QUALITY ASSURANCEUrinalysis

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Introduction

• Urinalysis seems to be an ideal test• The sample is easy to collect; • the test procedures are simple and uncomplicated

• Unfortunately the development of a quality assurance program for urinalysis has lagged behind other areas of the laboratory

• Because of its simplicity and low regard in the laboratory it is not unusual to find that the least experienced and trained technologist and technicians are assigned to this workstation

• These individuals more often than not do not understand the importance of adhering to test procedures and fail to recognize or correctly count the formed elements in the urine sediment

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Introduction• The macroscopic and microscopic examination of urine

can reveal important insights to a patient's physical condition and state of health

• Until recently little effort has been spent on the standardization of this widely practiced procedure

• The quality of the laboratory result can be improved and maintained with a small amount of effort placed in assuring: • sample integrity • standardization of procedures• and correct interpretation and reporting of the urine sample

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Major Errors In Urine Testing

1. Failure to test a fresh specimen

2. Inadequate communication between the laboratory and the patient or nursing staff for collecting a urine specimen properly

3. Use of unclean collection containers, tubes, and slides

4. Inadequate care of specimen

5. Improper recording of information and test results

6. Poor or inconsistent technique in using the reagent dipstick

7. Inadequate understanding of interfering substances

8. Failure to mix urine specimen (blood, bacteria, casts) before pouring---a-portion for the microscopic analysis

9. Incomplete training of personnel to perform properly the technical aspects of the urinalysis or to identify elements in the sediment

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Specimen Collection

• Most routine urinalysis is performed on a freshly collected random urine

• Regardless of when the sample is to be obtained, clear and concise written instructions are necessary for both patients and nursing personnel

• The validity of a test result is no better than the quality of the specimen

• Once the urine specimen has been collected it should be processed immediately to prevent deterioration

• If samples can not be processed within 1-2 h of collection, they should be refrigerated or preserved

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Specimen Collection

Types of Urine Specimens

• Random specimen: • A urine specimen collected at any time by either clean catch,

catheterization, or suprapubic aspiration• Random specimens are collected most often for routine urinalysis

• First morning specimen: • A urine specimen collected upon rising from sleep in the morning• First morning specimens are also used for routine urinalysis

• Postprandial specimen: • A urine specimen collected at a specific interval after eating• This type of sample is used to evaluate a diabetic condition, either as part

of a glucose tolerance test, or for the control of a diabetic state

• Specially timed specimen (2-hour and 24-hour specimen):• Involve the collection of all urine in the specified time period• used in various renal function tests such as creatinine clearance

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• It is important to recognize which preservative is necessary for which test

• Type of preservative should me marked on the container to ensure safety

• Some of the more common methods of preservation include:• Freezing

• Destroys cells and some components

• Refrigeration• Preferable method, sample should come to RT before analysis

• Commercial preparation tablets• For routine urinalysis in absence of refrigeration

• Formalin, Toluene, Chloroform, Phenol & other chemicals• used mostly for 24-hour specimens

Specimen Collection

Preservation of Urine Specimens

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The Decomposition Of Urine • Urine undergoes these changes after collection if proper

steps are not taken to preserve it

• Ascorbic acid: Decreases and may disappear

• Ammonia: Increases • Glucose: Decreases and disappears • Bacteria: increase • Nitrite: Appears • Casts: Disappear • Red blood cells: Hemolyze • Occult Blood: Reactivity appears or

increases

• pH: May increase • Color: Darkens • Odor: Becomes smelly • Turbidity: Develops • Protein: May appear or

disappear • Bilirubin: Decreases and

disappears • Urobilinogen: Decreases and

disappears • Ketone bodies: Decrease and

disappear

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Procedure Manual• Should pay special attention to the collection procedure• Should specify which preservatives are appropriate for which

tests and should detail the proper labeling of these sample containers

• Definition of the various formed elements in the sediment should be clear and methods of reporting should be well defined

• Arbitrary terms such as small, moderate, and large should be avoided and semiquantitative terms such as trace, 1+ , and 2+ should be defined to help reduce reporting inconsistencies between individuals

• Instructions for the preparation of control samples should be included in the urine procedure

• The control tolerance limits should be clearly displayed and specific actions to be taken when limits are exceeded

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Standardization Of The Urinalysis Procedure

• The routine urinalysis is divided into two parts:• the chemical urinalysis • and the microscopic urinalysis

• Until recently the chemical urinalysis was performed manually with: • Reagent strips

• The determination of the final color of the strip pad is a subjective one and two persons may interpret the same test in different ways

• The timing between immersion and reading the strip is another source of variation between one individual and another

• The longer the reaction is allowed to proceed before reading, the darker the color development• Consistent timing is important for precision and accuracy

• Or reagent tablets• The reagent tablets are also colorimetric reactions that require

timing and interpretation by technologists

Positive

Negative

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• The manual performance of the chemical portion of the urinalysis is subject to imprecision and inaccuracy due to shortcuts and inconsistent performance

• The introduction of automated readers has improved the precision and accuracy of the chemical portion

• Light is directed to the pad and the intensity of the reflected light is measured

Standardization Of The Urinalysis Procedure

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• The introduction of standardized systems for performing the microscopic examination reduces another variable in the urine procedure

• These systems standardize: • the volume of urine used to collect the sediment• the force of centrifugation• the volume of urine in which the sediment is resuspended• and the volume of sediment examined for cells and casts

Standardization Of The Urinalysis Procedure

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Quality Control • Commercially prepared controls for the chemical portion

of the routine urinalysis are available for the reagent strips and tablets

• Lyophilized urine samples or reagent sticks with impregnated chemicals that dissolve in measured amount of water

• Positive and negative controls are available to check the sensitivity of the reagent system

• Both positive and negative controls should be run daily and when opening a new bottle of reagent sticks or tablets

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Reagent And Instrumentation Quality Assurance • Reagent sticks and tablets should be stored under

conditions specified by the manufacturer to prevent the absorption of moisture and prevent exposure to light that may degrade some of the chemicals in the reagent pads

• Written maintenance procedures and schedules for all instrumentation in the urinalysis laboratory should be kept current and reviewed for compliance by the laboratory director or his designee

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