Home > GENERAL > IMPORTANCE OF PRE-ANALYTICAL SPECIMEN COLLECTION

IMPORTANCE OF PRE-ANALYTICAL SPECIMEN COLLECTION

Introduction

Many people did not really understand the scope of medical laboratory function. Many patients think that taking specimen such as blood is just for routine test such as blood glucose, cholesterol or blood pressure. It is not the really job of this profession, actually laboratory test have wide scope and we do many tests that provide clinical diagnostics data for doctors to give a proper treatment for the patients. Laboratory test are important because it can determine health condition of people.

Laboratory test have important roles in determine what kind of disease patients have. So for that, we must follow some rules for get a correct result for correct patients in purpose helping the diagnosis part.

Factors That Affect Phase of Pre-Analytical

There are few stages that effects to get good quality of results and correct results:

  1. Pre-analytical – Before taking patient’s specimen.
  2. Analytical – During analysis or do the test.
  3. Post-analytical – Reporting the test results.

Laboratory error occurring during the pre-analytical (from the time the test is ordered by the physician until the sample is ready for analysis) can account for up to 80% of the errors encountered during the total diagnostic process. Error from pre-analytical phase can cause the patients get wrong results. Errors at any stage of the collection, testing and reporting process can potentially lead to a serious patient misdiagnosis.

STAGES SPECIMEN COLLECTION PROCESS
Before
  • Identification of patient and registration of patients in hospital.
  • Type of test.
  • Patient’s preparation.
  • Preparation of labeled tubes with patient’s identification and requisition forms for some test.
During
  • Right technique.
  • Vein selection for blood sample.
  • Using of correct collection tubes and container.
  • Labeling of collection tubes with patients identifications.
  • Correct requisition forms.
After
  • Specimen transport.
  • Specimen handling and processing.
  • Storage of specimen.

Patients Registration

  • Anyone that come to government clinics or hospital must register in unit of registration.
  • In this process, patient will give complete information to hospital personnel.

– Full name

– Identification number

– Date of birth

– Home address

– Phone number

– Beneficiary details

– Related information

  • When this tasks is completed by patient, their given the medical record number (MRN) by hospital registrar. This MRN is different from one patient to other patients. This MRN also identification for a patient along with their name and identity card.
  • Information of patient such as name, my card identity number MRN are important and must write in laboratory form and patient specimen container.
  • Generally every patient must have 2 type of identification for written in their laboratory form and specimen container. It makes the process of analysis of samples are more easy and convenient for laboratory technician and doctors to interpretiate the right result of analysis to right patients.
  • Even one patients get medical services more than one hospitals, they will get MRN number for each hospital, this shows that MRN number are different and unique for purpose of identification patient data in getting right treatment and did not happened cross-data of patient between another hospitals.

Type of Specimen and Test

Type of specimen that tested in laboratory is blood, urine, stool, sputum, saliva, pus from open wound and others body fluids. Every test that ordered by doctors must done with suitable specimen depend of requirement of test.

(a) Blood specimens  (b) Urine specimens

Picture 1 (a), (b): Type of specimen

Preparation of Patient

Before taking patient’s specimen, preparation of patient are important because some test need patient to be fasting more than 8 hours such as glucose or cholesterol test.

Some patient variables that affect blood specimens.

  • Allergies to alcohol or iodine used to clean venipuncture sites.
  • Obesity.
  • Diet- eats 30 minutes before taking blood.
  • Moderate to strenuous exercise can change the laboratory test results.

Collection Tubes, Container and Requisition Forms

  • Using of right of tube collection or container of specimen are important because it will make results of test is accurate.
  • Doctors have to follow as pre analytical rules is write summary of patient’s history and pathological problems in laboratory forms.
  • The purpose of provide info of patients is that maybe can useful for analysis of sample that done by laboratory technician.

Picture 2: The example of requisition form.

Blood Specimens Collection

Good technique of blood taking by doctors and nurse must be practices to all patients. Right technique of blood taking will give accurate results and others benefits :

  • Minimizes trauma to patient.
  • Minimizes potential for phlebotomist injury.
  • Reduces recollections because of blood clotting or lysed.

A successfully taking of blood sample is determined by few steps, that is:

  • Vein selection essential for successful venipuncture.
  • Use of appropriate needle size.
  • Cleansing of the blood collection site with alcohol swab.
  • Sufficient of blood sample for requirement of test ordered by doctors.
  • Use of appropriate of tubes and container of specimen.
  • Proper tube mixing.
  • Tubes and container labeled with 2 unique identification of patients like name, MRN and national registration number.

Transportation of Specimen

As universal precaution all specimens should be regarded as potentially hazardous or infectious.  Universal blood and body fluid precautions should be observed. There are two main categories of transportation methods, that is medical courier and pneumatic tube.

Transportation of inpatient and outpatient samples

– Specimen is sent by medical assistant in hospital and this kind of transportation use human energy as transport.

– The negative site of this kind of transportation is limited time and patients have to wait long time get the results.

Pneumatic tube

– Is a system in which cylindrical containers are propelled through a network of tubes by compressed air or by partial vacuum.

– The benefit of this system are efficiently transport carriers at high speeds with proven reliability and long-distance transport overhead, underground, between buildings

– The disadvantage during the delivery are the system can broke the specimens that have highly sensitivity and limit total of specimen that can be send in one time.

Picture 3: Pneumatic tube

Handling of Specimen for Clinical Diagnostics

Identification

  • Identification of patient’s info must be correct in specimen label and requisition forms.
  • Sample are labeled by barcode that have demographic of patients registered by hospital administration.

Picture 4: Example of Barcode

Preservative

  • Preservative of sample are must correct with type of specimens.
  • In laboratory, the specimen will prepared for clinical diagnostics with some methods like blood specimen are centrifuge for separate the plasma or serum, add additives, frozen and some samples are been frosted by ice also serum dilute with water.
(a) Centrifuge of Specimen (b) Separate serum from blood specimen

Picture 5 (a), (b): Specimen for clinical diagnostic

Isolation & storage

  • The specimen must be centrifuge to separate of serum or plasma within 2 hours after collection of the specimen. If the analysis or test is not done in same day, the serum must be separated in closed tube in refrigerator at temperature (3 Celsius – 5 Celsius) until the test will do.

Transmission

  • Container or tubes of specimens must in good condition that can preserve the specimen condition from broken, contamination, high temperature or low temperature that cause the specimen in not good condition for analysis.
  • All specimens must put in Biohazard Plastics before taken to laboratory for avoid any chances of spread of infection. Putting the samples in Biohazard Plastics will remind all hospital personnel to handle will care.

Picture 6: Biohazard plastic with blood specimen

Potential of Error in Sampling analysis

PROCESS POTENTIAL ERROR
Test ordered
  • Test ordered is not relating or suitable with clinical condition of patients.
  • Bad hand writing in requisition form.
  • Wrong identification of patient’s information.
  • Do not write the purpose of doing this test.
  • Test ordered in not suitable time or late ordered, this cause the test cannot be done.
Received samples
  • Wrong container or tube for the specimens.
  • Wrong patient’s identification.
  • Insufficient of samples.
  • Condition of samples not suitable for analytical example like blood lyses and diluted.
  • Wrong timing of blood collection.
  • Improper of mechanism transportation.
  • Sample collection mishap- clotting.
Analytical process
  • Wrong instrument of calibration.
  • Specimen contaminated with other samples.
  • Wrong amounts of samples.
  • Presence of endogenous/ exogenous interference the test.
  • Instrument malfunction.
Reporting of results
  • Incorrect patient’s identification.
  • Report don’t have related graph or histogram
  • Delays validation of laboratory report.
  • Inappropriate report that difficult to interpretation.
Interpretation of test
  • Specification of purpose test is not understood.
  • Limit of accuracy of test is unknown.
  • Sensitivity of measure tools is unknown.

 

Last Reviewed : 3 January 2017
Translator : Norhaniza binti Musa
Accreditor : Dr. Shahannim binti Izham