Y khoa - Dược - Chapter 47: Processing and testing urine and stool samples

47Processing and Testing Urine and Stool Samples47.1 Discuss the role of the medical assistant in collecting, processing, and testing urine and stool samples.47.2 Carry out procedures for following guidelines when collecting urine specimens. Learning Outcomes47.3 Describe the process of urinalysis and its purpose. 47.4 Carry out the proper procedure for collecting and processing a stool sample for fecal occult blood testing.Learning OutcomesIntroductionProper collection of urine and stool specimens key to diagnosingMedical assistantLearn about urine and fecal specimensInstruct or assist patient in collection of a specimenConstituents of urine samplesChain of custody for drug screeningThe Role of the Medical AssistantCollect, process, and test urine samplesKnowledge necessaryAnatomy and physiology of kidneysHow urine is formedNormal components of urineRole of the Medical AssistantPotentially hazardous wasteStandard PrecautionsPPE as neededHandle and dispose of specimens properlyDispose of used supplies and equipment properlySanitize, disinfect, and/or sterilize reusable equipmentApply Your KnowledgeWhat does the medical assistant need to know related to collecting, processing, and testing urine specimens? ANSWER: The medical assistant needs to know the anatomy and physiology of the urinary system, how urine is formed, and normal components of urine.Very Good!Obtaining Urine Specimens General guidelinesFollow procedure for specified testUse appropriate specimen container Label specimen container correctlyExplain the procedure to patientWash your hands before and after; wear gloves Complete paperworkObtaining Urine Specimens (cont.)Instruct patientsTest-specific General Use correct containerDo not discard preservativeRefrigerate the collection containerKeep lid on the containerSpecimen TypesQuantitative analysisQualitative analysisVary in The method used to collect a specimen The time frame in which to collect a specimenFollow procedure exactlySpecimen Types (cont.)Random urine specimenMost commonObtained any time during the dayFirst morning specimenCollected after a night’s sleepContains greater concentration of substancesSpecimen Types (cont.)Clean-catch midstreamUsed for culturing urineExternal genitalia must be cleansedA small amount of urine is discarded prior to collecting specimenSpecimen Types (cont.)Timed urine specimenDiscard first specimenCollect all urine for specified timeRefrigerate 24-hour specimenTimed collectionInstruct as for a timed specimenCatheterizationProcedure by which the catheter is inserted into the bladderCatheterization (cont.)Reasons Relieve urinary retentionObtain a sterile urine specimenMeasure the amount of residual urine Obtain a specimen if patient cannot voidInstill chemotherapyEmpty bladder before and during proceduresCatheterization (cont.)Drainage cathetersIndwelling urethral catheter Retention catheter Ureteral catheterCystostomy tubeStraight catheter Splinting catheter – inserted after repair of ureter Catheterization (cont.)Not a routine procedure due to risk of infectionNot typically performed by medical assistantsCheck scope of practiceAssemble suppliesSpecial ConsiderationsMale and female patientsDifferences in collecting clean-catch midstream specimenQuestions during historyPregnant patientsFrequencyProne to urinary tract infectionUrine checked for glucose and proteinEstablishing Chain of CustodyDo not alter the procedureExplain procedure Consent form gives permission toCollect the specimenPrepare it for transport to laboratoryRelease the results to agency requesting testPreservation and StorageChanges can occur if urine is left at room temperature for more than 1 hourPreservationRefrigeration Prevents growth for 24 hoursReturn to room temperature before testingChemical preservatives Specimens onlyApply Your KnowledgeTrue or False: A random urine specimen can be collected any time. A clean-catch midstream urine specimen should be collected the first thing in the morning. Instruct the patient to discard the first specimen when  collecting a timed or 24-hour specimen. A chain of custody form gives you permission to release  the results to the agency requesting the test. Urine specimens should be refrigerated if they will not  be tested within four hours.ANSWER:TTTFFfirst morningoneUrinalysisEvaluation of urine to obtain information about body health and diseaseTypes of testingPhysicalChemicalMicroscopicUrinalysis (cont.)Values Negative or none, normal, or a range of concentrationWithin normal limits indicate health and normalityScreening – must have follow-up testingUrinalysis (cont.)Average adult daily urine output is 1250 mL/24 hoursIntake and output should be approximately the sameDysfunctions of other body systems can affect urinary functionPhysical Examination and Testing of Urine SpecimensCheck labelCheck for visible contaminationCheck time since collectionVisual examinationColor and turbidityVolume OdorSpecific gravityPhysical Examination and Testing of Urine Specimens (cont.)Color Pale yellow to dark amberConcentration Turbidity – clear or cloudyPhysical Examination and Testing of Urine Specimens (cont.)Volume 600 to 1800 mL/24 hoursOliguria Anuria OdorNot typically recordedDistinct, aromaticPhysical Examination and Testing of Urine Specimens (cont.)Urine Specific gravity1.002 to 1.028Fluctuates in response to fluid intakeMethods Refractometer Reagent stripsChemical Testing of Urine SpecimensCheck label Reagent strip testingColor changeFollow instructions carefullyChemical Testing of Urine SpecimensQuality assuranceKeep bottle tightly closedRemove strip just prior to useDo not touch padsCheck for discoloration and expiration dateDate new bottles and discard after 6 monthsChemical Testing of Urine Specimens (cont.)Ketone bodies Products of fat and protein metabolism Normally none in urineUrinary pHMeasure of acidity or alkalinityNormal 5.0 to 8.0Chemical Testing of Urine Specimens (cont.)BloodUse a strip that reacts with hemoglobin Hematuria Hemoglobinuria Myoglobinuria Chemical Testing of Urine Specimens (cont.)BilirubinBreakdown of hemoglobinBilirubinuria ~ early sign of liver diseaseUrobilinogen Elevated – increased RBC destructionLacking – bile duct obstructionChemical Testing of Urine Specimens (cont.)GlucoseNormally in small amountsGlycosuria – diabetes ProteinNormally excreted in small amountsProteinuria – excess protein in the urineChemical Testing of Urine Specimens (cont.)Nitrite – suggests bacterial infectionLeukocytes – urinary tract or renal infectionPhenylketonesPhenylketonuria (PKU) Blood testing is more routine for newbornsChemical Testing of Urine Specimens (cont.)Pregnancy testsDetect human chorionic gonadotropin (HCG)Quick, easy to perform and interpretEnzyme immunoassay (EIA) testChemical Testing of Urine Specimens (cont.)Presence of STDsScreening for chlamydiaNucleic acid amplification tests (NAATs)Detect nucleic acid in urineChlamydia and gonorrhea Advantages vs. disadvantagesMicroscopic Examination of Urine SpecimensView elements only visible with microscopeCentrifuge Spins urine ~ heavier substances settle to the bottom of the tubesSediment examinedMicroscopic Examination of Urine Specimens (cont.)Cells Epithelial cellsRenal Transitional Squamous White blood cellsRed blood cellsMicroscopic Examination of Urine Specimens (cont.)Casts Cylindrical elementsProtein Classification Hyaline GranularRBC castsWBC castsEpithelial cell castsWaxyMicroscopic Examination of Urine Specimens (cont.)Crystals Naturally produced solids of definite formCommon in urineDetermine pH before identifying Microscopic Examination of Urine Specimens (cont.)Yeast cellsMay be confused with RBCsAssociated with genitourinary tract infection, diabetesBacteria A few are normalInfection if odor and WBCs are presentParasites – may indicate infectionApply Your KnowledgeWhat is the specific gravity shown on this refractometer screen?ANSWER: The specific gravity shown here is 1.030.Apply Your KnowledgeMatching: pale yellow to dark amber cloudiness absence of urine measure of concentration of urine acidity or alkalinity of urine genetically inherited disorder may indicate tubular damage cylinder-shaped sediment of proteins naturally produced solids in cool urineCastsSpecific gravityNormal colorRenal epithelial cellsCrystals Turbidity PKUpHAnuria ANSWER:Super!ABCDEFGHICollecting and Processing Stool SpecimensScreening for colorectal cancerFecal occult blood testTests for hidden bloodFoods and medication may cause false-positivesPatient instruction important Collecting and Processing Stool Specimens (cont.)Suspected Bacterial InfectionShigella or Salmonella Loose, bloody or mucus-tinged stoolsCulture media Promote growth of intestinal pathogenSuppress growth of other microorganismsCollecting and Processing Stool Specimens (cont.)Suspected Protozoal or Parasitic Infection O & P specimenThree separate sets of fresh and preserved specimensSpecial kits availableApply Your KnowledgeBesides how to collect the stool sample for FOBT testing, what else do you need to tell the patient? ANSWER: The patient need to know to follow all pretest dietary and medication instructions.In Summary47.1 Your role as a medical assistant includes collecting, processing, and testing urine samples, and processing and testing stool samples. You will also be responsible for teaching patients proper collection methods for urine and stool samples. In Summary (cont.)47.2 The general guidelines for collecting a urine specimen include: following the procedure specified for the urine test that will be performed; using the type of specimen container indicated by the laboratory; properly labeling the specimen container; explaining the procedure to the patient when assisting in the collection process; washing your hands before and after the procedure and wearing gloves during the procedure; and complete all necessary paperwork.In Summary (cont.)47.3 Urinalysis is the evaluation of urine by various types of testing methods to obtain information about body health and disease.In Summary (cont.)47.4 The general guidelines for collecting a stool specimen include: instructing the patient about the need to follow all collection procedures including when to collect, how to collect, and how to return the specimen to the office; following the testing procedure for fecal occult blood testing, using Standard Precautions when performing the test; and documenting the test and results in the patient’s chart.End of Chapter 47A human being: an ingenious assembly of portable plumbing. ~ Christopher Morley, 1890-1957