A partnership project of Ministry of Health & Family Welfare and U.S. Centers for Disease Control

FAQs: Preanalytical

1.What is a TRF?

TRF is the laboratory Test Request Form generated at the time of registration and it ensures all the data enumerated as per the ISO151989:2012. Every request for tests should be accompanied by a written form which includes patient identification, including gender, date of birth, and the location/contact details of the patient, and a unique identifier; name or other unique identifier of clinician, healthcare provider, or other person legally authorized to request examinations or use medical information, together with the destination for the report and contact details, type of primary sample and, where relevant, the anatomic site of origin; examinations requested, clinically relevant information about the patient and the request, for examination performance and result interpretation purposes. Information needed for examination performance and results interpretation must be asked for and may include the patient’s ancestry, family history, travel and exposure history, communicable diseases, history of medication and other clinically relevant information.

2.What is traceability of samples and unique identifiers?

A system of identification and tracking is essential to ensure that the sample is correctly matched with the result and with the patient or donor.It is done through unique numbering / labeling of samples that can be traced back to the correct patients.Unique identifiersare important tools for managing information, and careful thought should be given for how best to assign identifiers to patients and sampleswithin the information management system.

3.What is Informed Consent?

All procedures carried out on a patient need the informed consent of the patient. For most routine laboratory procedures, consent can be inferred when the patient presents himself or herself at a laboratory with a request form and willingly submits to the usual collecting procedure, for example, venipuncture. Patients in a hospital bed should normally be given the opportunity to refuse.
Special procedures, including more invasive procedures, or those with an increased risk of complications to the procedure, will need a more detailed explanation and, in some cases, written consent. It is also applicable where legalities are concerned. In emergency situations, consent might not be possible; under these circumstances it is acceptable to carry out necessary procedures, provided they are in the patient’s best interest.

4.Why are pre-collection guidelines required?

Several changes in values can happen due to physiological variables. Examples of physiological variations include food intake, circadian rhythms, travel, sweating, prolonged bed rest, posture, environmental factors and seasonal influences. A few precautions are suggested to ensure best results. Fasting and loading tests, patient collected samples etc. require appropriate directions to the patient.

5.What do you mean by quality and integrity of samples?

The sample should be maintained in proper condition that would result in necessary preservation in order to ensure that theanalyte being quantifies is preserved optimally and quality of the results is satisfactory.

6.What are Closed-collection Systems?

Closed or evacuated systems are those which use needles to fill the tubes directly where the vacuum in the tube enables the filling of the tube. Such needles have a patient end that is used for puncturing the vein and a non-patient end that is pushed into the evacuated collection tube. The system is held in place with a holder that makes administration easy. Such systems are preferable because they have been proven to be safer than open systems and provide better specimen quality. The added advantage of using closed system is that blood comes directly in contact with the anticoagulant avoiding many pre-analytical issues such as micro-clot formation.

7.Why and what is the Choice of Gauge of needles? How do you know which needle is which?

If the needle is too large for the vein for which it is intended, it will tear the vein and cause bleeding (haematoma). Also, if the needle is too large blood enters tube faster and forcefully and may results in hemolysis. If the needle is too small, it will damage the blood cells during sampling, and laboratory tests that require whole blood cells, and tests such as K+, Bilirubin, LDH etc. that get affected due to hemolysis, will be invalid. Generally 21- 23 gauge needle is used. All needles are color coded for easy identification.

8.What are the common sites for venipuncture?

A. Ante Cubical area

  1. Median cubical vein (Most preferred site)
  2. Cephalic vein (next preferred)
  3. Basilica vein (3rd preferred)

B. Dorsum of the hand

Median cubital vein: It is the most preferred site as it is large, well anchored, least painful and least likely to bruise. Cephalic vein is next preferred site. It is large but not well anchored and may be more painful than Median cubital. Basilic vein is the third choice. It is generally large, easy to palpate but not well anchored. It involves the greatest risk as it lies near brachial artery and the median nerve either of each can be easily punctured.The veins on the dorsum of the hand have a greater tendency to bleed. In fat persons however, it may be difficult to access an ante-cubital veins; in them the veins in the dorsum of the hand are easier to reach.

9.Why is there an order of draw?

Several tubes contain clot activators and additives that will interfere with some tests for which other tubes are used. Some tests cannot afford any contamination. Hence the “Order of Draw”. The blood collection tube is drawn first to avoid contamination. The Coagulation tubes come next to avoid contact with the clot activators in serum tubes. The EDTA tube is drawn after serum tubes to avoid interference of the Potassium salts in EDTA in the serum tubes as Potassium is an analyte that is checked using serum.

10.Why are some inversions specified in each tube?

In most tubes, the clot activators or additives are in powder form and needs enough inversions to get mixed well. Since active shaking will lyse RBCs resulting in artifacts, gently inversions as required is specified with each tube

11.What is a non-conforming event and an incident? What is an NCE/ incident reporting system?

When a protocol is written down in an SOP/QSP in accordance with standards and guidelines, it needs to be adhered to. This is called Conformance. When a set rule is violated, it is called Non-Conformance (NC)/ Non-Conforming Event (NCE).
An incident is that which occurs unplanned, e.g. Needle Stick Injuries. A major incident can be called an accident, e.g. a fire
If a needle-stick happens to a worker, it is an incident. If the post exposure prophylaxis (PEP) s not followed as per the set guidelines of the lab it is an NCE.
A system is required for reporting all NCE/Incident/Accident/adverse events. A log book or register should be prepared with accurate details of the NCE/incident/ Accident, possible cause and management (corrective and preventive action) of adverse events. This can form the basis of continual improvement of a lab

12.What are the common Non-conforming events in Sample collection?

Laboratories produce test results that are widely used in clinical and public health settings, and health outcomes depend on the accuracy of the testing and reporting. 68% of lab errors are reportedly due to pre-analytical errors. One of the common causes is hemolysis. Trauma to patients, lack of infection control precautions that lead to HAIs for the patients and staff, improper BMW disposal leading to infections as well as environmental degradation are all part of NCEs in collection

13.What are the personal protective equipments (PPE) and infection control aids in sample collection?

In general PPE include: well fitting Latex gloves (Or equivalent if allergic), Mask, goggles or a face shield, Gown/aprons, Head covering. PPEs are to protect the healthcare worker form biological hazards Infection control aids - Hand Hygiene materials (Soap and Water or alcohol rub), single-use disposable needles, syringes, lancing devices and tubes. The infection control aids are to protect the healthcare worker, patients and environment from biological hazards

14.What is PEP?

Post exposure prophylaxis (PEP) refers to comprehensive medical management to minimize the risk of infection among Health Care Personnel (HCP) following potential exposure to blood-borne pathogens (HIV, HBVand HCV)

15.What are the types of exposure?

Types of exposure are as follows.

Mild exposure: mucous membrane/non-intact skin with small volumesE.g. a superficial wound (erosion of the epidermis) with a plain or low calibre needle/contact with the eyes or mucous membranes, subcutaneous injections following small-bore needles

Moderate exposure:mucous membrane/non intact skin with large volumes OR percutaneous superficial exposure with solid needle. E.g. a cut or needle sticks injury penetrating gloves

Severe exposure: percutaneous with large volume E.g.: an accident with a high calibre needle (>18 G) visibly contaminated with blood; a deep wound (haemorrhagic wound and/or very painful); transmission of a significant volume of blood; an accident with material that has previously been used intravenously or intra-arterially

16.What is DBS?

DBS is commonly known as Dried Blood Spot. These are blood spot on special filter papers. It offers ease of specimen collection and transportation through post. This is utilized for variety of tests like, early infant diagnosis (EID), HIV viral load and IBBS- HIV sentinel surveillance.

17.What is TAT?

Turnaround time (TAT) is the total time taken between the sampling of patient, to do the testing and to test reporting to the patient

18.What is BMW?

Biomedical waste means any waste, which is generated during the diagnosis, treatment or immunization of human beings or animals or in research activities pertaining there to or in the production or testing of biological or in health camps & including categories mentioned in Schedule I appended to BMWM Rules, 2016.

19.Where and by whom are samples collected?

The answer depends on the type of samples collected. Blood samples are usually collected in the lab or in the patient’s bedside (ward/ homes as the case may be), generally by technicians. Some blood analytes are labile and require special collection. E.g. Blood gases.
Some samples are patient collected, e.g. urine, stool, sputum, semen. Special collection instructions and containers should be provided to the patient regarding these collections. Mechanism for handling and transport should be adequately explained
Some samples like cavity fluids, cytology and histopathology samples are collected by doctors either at the bedside/ operation theatres. Special guidelines should be provided to these staff regarding the collection, handling and transportation.
Some samples such as microbiology samples require special techniques in collection and handling.

20.Why is a Sample Collection Manual required? What all information should it contain?

The answer to Q: 19, shows the variety of samples processed by a lab. As different samples require, different collection, handling and transportation requirement, it is optimal that these are compiled and made available at all points of collection.
The Sample Collection Manual should ideally contain the following; process of establishment and review of service agreements (billing, registration etc.), information for patients and users, instructions for pre-collection activities, instructions for collection activities, sample transportation, sample reception, pre-examination handling, preparation and storage, managing and reporting adverse incidents, and Bio Medical Waste management. A sample collection manual is a requirement of ISO 15189
For more on this see the Sample Collection and Pre-analytical Best Practices module of Labs for Life