Collection Procedures

Phlebotomy, also known as venesection, is performed by a nurse or a technician known as a phlebotomist. Blood is usually taken from a vein in the upper forearm (antecubetal fossa) is most often chosen for venipuncture. Arterial blood is required for blood gas measurements. Smaller quantity of blood may be obtained from the capillary bed by puncture of the skin – a capillary puncture or skin puncture. Capillary blood is often used for point of care tests (POCT).

There are many ways in which blood can be drawn from a vein. The best method depends on the age and condition of the patient, equipment available and tests required. The veins generally used for venipuncture are those in the forearm, wrist, or ankle. Blood is most commonly obtained from the veins in the forearm since they are larger and more fuller. There are three main veins in forearm – cephalic, median cubital, and median basilic. Usually median cubital vein in the forearm is chosen for venipuncture.

An evacuated tube and needle collection system or a sterile syringe and needle can be used for collection of blood from a vein. BD Vacutainer system tubes are widely used where BD represents the company Becton, Dickinson and company, which first marketed these tubes. Evacuated tubes can be combined to use in an infusion or butterfly set.

In the evacuated tube method, the hypodermic needle used to puncture the vein is double ended, the second shorter needle being shrouded for safety by the holder. One end of a two-way needle is partially attached by means of a holder to the rubber stopper of a specially prepared vacuum tube, while the other end of the needle is inserted into the vein. When a Vacutainer test tube is pushed down into the holder, its rubber cap is pierced by the second needle and the pressure difference between the blood volume and the vacuum in the tube forces blood through the needle and into the tube. The filled tube is then removed and another can be inserted and filled the same way. It is important to remove the tube before withdrawing the needle, as there may still be some suction left, causing pain upon withdrawal. The Clinical and Laboratory Standards Institute (formerly NCCLS) has published standards for use of evacuated tubes for blood specimen collection.

In patients with difficult veins the use of a syringe and needle system is made for collection of blood. Vacuum of BD vacutainer tubes may cause collapsing of smaller veins in some patients, and in this case use of syringe and needle is preferred. In case of collection for babies, and small children with small veins, for obese patients with hard to find veins, for patients receiving intravenous therapy with scarred veins, and for veins other than those in antecubital fossa (wrist, back of hand, ankle, foot, or scalp), an infusion set called butterfly is often used.

The duties as a phlebotomist of technicians vary depending on the workplace. In a hospital, the phlebotomist’s primary duty is to assist doctors. The technician also coordinates with nurses. One of the duties as a phlebotomist of a hospital technician is to take blood or tissue samples from patients.

Even before sample collection, patient identification is the first job of the phlebotomist. Taking blood specimens by correct puncture or incision is the duty of the phlebotomist cum hospital technician. Appropriate volume of blood should be collected as per the tests required and it is also the responsibility of the phlebotomist. Proper and accurate labeling of the samples is also another aspect of job of a hospital technician. Properly labeled samples should be promptly delivered to the testing laboratory which is ensured by the technician.

Phlebotomists can complete either on job training, cross train from another health care profession, or a formal program from phlebotomy training schools to attain these competencies. Phlebotomy certification from professional associations leads to skill refinement and continuous education for practicing phlebotomists.

Written by Phlebotomy Training specialist Dr Shahbaz A. Cheema, Course Director for Maxis Healthcare who run NHS Accredited Phlebotomy Training courses for medical and non medical practitioners. Learn the 3 Steps To Become a Phlebotomist

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