal collection This col-lection is necessary because the daily excretion of feces does not correlate well with the amount of food ingested by the patient in the same 24-hour period Refrigerate specimens or keep them on ice during the collection period Collect stool

sub-in a 1-gallon contasub-iner

• A small amount of fecal blood that is not visually apparent is

termed occult blood Chemical tests using commercially

pre-pared slides are routinely used to detect fecal blood Numerous commercial slide tests use guaiac as the indicator These guaiac tests are routinely done on nursing units and in medical offices

• Consider various factors (e.g., other diagnostic tests and medications) in planning the stool collection For example, if the patient is scheduled for x-ray studies with barium sulfate, collect the stool specimen first Various medications (e.g., tet-racyclines and antidiarrheal preparations) affect the detection

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user’s guide to test preparation and procedures xvii

dye-enhanced cardiac catheterization With the concern about radiation exposure, it is important to realize that the patient may question if the proposed benefits outweigh the risks involved

Radiation dose

There are several units used to quantify amount of tion absorbed from diagnostic imaging tests The gray (Gy) is the measure of the amount of energy absorbed per unit mass Because different organs in the body absorb radiation differently, the sievert (Sv) is often used instead of the gray The sievert is the biological effect of 1 gray of radiation on human body tis-sue The sievert is more helpful in comparing radiation exposure

radia-to different parts of the body Radiation doses in medical ing are typically measured in millisieverts (mSv) or 1/1000 of a sievert On average, each person receives about 3 mSv of radia-tion yearly from natural background radiation

imag-The roentgen equivalent in man (rem) is an older unit to quantify the amount of radiation absorbed from x-rays 1 rem is equivalent to 0.01 sievert

See chart below for average amounts of radiation for adults associated with diagnostic testing

expo-The cumulative radiation dose from diagnostic imaging is very small and the benefit of proper diagnosis and treatment of disease generally outweighs the risks However each patient’s current sit-uation and history of radiation must be considered to accurately assess cumulative risks and benefits Diagnostic procedures with higher radiation doses (e.g., computed tomography [CT] scans) should be clearly justified Appropriateness Criteria published by the American College of Radiology (acr.org) is helpful in justifi-cation of performance of x-ray imaging

Special consideration should be given to pregnant women and children before ordering x-ray imaging because the effects

of radiation are more profound in fetuses and young children

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xviii user’s guide to test preparation and procedures

If a woman is pregnant, the risks versus benefits must be fully considered Certain studies with low radiation in which the focus of radiation is not on the fetus are obviously safer (Lead-containing shields can reduce x-ray exposure to fetuses.) Imaging using higher dose of radiation should be given only if the risk of not making the diagnosis is greater than the radiation risk.Radiation risks are most significant in early fetal period and are less significant as the pregnancy progresses

care-Patients with high body mass indexes should also be given extra consideration before ordering imaging studies These patients often require greater radiation doses to penetrate body thickness to create acceptable images Nuclear medicines studies are not affected in the same way Although the x-ray exposure needed to produce one fluoroscopic image is low (compared with radiography), high exposures to patients can result from the time that may be encountered in fluoroscopic procedures

Radiation Associated with Diagnostic Testing

user’s guide to test preparation and procedures xix Common CT imaging

Cardiac nuclear stress testing 20-40

Gastric emptying scan 0.4

Cardiac catheterization (diagnostic) 7

Coronary angiogram (stent) 15

Endoscopic retrograde

cholangiopancreatography (ERCP) 4

Fluoroscopic Barium Swallow 1.5

Head and neck angiogram 5

Positron emission tomography

xx user’s guide to test preparation and procedures

Guidelines

• Assess the patient for any similar or recent x-ray procedures

• Evaluate the patient for allergies to iodine dye Carefully

con-sider the following points:

1 Many types of contrast media are used in radiographic studies For example, organic iodides and iodized oils are frequently used

2 Allergic reactions to iodinated dye may vary from mild flushing, itching, and urticaria to severe, life-threatening anaphylaxis (evidenced by respiratory distress, drop in blood pressure, or shock) In the unusual event of ana-phylaxis, the patient is treated with diphenhydramine (Benadryl), steroids, and epinephrine Oxygen and endo-tracheal equipment should be on hand for immediate use

3 The patient should always be assessed for allergies to iodine dye before it is administered Inform the radiolo-gist if an allergy to iodinated contrast is suspected The radiologist may prescribe Benadryl and steroid preparation

to be administered before testing Usually, hypoallergenic nonionic contrast will be administered to allergic patients during the test

4 After the x-ray procedure, evaluate the patient for a delayed reaction to dye (e.g., dyspnea, rashes, tachycardia, hives) This usually occurs within 2 to 6 hours after the test Treat with antihistamines or steroids

• Assess the patient for any evidence of dehydration or renal disease Usually BUN and creatinine tests are obtained before administration of iodine-containing IV contrast Hydration may be required before the administration of iodine

• Assess the patient for diabetes People with diabetes are ticularly susceptible to renal disease caused by the administra-tion of iodine-containing IV contrast Patients with diabetes who take metformin (Glucophage) or glyburide (Micronase) are particularly susceptible to lactic acidosis and hypoglyce-mia These medications may be discontinued for 1 to 4 days before and 1 to 2  days after the administration of iodine Check with the x-ray department

par-• Women in their childbearing years should have x-ray tions during menses or within 10 to 14 days after the onset of menses to avoid possible exposure to a fetus

examina-• Pregnant women should not have x-ray procedures unless the benefits outweigh the risk of damage to the fetus

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user’s guide to test preparation and procedures xxi

• Note whether other x-ray studies are being planned; schedule them in the appropriate sequence For example, x-ray exami-nations that do not require contrast should precede exami-nations that do require contrast X-ray studies with barium should be scheduled after ultrasonography

• Note the necessary dietary restrictions Such studies as barium enema and intravenous pyelogram (IVP) are more accurate if the patient is kept NPO (fasting from food and liquids) for several hours before the test

• Determine whether bowel preparations are necessary For example, barium enemas and IVPs require bowel-cleansing regimens

• Determine whether signed consent forms are required These are necessary for most invasive x-ray procedures

• Remove metal objects (e.g., necklaces, watches) because they can hinder visualization of the x-ray field

• Patient aftercare is determined by the type of x-ray dure For example, a patient having a simple chest x-ray study will not require postprocedure care However, invasive x-ray procedures involving contrast dyes (e.g., cardiac catheteriza-tion) require extensive nursing measures to detect potential complications

proce-Nuclear scanning

Overview

With the administration of a radionuclide and subsequent surement of the radiation of a particular organ, functional abnormalities of various body areas (e.g., brain, heart, lung, bones) can be detected Because the half-lives of the radioisotopes are short, only minimal radiation exposure occurs (See p xx)

mea-Guidelines

• Radiopharmaceuticals concentrate in target organs by various mechanisms For example, some labeled compounds (e.g., hippuran) are cleared from the blood and excreted by the kid-neys Some phosphate compounds concentrate in the bone and infarcted tissue Lung function can be studied by imaging the distribution of inhaled gases or aerosols

• Note whether the patient has had any recent exposure to radionuclides The previous study could interfere with the interpretation of the current study

• Note the patient’s age and current weight This information

is used to calculate the dose of radioactive substances

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xxii user’s guide to test preparation and procedures

• Nuclear scans are contraindicated in pregnant women and nursing mothers

• Many scanning procedures do not require special tion However, a few have special requirements For example, for bone scanning, the patient is encouraged to drink sev-eral glasses of water between the time of the injection of the isotope and the actual scanning For some studies, blocking agents may need to be given to prevent other organs from taking up the isotope

prepara-• For most nuclear scans, a small amount of an organ-specific radionuclide is given orally or injected intravenously After the radioisotope concentrates in the desired area, the area is scanned The scanning procedure usually takes place in the nuclear medicine department

• Instruct the patient to lie still during the scanning

• Usually encourage the patient to drink extra fluids to enhance excretion of the radionuclide after the test is finished

• Although the amount of radionuclide excreted in the urine is very low, rubber gloves are sometimes recommended if the urine must be handled Some hospitals may advise the patient

to flush the toilet several times after voiding

Ultrasound studies

Overview

In diagnostic ultrasonography, harmless high-frequency sound waves are emitted and penetrate the organ being studied The sound waves bounce back to the sensor and are electronically converted into a picture of the organ Ultrasonography is used

to assess a variety of body areas, including the pelvis, abdomen, breast, heart, and pregnant uterus

exami-• Ultrasound examinations are usually performed in an sound room; however, they can be performed in the patient unit

ultra-• For ultrasound, a greasy paste is applied to the skin ing the desired organ This paste is used to enhance sound transmission and reception because air impedes transmission

overly-of sound waves to the body

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user’s guide to test preparation and procedures xxiii

• Because of the noninvasive nature of ultrasonography, no cial measures are needed after the study except for helping the patient remove the ultrasound paste

spe-• Ultrasound examinations have no radiation risk

• Ultrasound examinations can be repeated as many times as necessary without being harmful to the patient No cumula-tive effect has been seen

• Barium has an adverse effect on the quality of abdominal studies For this reason, schedule ultrasound of the abdomen before barium studies

• Large amounts of gas in the bowel obstruct visualization of the bowel This is because bowel gas is a reflector of sound

Endoscopy procedures

Overview

With the help of a lighted, flexible instrument, internal structures

of many areas of the body (e.g., stomach, colon, joints, bronchi, urinary system, and biliary tree) can be directly viewed The spe-cific purpose and procedure should be reviewed with the patient

Guidelines

• Preparation for an endoscopic procedure varies according to the internal structure being examined For example, examina-tion of the stomach (gastroscopy) will require the passage of an instrument through the esophagus and into the stomach The patient is kept NPO for 8 to 12 hours before the test to pre-vent gagging, vomiting, and aspiration For colonoscopy, an instrument is passed through the rectum and into the colon Therefore, the bowel must be cleansed and free of fecal mate-rial to afford proper visualization Arthroscopic examination of the knee joint is usually done with the patient under general anesthesia, which necessitates routine preoperative care

• Schedule endoscopic examinations before barium studies

• Obtain a signed consent for endoscopic procedures

• Endoscopic procedures are preferably performed by a cian in a specially equipped endoscopy room or in an operat-ing room However, some kinds can safely be performed at the bedside

physi-• Air is instilled into the bowel during colon examinations to maintain patency of the bowel lumen and to afford better visualization This sometimes causes gas pains

• In addition to visualization of the desired area, special cedures can be performed Biopsies can be obtained, and bleeding ulcers can be cauterized Also, knee surgery can be performed during arthroscopy

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xxiv user’s guide to test preparation and procedures

• Specific postprocedure interventions are determined by the type of endoscopic examination performed All procedures have the potential complication of perforation and bleeding Most procedures use some type of sedation; safety precau-tions should be observed until the effects of the sedatives have worn off

• After colonoscopy and similar studies, the patient may plain of rectal discomfort A warm tub bath may be soothing

com-• Usually keep the patient NPO for 2 hours after endoscopic procedures of the upper gastrointestinal system Be certain that swallow, gag, and cough reflexes are present before per-mitting fluids or liquids to be ingested orally

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abdominal ultrasound 1

A

Type of test Ultrasound

Normal findings

Normal abdominal aorta, liver, gallbladder, bile ducts, pancreas, kidneys, ureters, and bladder

Test explanation and related physiology

Ultrasonography provides accurate visualization of the abdominal aorta, liver, gallbladder, pancreas, bile ducts, kidneys, ureters, and bladder Real-time ultrasound provides an accurate picture of the organ being studied (Figure 1)

The kidney is ultrasonographically evaluated to diagnose

and locate renal cysts, to differentiate renal cysts from solid renal tumors, to demonstrate renal and pelvic calculi, to docu-ment hydronephrosis, to guide a percutaneously inserted needle for cyst aspiration or biopsy, and to place a nephrostomy tube Ultrasound of the urologic tract is also used to detect malformed

or ectopic kidneys and perinephric abscesses Renal tion surveillance is possible with ultrasound

transplanta-Endourethral urologic ultrasound can also be performed

through a stent that has a transducer at its end The stent probe can be advanced into the bladder where the depth of a tumor into the bladder wall can be measured In the ureter, stones, tumors, or extraurethral compression can be identified and localized Finally,

in the proximal ureter, renal tumors or cysts can be delineated

One of the most common uses of ultrasound is the ment of post void urinary bladder residual This is a measure-ment of the amount of urine after micturition This test can be easily performed at the bedside or in doctor’s office with a por-table ultrasound unit

measure-Pelvic, obstetric, prostate, and testes ultrasound are discussed

gallbladder and bile ducts can be visualized and examined for dence of gallstones, polyps, or bile duct dilation The pancreas is

evi-examined for evidence of tumors, pseudocysts, acute tion, chronic inflammation, or pancreatic abscesses Because this

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2 abdominal ultrasound

study requires no contrast material and has no associated tion, it is especially useful in patients who are allergic to contrast, have diminished renal function, or are pregnant Fasting may be preferred, but it is not mandatory

radia-Interfering factors

• Barium blocks transmission of ultrasonic waves For this son, ultrasonography of the abdomen should be performed before any barium contrast studies

rea-• Large amounts of gas in the bowel distort visualization of abdominal organs because bowel gas reflects sound Likewise, ultrasonic evaluation of the lungs yields poor results

• Obesity may affect the results of the study because sound waves are altered by fatty tissue

• The quality of the ultrasound image and the sufficiency of the study depend to a very large part on the abilities of the ultra-sound technologist performing the study

FIG. 1 Ultrasound of the abdomen

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abdominal ultrasound 3

A

Procedure and patient care

Before

Explain the procedure to the patient

Tell the patient that fasting may or may not be required, depending on the organ to be examined No fasting is required for ultrasonography of the abdominal aorta, kidney, liver, spleen, or pancreas Fasting, however, is preferred for ultrasound of the gallbladder and bile ducts

During

• Note the following procedural steps:

1 The patient is placed on the ultrasonography table in the prone or supine position, depending on the organ to be studied

2 A greasy conductive paste (coupling agent) is applied to the patient’s skin This paste is used to enhance sound wave transmission and reception

3 A transducer is placed over the skin

4 Pictures are taken of the reflections from the organs

• The test is completed in about 1 hour, usually by an sound technologist, and is interpreted by a radiologist

Tell the patient that this procedure causes no discomfort

After

• Remove the coupling agent from the patient’s skin

• Note that if a biopsy is done, refer to biopsy of the specific organ (e.g., liver or kidney biopsy)

acetylcholine receptor antibody panel 5

ACh receptor (muscle) binding antibodies: ≤ 0.02 nmol/L

ACh receptor (muscle) modulating antibodies: 0%-20% (reported

as % loss of AChR)

Striational (striated muscle) antibodies: < 1:60

Test explanation and related physiology

These antibodies may cause blocks in neuromuscular

transmis-sion by interfering with the binding of acetylcholine (ACh) to ACh receptor (AChR) sites on the muscle membrane, thereby prevent-

ing muscle contraction This phenomenon characterizes nia gravis (MG) Antibodies to AChR occur in more than 85%

myasthe-of patients with acquired MG Lower levels are seen in patients with ocular MG only The presence of these antibodies is virtu-ally diagnostic of MG, but a negative test result does not exclude the disease The measured titers do not correspond well with the severity of MG in different patients In an individual patient, how-ever, antibody levels are particularly useful in monitoring response

to therapy As the patient improves, antibody titers decrease In adults with MG, there is at least a 20% occurrence of thymoma

or other neoplasm Neoplasms are an endogenous source of the antigens driving production of AChR autoantibodies

Several AChR antibodies can be associated with MG The

AChR-binding antibody can activate complement and lead to loss of AChR The AChR-modulating antibody causes receptor

endocytosis, resulting in loss of AChR expression, which lates most closely with clinical severity of disease It is the most sensitive test A positive modulating antibody test result may indicate subclinical MG, contraindicating the use of curare-like

corre-drugs during surgery The AChR-blocking antibody may impair

binding of ACh to the receptor, leading to poor muscle tion It is the least sensitive test (positive in only 61% of patients with MG)

contrac-Antistriated muscle antibody (striated muscle antibody, IgG)

titers greater than or equal to 1:80 are suggestive of myasthenia This antibody is detectable in 30% to 40% of anti-AChR–negative patients (particularly those with bulbar symptoms only) However, striated muscle antibody can be found in rheumatic fever, myocar-dial infarction, and a variety of postcardiotomy states

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6 acetylcholine receptor antibody panel

Drugs that may cause increased levels include muscle paralytic

medicines (succinylcholine) and snake venom

Immunosuppressive drugs may suppress the formation of these antibodies in patients with subclinical MG

Procedure and patient care

• See inside front cover for Routine Blood Testing

acid phosphatase 7

A acid phosphatase (Prostatic acid phosphatase [PAP],

Tartrate-resistant acid phosphatase [TRAP])

Type of test Blood

Normal findings

Adult/elderly: 0.13-0.63 units/L (Roy, Brower, Hayden; 37° C)

or 2.2-10.5 units/L (SI units)

Child: 8.6-12.6 units/mL (30° C)

Newborn: 10.4-16.4 units/mL (30° C)

Test explanation and related physiology

Elevated levels are seen in patients with prostatic cancer that has metastasized beyond the capsule to other parts of the body, especially bone The degree of elevation indicates the extent of disease This test is rarely performed for this indication; there are better tumor markers (p 194), including prostate-specific antigen (p 743)

Because acid phosphatase is also found at high concentrations

in seminal fluid, this test can be performed on vaginal secretions

to investigate alleged rape This is now the primary use of PAP testing Acid phosphatase is a lysosomal enzyme Therefore lyso-somal storage diseases (e.g., Gaucher disease and Niemann-Pick disease) are associated with elevated levels

Interfering factors

• Alkaline and acid phosphatases are very similar enzymes that differ in the pH at which they are identified Any condition associated with very high levels of alkaline phosphatase may falsely indicate high acid phosphatase levels

• Falsely high levels of acid phosphatase may occur in males after a digital examination or after instrumentation of the prostate (e.g., cystoscopy) because of prostatic stimulation

Drugs that may cause increased levels of acid phosphatase

include alglucerase, androgens (in females), and clofibrate

Drugs that may cause decreased levels include alcohol,

fluo-rides, heparin, oxalates, and phosphates

Procedure and patient care

• See inside front cover for Routine Blood Testing

• Fasting: no

• Blood tube commonly used: red

• Avoid hemolysis Red blood cells contain acid phosphatase

• Note on the laboratory slip if the patient has had a prostatic examination or instrumentation of the prostate within the past 24 hours

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8 acid phosphatase

• Do not leave the specimen at room temperature for 1 hour or

longer because the enzyme is heat and pH sensitive, and its activity will decrease

Metastasis to the bone

Sickle cell crisis

activated clotting time 9

A activated clotting time (ACT, Activated coagulation time)

Type of test Blood

Normal findings

70-120 sec

Therapeutic range for anticoagulation: 150-600 sec

(Normal ranges and anticoagulation ranges vary according to type of laboratory procedure and particular therapy.)

Possible critical values

Depend on use for the test and clinical situation

Test explanation and related physiology

The ACT is primarily used to measure the anticoagulant effect

of heparin or other direct thrombin inhibitors during cardiac angioplasty, hemodialysis, and cardiopulmonary bypass (CPB) surgery This test measures the time for whole blood to clot after

the addition of particulate activators It is similar to the activated partial thromboplastin time (APTT, p 681) in that it measures the ability of the intrinsic pathway to begin clot formation by

activating factor XII (see Figure  10, p 251) By checking the blood clotting status with ACT, the response to unfractionated heparin therapy can be monitored

Both the APTT and the ACT can be used to monitor heparin therapy for patients during CPB However, the ACT has several advantages over the APTT First, the ACT is more accurate than the APTT when high doses of heparin are used for anticoagu-lation This makes it especially useful during clinical situations requiring high-dose heparin, such as during CPB, when high-dose anticoagulation is necessary at levels 10 times those used for venous thrombosis The APTT is not measurable at these high doses The accepted goal for the ACT is 400 to 480 seconds during CPB

Second, the ACT is both less expensive and more easily formed, even at the bedside This allows for immediate accessibil-ity and decreased turnaround time The capability to perform the ACT at the point of care makes the ACT particularly useful for patients requiring angioplasty, hemodialysis, and CPB

per-A nomogram is often used as a guide to reach the desired level of anticoagulation This nomogram is used in determining the dose of protamine to neutralize the heparin upon completion

of these procedures The ACT is used in determining when it

is safe to remove the vascular access upon completion of these

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10 activated clotting time

procedures The benefits of the modified ACT test are that it

requires a smaller-volume blood specimen; it can be automated;

it can use standardized blood/reagent mixing; and it provides faster clotting time results than the conventional ACT The mod-ified ACT is now used more frequently

kid-• A clotted specimen can increase ACT measurements

Procedure and patient care

• See inside front cover for Routine Blood Testing

• Fasting: no

• Blood tube commonly used: verify with laboratory

• Less than 1 mL of blood is collected and placed in a machine

at the bedside When a clot forms, the ACT value is displayed

• If the patient is receiving a continuous heparin drip, the blood sample is obtained from the arm without the intravenous catheter

• The bleeding time will be prolonged because of tion therapy

anticoagula-• Assess the patient to detect possible bleeding Check for blood

in the urine and all other excretions, and assess the patient for bruises, petechiae, and low back pain

Abnormal findings

Increased levels Decreased levels

Heparin administration Thrombosis

Clotting factor deficiencies

Cirrhosis of the liver

Lupus inhibitor

Warfarin administration

notes

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adrenocorticotropic hormone 11

A

Type of test Blood

Normal findings

Adult/elderly:

Female: 19 years and older: 6-58 pg/mL

Male: 19 years and older: 7-69 pg/mL

Children:

Male and female: 10-18 years: 6-55 pg/mL

Male and female: 1 week-9 years: 5-46 pg/mL

Test explanation and related physiology

The ACTH tests the anterior pituitary gland function and provides the greatest insight into the causes of either Cushing syndrome (overproduction of cortisol) or Addison disease (underproduction of cortisol) An elaborate feedback mechanism for cortisol exists to coordinate the function of the hypothala-mus, pituitary gland, and adrenal glands ACTH is an impor-tant part of this mechanism Corticotropin-releasing hormone (CRH) is made in the hypothalamus This stimulates ACTH production in the anterior pituitary gland This, in turn, stimu-lates the adrenal cortex to produce cortisol The rising levels of cortisol act as negative feedback and curtail further production

of CRH and ACTH

In a patient with Cushing syndrome, an elevated ACTH level can be caused by a pituitary or a nonpituitary (ectopic) ACTH-producing tumor, usually in the lung, pancreas, thymus, or ovary ACTH levels over 200 pg/mL usually indicate ectopic ACTH production If the ACTH level is lower than normal in a patient with Cushing syndrome, an adrenal adenoma or carcinoma is probably the cause of the hyperfunction

In patients with Addison disease, an elevated ACTH level indicates primary adrenal gland failure, as in adrenal gland destruction caused by infarction, hemorrhage, or autoimmu-nity; surgical removal of the adrenal gland; congenital enzyme deficiency; or adrenal suppression after prolonged ingestion of exogenous steroids If the ACTH level is lower than normal in a patient with adrenal insufficiency, hypopituitarism is most prob-ably the cause of the hypofunction

One must be aware that there is a diurnal variation of ACTH levels that corresponds to variation of cortisol levels Levels in evening (8 pm to 10 pm) samples are usually one-half to two-thirds those of morning (4 am to 8 am) specimens This diurnal

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12 adrenocorticotropic hormone

variation is lost when disease (especially neoplasm) affects the pituitary or adrenal glands Likewise, stress can blunt or elimi-nate this normal diurnal variation

Interfering factors

• Stress (trauma, pyrogens, or hypoglycemia) and pregnancy can increase levels

• Recently administered radioisotope scans can affect levels

Drugs that may cause increased ACTH levels include

amino-glutethimide, amphetamines, estrogens, ethanol, insulin, metyrapone, spironolactone, and vasopressin

Corticosteroids may decrease ACTH levels.

Procedure and patient care

• See inside front cover for Routine Blood Testing

• Fasting: yes

• Blood tube commonly used: green

• Evaluate the patient for stress factors that could invalidate the test results

• Evaluate the patient for sleep pattern abnormalities With a normal sleep pattern, the ACTH level is the highest between

4 am and 8 am and the lowest around 9 pm

• Chill the blood tube to prevent enzymatic degradation of ACTH

• Place the specimen in ice water and send it to the chemistry laboratory immediately ACTH is a very unstable peptide in plasma and should be stored at −20° C to prevent artificially low values

Abnormal findings

Increased levels Decreased levels

Addison disease (primary

Cushing syndromeHypopituitarismAdrenal adenoma or carcinoma

Steroid administration

notes

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