Phlebotomy Notes

Online Ancillaries: The course has online ancillaries like videos on: collecting a blood culture specimen, collecting blood for hemoglobin determination, fingerstick glucose, flashcards, and an audio glossary.
Internet Resources: It also provides internet resources such as: Advance magazine for medical laboratory personnel, Typenex Medical LLC, Center for Phlebotomy Education, Genzyme Diagnostics (OSOM training), and Hemochron Signature Elite Videos.
Other Resources: There is a student workbook for Phlebotomy Essentials and Phlebotomy Exam Review available for purchase.

Computers and Specimen Handling and Processing

NAACLS Entry Level Competencies:
- Identifying and labeling biohazardous specimens properly
- Listing general criteria for specimen suitability for analysis, also listing reasons for specimen rejection or recollection.
- Demonstrating understanding of requisitioning, specimen transport, and specimen processing.
- Explaining methods for transporting and processing specimens for routine and special testing.
- Explaining methods for processing and transporting specimens for testing at reference laboratories.
- Identifying and reporting potential preanalytical errors that may occur during specimen collection, labeling, transporting, and processing.
Key Terms: Focus on understanding and gaining familiarity with several key terms related to the subject matter.

Objectives

Demonstrate knowledge of computer systems, terminology, and specimen flow in a laboratory information system LIS.
Explain specimen handling procedures, identify preexamination/preanalytical errors in collection, labeling, transport, and processing.
Describe specimen processing steps, time constraints, exceptions for delivery, and specimen rejection criteria.
Identify the OSHA-required protective equipment for specimen processing.

Overview

Computerized networking connects patient care aspects, tracking specimens from collection to result reporting.
The chapter covers computer components, skills, and terminology and specimen handling and processing, helps avoid errors, and ensures accurate results, following CLSI standards.

Computers

Computers provide improved efficiency and productivity in daily lives and healthcare.

Computerization in Healthcare

Computers manage data, identify and monitor patients, automate analyzers, and aid in diagnosis.
Computer literacy is a required skill for healthcare workers (HCWs):
- Know basic computer terminology (Table 12-1).
- Understand the computer and its functions.
- Perform basic operations using computers.
- Demonstrate willingness to adapt to changes computers bring to our lives.

Common Computer Terminology (TABLE 12-1)

Accession number: A unique number generated when a test request is entered into the computer. It serves as a singular identifier for that specific test request and associated sample.
CPU: Central Processing Unit; the primary component of a computer that executes instructions.
Cursor: The flashing indicator on a monitor screen that shows the location where the next character will be entered.
Data: Information gathered for analysis or computation. This can include patient demographics, test results, quality control values, etc.
Hardware: The physical components of a computer system, including the CPU, monitor, keyboard, and printer.
Icon: A small graphic representation of a computer application, file, or function.
ID code: A unique identifier (alphanumeric) used to track a person or specimen.
Input: Data or commands that are entered into the computer. Examples include patient information from a keyboard or barcode data from a scanner.
LIS: Laboratory Information System; a software system designed to manage and track all the data and workflow of a clinical laboratory.
Logging on: The act of gaining access to a computer system by entering a username and password.
Middleware: Software that connects two otherwise separate applications, allowing them to exchange data. In healthcare, it often connects POCT devices with the HIS.
Mnemonic: A memory-aiding code or abbreviation, e.g., using "CBC" to remember "Complete Blood Count."
Online: Descriptive of a computer system when it is active and ready for use.
Output: The result of data processing, which could be displayed on a monitor, printed on paper, or sent to another device.
Password: A secret code used to verify the identity of a user and gain access to a computer system.
Peripherals: Devices that are connected to a computer and used for input/output, such as printers, scanners, and modems.
RAM: Random access memory; a type of computer memory that allows data to be stored and retrieved quickly. It is volatile, meaning that data is lost when the computer is turned off.
ROM: Read-only memory; non-volatile memory containing instructions that the computer uses during startup.
Software: The set of instructions that tells computer hardware what to do, enabling it to perform tasks.
Storage: A place for keeping computer data, either inside the computer (primary storage) or on external devices like USB drives (secondary storage).
Verify: Checking or confirming correctness of input. In an LIS, this might involve reviewing patient information post-entry for accuracy.

Computer Components

To make a computer run, users employ three basic components: a means to input information, a way to process information, and a method to output information.
Input Component: The most common way to input (enter) data into a computer is to use a keyboard. Other ways include a light pen; touchscreen, using a finger or stylus (pen-like device); scanner programmed to read figures, letters, and barcodes; mouse; or a touch-sensitive pad. There is also direct transfer or downloading from another device such as a compact disk (CD), digital video disk (DVD), or other external memory device.
Description: Wireless keyboard and mouse.
Processing Component: After information has been input, it is processed through the central processing unit (CPU), which is the thinking part of the computer that does comparisons and calculations and makes decisions. When you enter new data it is stored in memory until the processor can execute the command. Memory may be of two types: random access memory (RAM) and read-only memory (ROM).
RAM (main memory) serves as temporary storage for data that will be lost when the computer is shut off. If the information needs to be kept for a later date, the operator must transfer it to secondary storage in the form of a hard drive, universal serial bus (USB) drive, or the cloud.
ROM storage which is installed by the manufacturer and permanently stored inside the computer, instructs the computer to carry out operations requested by the user.
Description: Wireless keyboard and mouse.
Output Component: Output describes the processed information or data generated by the computer to be received by the user or someone in another location. Output devices include the computer screen, printers, and other devices such as smartphones, and tablets.

Computer System Elements

You should recognize the different computer elements.
There are three basic elements that make up computer systems; hardware, software, and storage.

Hardware

Hardware is equipment used to process data; it includes the CPU and peripherals (any computer device that is external to the CPU) used for the input or output of information.
Examples of hardware peripherals are keyboards, computer monitors, or screens, barcode readers, scanners, handhelds, facsimile (fax) machines, printers, modems, and routers that are used to transfer data to and from other computers.
A computer screen and keyboard combination is called a "terminal". These are necessary peripherals for most computers and are found throughout the laboratory at workstations or directly connected to an analyzer.

Software

Software is the programming (coded instructions) designed to operate the computer hardware in the processing of data. Two basic types exist: systems software and applications software.
Systems software is the built-in, preinstalled basics of the computer. It controls the normal operation of the computer and is the operating system that communicates between the hardware and the applications.
Applications software refers to programs prepared by software companies or in-house programmers to perform specific tasks required by users.
Software packages that perform more than one application, such as word processing, spreadsheet, and database, are called integrated software.
A special type of applications software called middleware is especially important to the use of POCT instruments.
Middleware is sometimes called "plumbing" because it connects two sides of an application and passes data between them.
Middleware programs accept data downloaded from point-of-care test (POCT) instruments and serve as an interface between the analyzers and the hospital computer system, referred to as the hospital information system (HIS).
Through this software, the test results can be entered into a patient’s electronic chart, and a charge can be submitted to the hospital financial software system that will capture the billing.
Middleware in a healthcare setting can also be used as a conduit for data storage, report generation, operator competency tracking, instrument and interface monitoring, and even tracking of errors for quality control/improvement programs.

Storage

Because RAM storage in the CPU is temporary, permanent secondary storage outside the CPU is necessary for preserving information. Secondary storage adds to CPU memory capacity by allowing information transfer back to the CPU when needed.
Examples of permanent secondary storage devices for documents and programs are external back-up drives, USB drives, DVDs, and storage in the cloud, which is off-site storage maintained by a third party.
The benefit of cloud storage is that it gives the user unlimited disk space and the ability to connect from multiple devices in any location that has internet capabilities.

Computer Networks

A computer network is a group of computers that are all linked so that they can share resources. In a computer network, individual computer stations, tablets, and even smartphones are called “nodes”
The network interconnection allows all the computers to have access to each other’s information or to a large database of information on a mainframe at a remote site.
Networking can take the form of simple interoffice connections or complex systems between several organizations in different cities or across continents.
A good example of a large and complex system is the internet, in which computers all over the world can access multiple sites and unlimited information.
Handhelds, laptops, mobile phones, tablets, datacards, and routers (devices that forward data between computer networks) allow any user to connect to the internet from wherever there is a wireless network supporting that device’s technology.
This immediate access speeds up processing, increases productivity, and reduces costs, and is one of the reasons accountable care organizations (ACOs) and large managed care systems can grow and flourish.
Key Point: Computer networking makes information sharing so easy that patient confidentiality can be violated.
Congress took steps to eliminate confidentiality violation by enacting the Health Information Portability and Accountability Act (HIPAA), which is designed to protect the privacy and security of patient information by standardizing the electronic transfer of data and providing guidelines for sharing protected health information (PHI). This federal law affects everyone involved in healthcare: patients, physicians, and other healthcare personnel, healthcare organizations, vendors, and insurance companies.

Computer Security

Like most other computer networks, healthcare computer networks have a firewall that monitors and controls network traffic to prevent unauthorized access to or from the network.
Network managers continually monitor for data leaks or a breach (break in a firewall) in the database.
There are reports that private information in healthcare facility patient records is quickly becoming a favorite target of hackers.
According to the MIT Technology Review, there are two reasons for the sharp increase in data breaches in healthcare facilities.
All healthcare information systems use complete data encryption (conversion to a form that only authorized individuals can read) in addition to satisfying HIPAA and other regulatory requirements.

Laboratory Informatics

The specialized application of information technology, such as the development, maintenance, and use of computers, computer systems and networks, to store, retrieve, and send information to optimize laboratory operations is called laboratory informatics.

Laboratory Information System

A laboratory information system (LIS) is a major part of laboratory informatics. It is a customized computer software package designed to record, process, manage, and store data from a variety of workflow processes in the laboratory.
Similar to, and sometimes referred to as a laboratory information management system (LIMS), this sophisticated software serves a variety of purposes, including operations and data management; security and quality control; interactive interface with instrumentation; information sharing with the HIS and electronic health records (EHRs); and interfacing with external information systems, such as national and regional reference laboratories.
The advantages of using an LIS are faster turnaround times (TATs); reduced clerical and billing errors; flexible delivery options for reports, workload, and statistical reports; and increased efficiency with cost savings in all areas of the laboratory.
There are multiple vendors and types of LISs currently on the market.
Each type of LIS allows users to define their own parameters for terms and conditions that make the system unique to that facility.
Several programs within the system allow phlebotomists and specimen processing personnel to do specific tasks, seemingly at the same time, such as admit patients, request test orders, print labels, evaluate and enter results, inquire about results, and generate reports.
Each LIS user must have a username and password.

Usernames

To login to the LIS you will be given a username (a unique combination of characters sometimes called an ID code or user ID) that identifies you as a system user.
The security associated with your username determines what system functions you can access.
Because a username is logged with every transaction on the system, the system manager can identify the person performing each transaction, and manage workload.
Usernames are not always confidential because it is not always possible for phlebotomists to verify their own collections.

Because a username is logged with every transaction on the system, the system manager can identify the person performing each transaction, and manage workload.

Law and Ethics: You discover that an acquaintance is a patient in your institution. You have access to his personal information via the LIS. Even though you do not have a valid reason to access his information, it may be tempting to look up his diagnosis, lab results, or other personal information. This is not only unethical but also a HIPAA violation that could get you fired and in legal trouble.
Penalties for HIPAA violations include disciplinary action, fines, and possible jail time. You could also face a civil breach of confidentiality lawsuit.

Passwords

In addition to a username, you must also have a password (secret phrase or code) to log onto the LIS. Your username tells the computer who you are, and your password provides proof that you are that person.
Passwords must be kept strictly confidential. This means you should not use the system if another user is logged on nor share your username and password with someone else.
A password should be easy to remember, so it does not have to be written down, but strong so it is hard to guess.
A strong password has multiple characters (usually eight or more), including a mix of letters (upper and lower case) and numbers, and one or more special characters like asterisk (*) or ampersand (&) to make it more difficult for hackers to guess. It should also be changed regularly.

Icons and Mnemonic Codes

Some lab systems use icons or images to request the appropriate program or function necessary to enter data. Others may use a menu of mnemonic (memory-aiding) codes or an abbreviation for selecting a function.
A mnemonic code to identify the type and volume of tube required is printed when a label is generated.

For example, if the phlebotomist knows that a complete blood count (CBC) is ordered and the code on the label reads “5 mL LAV,” he or she knows what tube type to choose and the amount of blood to draw (in this case, a 5-mL lavender-top). This demonstrates one of the benefits of computerized label generation; the label aids the phlebotomist in acquiring the proper specimen in a timely fashion.

The generic steps used by the LIS for processing a typical specimen, from arrival in the lab through reporting of results, are shown in the flowchart in Figure 12-5.

Barcodes

A barcode is a visual depiction of data in the form of a code that can be read by an electronic device. Barcodes can exist as linear one-dimensional (1D) codes, or as two-dimensional (2D or matrix) barcodes.
1D barcodes use a parallel array of alternately spaced black bars and white spaces to represent the code. Figure 12-6 shows a linear barcode label produced by the LIS and printed on a barcode label printer.
2D barcodes use rectangles, dots, and other geometric patterns in 2Ds (Fig. 12-7). 2D barcodes can carry more information than the older linear codes. In both cases, the code represents numbers or letters.
A quick response (QR) code is the name for a type of 2D barcode that was initially designed for the automotive industry. The code consists of black squares arranged in a square grid on a white background. Data is contained in patterns present in horizontal and vertical components of the image.
Most laboratory and POCT analyzers use barcode technology for specimen identification.
Barcodes containing the patient’s information are printed on ID bands, test requisitions, and specimen labels.
Barcode use saves time (which shortens TAT), and reduces errors associated with manually recording patient information on specimen labels or entering information into the LIS or individual analyzers.
Wireless handheld devices are used at the bedside to read the barcodes on patient ID bands and generate the labels used for specimen collection.
For blood specimen collection, the typical handheld device identifies the patient, displays the collection tubes and their order of draw, scans the tubes and prints the correct labels with the time of collection, and identifies the person who is collecting the specimens.

Radio Frequency ID

Another form of identification using computer technology is radio frequency identification (RFID).
RFID is a unique identifier that can be scanned to retrieve identifying information and wirelessly track a product or person. This ID system is composed of a reader and a tag or label that serves the same purpose as a barcode or the magnetic strip on a credit card.
The RFID tag looks very much like a barcode label but is actually a silicon chip.
One of the advantages of this system is that it does not need to be near the object being scanned because it communicates data by radio waves.
Another advantage is that the RFID scanner can track more than one tag at a time and beyond the line of sight of the reader.
In healthcare, it is used to monitor patients and identify and track specimens, equipment, and records.
At present, barcodes are more accepted and less expensive, but with the standardization of the RFID industry and the cost of tags decreasing, the technology is becoming more commonplace in healthcare.

General Laboratory Computer Skills

General skills that the phlebotomist must learn, regardless of which LIS is used, involve the following:
- Logging on: LIS access via username and password, with unique user access to certain menus/programs.
- Cursor movement: Reset at correct point for data input after pressing enter key.
- Using icons: Initiating access via mouse click.
- Entering data: Pressing Enter key to process; easy deletion before pressing Enter, but corrections may be hard.
- Correcting errors: Program-dependent deletion procedures; order verification allows information review before acceptance.
- Verifying data: Complete order displayed on monitor for user to modify, delete, or accept.
- Making order inquiries: Retrieving test orders associated with a patient.
- Canceling orders: Requesting the computer to delete or cancel an incorrect order.

Computerized Analyzers

Computers are accurate processors of information at incredible speeds at that computerized laboratory analyzers are considered more efficient and cost-effective than relying on manual methods.
Most laboratory analyzers have sophisticated computer systems designed to manage patient data and interface (connect for the purpose of interaction) with the LIS.
In the laboratory, multiple computers can connect to each other and share data. Two types of interfaces are used in the LIS.
One is a unidirectional interface, which means data only go one way, from the analyzer to the LIS computer. The second interface is bidirectional, meaning data can upload (transfer from analyzer to LIS) or download (transfer from LIS to analyzer) between two systems.
Major manufacturers of laboratory analyzers have the capability to connect their computer via the healthcare facility’s internet with an analyzer in their customer’s laboratory to monitor the instrument’s status and to troubleshoot.

Interfacing and Integrating

Today’s healthcare facility is quickly moving toward being totally integrated (connected) through networking of computers with the appropriate middleware.
Some of the healthcare computer systems that typically interface with each other include EHR, HIS, LIS, radiology information system (RIS), dietary services, and the emergency department.
An example of successful integration in the hospital setting is POCT.
Because sophisticated testing is possible at the patient’s bedside, the results need to be captured for appropriate treatment, accurate patient records, and documented in the EHR for access by care providers.
While most point-of-care (POC) analyzers are interface capable, the decision to interface is based on the number of tests performed and the impact of the test on the patient. For example, a troponin result may need to be received by the physician immediately while the result of a creatinine is not as critical.

Connectivity Industry Consortium

To be used effectively, POC instruments must integrate with many different institutions’ information systems. This requirement has led to formation of the Connectivity Industry Consortium (CIC), which was established to ensure that any POC analyzer could talk to any LIS.
A guideline for standardization was developed by POC analyzer manufacturers, LIS vendors, and healthcare providers that resulted in the CLSI Point-of-Care Connectivity, Approved Standard, Second Edition.
Current trends in healthcare indicate that clinical laboratory operations will continue to decentralize and that POC testing will increase.
The need for complete networking becomes even more apparent as remote laboratory testing facilities increase in numbers.
Today, large reference laboratories totally separate from the healthcare facilities can download results from automated instruments into patient charts and centralized databases.
Computerization and instrumentation such as the system shown in Figure 12-10, make that possible. After the specimens have been collected and recommended clotting times have been met, if applicable, specimens are placed in a system module (Fig. 12-11) to start testing.
*Through computer connections with the rest of the specimen processing modules and the specified analyzer in the laboratory, the test results arrive in a patient’s EHR in the hospital or physician’s office without any manual implementation required.

Specimen Handling and Processing

As part of the computerization network that connects many aspects of patient care, the LIS tracks patient specimens from the time they are collected until the results are reported.
This special technology increases efficiency and improves TAT but cannot ensure quality results.
The quality of results depends on correct procedures being followed in the three phases of the laboratory process: the preexamination (prior to testing) or preanalytical (prior to analysis) phase, the examination (during testing) or analytical (during analysis) phase, and postexamination (after testing) or postanalytical (after analysis) phase.
The terms “preanalytical,” “analytical,” and “postanalytical” have traditionally been used to describe the phases of the testing process.
The CLSI Quality Management Systems (QMS) documents use the term “examination” instead of “analytical” when referring to the process of testing clinical samples.
As laboratories and hospital systems become more quality focused, you will likely see the terms “preexamination,” “examination,” and “postexamination” replacing “preanalytical,” “analytical,” and “postanalytical.”
Unfortunately, it is in the preexamination/preanalytical phase which begins when a patient is assessed and a test is ordered when most laboratory errors occur
Specimen handling and processing is a critical part of this phase.
Correct handling and processing helps ensure that results obtained on a patient specimen accurately reflect the status of that patient.
Improper handling or processing is an error that can render the most skillfully obtained specimen useless or affect the analyte (substance undergoing analysis) or measurand (quantity being measured) in a way that causes erroneous (invalid) or misleading test results that can cause delayed or incorrect patient care.
Proper specimen handling begins when a test is ordered and continues throughout the testing process until results are reported.
This section of the text, however, covers specimen handling once the sample has been properly collected, throughout processing until testing begins, and during storage before and after testing.
Storage after testing is part of the postexamination/postanalytical phase but can become part of the preexamination/preanalytical phase when repeat testing or additional tests are ordered on a specimen, sometimes hours or even days later.

Specimen Handling

It is not always easy to tell when a specimen has been handled improperly.
To ensure delivery of a quality specimen for analysis, it is imperative that all phlebotomists be adequately instructed in this area so that established policies and procedures are followed.
all specimens should be handled according to the standard precautions guidelines outlined in Chapter 3.

Transporting specimens

It is important to handle and transport blood specimens carefully and deliver them as quickly as possible to the laboratory for processing.
A delay in separating the blood cells from the plasma or serum can result in metabolic changes in the sample.
Rough handling and agitation can hemolyze specimens, activate platelets, and affect coagulation tests as well as break collection tubes.
According to CLSI, tubes should be transported vertically with the stopper up to reduce agitation that can cause red cell damage and lead to hemolysis in the specimen.
The upright position also allows the blood to drain away from the tube stopper to minimize the chance of aerosol (a fine mist of specimen) release when the stopper is removed during processing or testing.
In addition, the upright position aids clot formation in serum tubes and prevents the clot from sticking to the stopper.
Blood in contact with tube stoppers in gel tubes may end up in the serum or plasma above the gel barrier after centrifugation.
This can contaminate the specimen with blood cells that can affect test results, and fibrin strands or clots that can cause blockages in instruments.
According to CLSI, nonanticoagulant gel tubes should be placed in an upright position as soon as they have been mixed.

General Transportation Guidelines

Blood specimen tubes are typically placed in biohazard bags or containers for transportation to the laboratory.
CLSI and Occupational Safety and Health Administration (OSHA) guidelines require specimen transport bags to have a biohazard logo, a liquid-tight closure, and a slip pocket for paperwork (e.g., the requisition).
Nonblood specimens should be transported in leak-proof containers with adequately secured lids. If the laboratory is on site, specimens are either hand delivered by the phlebotomist or other HCWs who have collected them, or sent to the laboratory by means of an automated internal transportation system such as a pneumatic tube, vertical track, or robot system.

Automated Transportation Systems

One of the most common means of transporting specimens to the laboratory from other areas of a hospital is a pneumatic tube system (PTS or P-tube).
This type of delivery system consists of a network of long tubes that connect special sending and receiving stations in certain laboratory areas (e.g., specimen processing) to stations located in various areas of the hospital, usually near a nurses station.
The system works by propelling special canister-like carriers through the system tubes using compressed air or partial vacuum.
All specimens transported through a PTS or other type of automated transport system within the facility should be considered biohazards and require strict protocol to prevent potential contamination issues.
Specimens should be packaged correctly in leak-resistant containers, sealed in zipper-type plastic bags to contain spills, and the carrier should be fitted with disposable clear plastic liners in case of leakage.
Carriers must contain foam pads and special padded liners to provide containment and cushioning during transport.

Each facility’s PTS should be carefully evaluated for the effects of shock and vibration on the validity of laboratory test results.

CLSI Guideline GP44-A4 states that in general, tests negatively affected by PTS transport are those influenced by red cell damage and include potassium, plasma hemoglobin, acid phosphatase, and lactate dehydrogenase.
Specimens that must be maintained at body temperature (e.g., cold agglutinin, cryoglobulin) are also not appropriate for PTS transport.
Unless specific documentation already exists, automated transport systems, pneumatic or otherwise, should be evaluated for any effects on laboratory testing.
See CLSI document H21-A5 for specific recommendations regarding specimens for coagulation testing.

Off-Site Transportation

Many patient specimens are delivered to clinical laboratories from off-site locations such as physician offices, clinics, patient service centers, or private homes, or sent from these locations or healthcare facility laboratories to local or regional reference laboratories.

Local Courier or Mobile Phlebotomist

*Specimens transported by a courier or mobile phlebotomist must be in a leak-proof primary container (e.g., blood tube). This container is put in a zip closure plastic bag containing absorbent material such as paper towels, and placed in a plastic or metal cooler or transport box, which is the secondary container

Alternatively, blood specimens can be placed upright in a rack that sits on top of absorbent material in the bottom of the transport box.
The transport box must be closed to avoid spills and contamination in case it is jostled during transportation.
It must also be properly labeled and accompanied by forms containing specimen data and identification.
Care should be taken to protect specimens from the effects of extreme heat or cold.
Vehicles used to transport specimens on a routine basis must be used exclusively for this purpose.
Specimens transported locally are exempt from most other U.S. Department of Transportation (DOT) regulations unless they are known or suspected to be infectious.

Out-of-Area Transportation

*Diagnostic specimens that are transported out of the area by public transportation are covered by U.S. Department of Transportation (DOT), and International Air Transport Association (IATA) regulations for transportation of infectious substances.

DOT and IATA define two categories of infectious substances:
Biological Substance Category A:
Biological Substance Category B:
Category B regulations require all diagnostic specimens transported by public carrier to have triple packaging.
Packaging materials can be purchased that meet DOT requirements.
Diagnostic specimens can pose a danger if shipped improperly.
Specimen processors and other personnel who package “infectious materials” to be transported by public carriers must show proof of training and be certified. Both IATA and DOT offer certification.
DOT can inspect laboratories for compliance with shipping regulations, and severe penalties such as huge fines and even jail time can be imposed on anyone who knowingly or unknowingly violates them.

Time Limits

*All specimens should be transported to the laboratory without delay.

According to CLSI GP44-A4, Procedures for the Handling and Processing of Blood Specimens, serum or plasma should be physically separated from the cells as soon as possible unless there is conclusive evidence that a longer contact time will not contribute to error in test results.
CLSI guideline GP44-A4 sets two hours as the maximum time limit for separating serum and plasma from the cells for the following tests:
catecholamines, homocysteine, lactic acid, and molecular tests targeting RNA (ribonucleic acid).
Studies cited by CLSI show that the two-hour time limit also applies to glucose, ionized calcium, lactate dehydrogenase (LD or LDH), and potassium.
Some labs may have more stringent criteria than the two-hour guideline that CLSI GP44-A4 uses.
Prompt delivery and separation minimize the effects of metabolic processes, such as glycolysis.
According to a 2013 article in the Journal of Environmental and Public Health, results of community outreach studies found that glycolysis by erythrocytes and leukocytes in blood specimens can falsely lower glucose values from 5% to 7% per hour.
Prompt delivery is easily achieved with an on-site lab, as in a hospital setting, but it is not always possible when specimens come to the lab from off-site locations, such as doctors’ offices and nursing homes.
Consequently, off-site locations should have a small processing area where blood specimens for tests that are performed on serum or plasma can be centrifuged and the serum or plasma separated and transferred to a leak-proof secondary container for transport.
Applicable temperature requirements for all specimens as well as any special handling requirements should be maintained until they are turned over to the courier service.

Time Limit Exceptions

STAT or medical emergency specimens take priority over all other specimens and should be transported, processed, and tested immediately.

Ammonia Specimens

Blood Ammonia levels increase rapidly at room temperature. For accurate results, ammonia specimens must be immediately placed in ice slurry or a cooling tray, transported STAT, and separated from the cells within 15 minutes of collection.

Coagulation Specimens

*The acceptable amount of time between coagulation specimen collection and testing depends on the test.

Ideally, PT and PTT (or aPTT) tests should be performed within four hours of specimen collection.
However, according to CLSI, PT specimens can be held at room temperature either centrifuged with the plasma in contact with the cells, or uncentrifuged for up to 24 hours after collection provided the tubes have not been opened.
PT or PTT specimens that have been opened must be tested within four hours.
If time limits for PT and PTT testing cannot be met, the specimen’s platelet-poor plasma (plasma carefully removed without disturbing the buffy coat) can be frozen at –20°C or below for up to two weeks or –70°C for longer storage.
PTT specimens for monitoring unfractionated heparin levels must be centrifuged within one hour of collection and tested within four hours of specimen collection. If time constraints for samples from patients on unfractionated heparin cannot be met, the specimen should be collected in a CTAD (citrate, theophylline, adenosine, and dipyridamole) tube.

Glucose Specimens in Sodium Fluoride Tubes

Glucose specimens drawn in sodium fluoride tubes are stable for 24 hours at room temperature and for up to 48 hours when refrigerated at 4° to 8°C.
However, inhibition of glycolysis may be inadequate in specimens from patients with abnormally high platelet, red blood cell, or white blood cell counts.
*Even in samples with normal blood cell counts, complete inhibition of glycolysis can take as long as four hours, during which time glucose levels can fall as much as 10 \frac{mg}{dL} even in samples with normal blood cell counts.

Pediatric Glucose Specimens

*Glucose specimens from newborn and pediatric patients should be tested as soon as possible because it is difficult to inhibit glycolysis in newborn and pediatric specimens.

Microcollection devices with an appropriate antiglycolytic agent are available for collecting capillary glucose specimens from pediatric patients.

Hematology Specimens

Blood smears made from Ethylenediaminetetraacetic acid (EDTA) specimens must be prepared within one hour of collection to preserve the integrity of the blood cells and prevent artifact formation due to prolonged contact with the anticoagulant.
EDTA specimens for CBCs should be analyzed within 6 hours but are generally stable for 24 hours at room temperature.
EDTA specimens for erythrocyte sedimentation rate (ESR) determinations must be tested within four hours if left at room temperature or within 12 hours if refrigerated.
EDTA specimens for reticulocyte counts are stable up to 6 hours at room temperature and up to 72 hours if refrigerated.

Molecular Test Specimens

*Plasma Preparation Tubes (PPTs) for molecular testing must me transported, processed, and tested as soon as possible because RNA substances/materials are extremely unstable.

If an RNA test must wait to be run in a batch, the plasma can be stored at 4 degrees Celcius but only for 48 Hours.
There are collection tubes with inhibitors that prevent degradation of RNA and DNA (deoxyribonucleic acid