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In medicine, venipuncture or venepuncture is the process of obtaining intravenous access for the purpose of venous blood sampling (also called ''
phlebotomy Phlebotomy is the process of making a puncture in a vein, usually in the arm, with a cannula for the purpose of drawing blood. The procedure itself is known as a venipuncture, which is also used for intravenous therapy. A person who performs a p ...
'') or intravenous therapy. In healthcare, this procedure is performed by medical laboratory scientists,
medical practitioners A health professional, healthcare professional, or healthcare worker (sometimes abbreviated HCW) is a provider of health care treatment and advice based on formal training and experience. The field includes those who work as a nurse, physician (suc ...
, some
EMTs An emergency medical technician (EMT), also known as an ambulance technician, is a health professional that provides emergency medical services. EMTs are most commonly found working in ambulances. In English-speaking countries, paramedics are ...
,
paramedics A paramedic is a registered healthcare professional who works autonomously across a range of health and care settings and may specialise in clinical practice, as well as in education, leadership, and research. Not all ambulance personnel are p ...
,
phlebotomist Phlebotomy is the process of making a puncture in a vein, usually in the arm, with a cannula for the purpose of drawing blood. The procedure itself is known as a venipuncture, which is also used for intravenous therapy. A person who performs a ...
s, dialysis technicians, and other nursing staff. In
veterinary medicine Veterinary medicine is the branch of medicine that deals with the prevention, management, diagnosis, and treatment of disease, disorder, and injury in animals. Along with this, it deals with animal rearing, husbandry, breeding, research on nutri ...
, the procedure is performed by
veterinarians A veterinarian (vet), also known as a veterinary surgeon or veterinary physician, is a medical professional who practices veterinary medicine. They manage a wide range of health conditions and injuries in non-human animals. Along with this, vet ...
and veterinary technicians. It is essential to follow a standard procedure for the collection of blood specimens to get accurate laboratory results. Any error in collecting the blood or filling the test tubes may lead to erroneous laboratory results. Venipuncture is one of the most routinely performed invasive procedures and is carried out for any of five reasons: # to obtain blood for diagnostic purposes; # to monitor levels of blood components; # to administer therapeutic treatments including medications, nutrition, or chemotherapy; # to remove blood due to excess levels of iron or erythrocytes (
red blood cell Red blood cells (RBCs), also referred to as red cells, red blood corpuscles (in humans or other animals not having nucleus in red blood cells), haematids, erythroid cells or erythrocytes (from Greek ''erythros'' for "red" and ''kytos'' for "holl ...
s); or # to collect blood for later uses, mainly transfusion either in the donor or in another person. Blood analysis is an important diagnostic tool available to clinicians within healthcare. Blood is most commonly obtained from the superficial veins of the upper limb. The
median cubital vein In human anatomy, the median cubital vein (or median basilic vein) is a superficial vein of the upper limb. It lies in the cubital fossa superficial to the bicipital aponeurosis. It connects the cephalic vein and the basilic vein. It becomes promi ...
, which lies within the
cubital fossa The cubital fossa, chelidon, or elbow pit, is the triangular area on the anterior side of the upper limb between the arm and forearm of a human or other hominid animals. It lies anteriorly to the elbow (Latin ) when in standard anatomical position ...
anterior to the elbow, is close to the surface of the skin without many large nerves positioned nearby. Other veins that can be used in the cubital fossa for venipuncture include the
cephalic A head is the part of an organism which usually includes the ears, brain, forehead, cheeks, chin, eyes, nose, and mouth, each of which aid in various sensory functions such as sight, hearing, smell, and taste. Some very simple animals m ...
, basilic, and
median antebrachial vein The median antebrachial vein is a superficial vein of the (anterior) forearm. It arises from - and drains - the superficial palmar venous arch, ascending superficially along the anterior forearm before terminating by draining into either the bas ...
s. Minute quantities of blood may be taken by fingerstick sampling and collected from infants by means of a
heelprick In medicine, some blood tests are conducted on capillary blood obtained by fingerstick (or fingerprick) (or, for neonates, by an analogous heelprick). The site, free of surface arterial flow, where the blood is to be collected is sterilized with ...
or from scalp veins with a
winged infusion needle Butterfly needle A winged infusion set—also known as "butterfly" or "scalp vein" set—is a device specialized for venipuncture: i.e. for accessing a superficial vein or artery for either intravenous injection or phlebotomy. It consists, from f ...
. Phlebotomy (incision into a vein) is also the treatment of certain diseases such as
hemochromatosis Iron overload or hemochromatosis (also spelled ''haemochromatosis'' in British English) indicates increased total accumulation of iron in the body from any cause and resulting organ damage. The most important causes are hereditary haemochromatos ...
and primary and secondary
polycythemia Polycythemia (also known as polycythaemia) is a laboratory finding in which the hematocrit (the volume percentage of red blood cells in the blood) and/or hemoglobin concentration are increased in the blood. Polycythemia is sometimes called eryth ...
.


Complications

A 1996 study of blood donors (a larger needle is used in blood donation than in routine venipuncture) found that 1 in 6,300 donors sustained a nerve injury.


Equipment

There are many ways in which blood can be drawn from a vein, and the method used depends on the person's age, the equipment available, and the type of tests required. Most
blood collection In medicine, sampling is gathering of matter from the body to aid in the process of a medical diagnosis and/or evaluation of an indication for treatment, further medical tests or other procedures. In this sense, the sample is the gathered matter ...
in the US, UK, Canada and Hong Kong is done with an evacuated tube system. Two common systems are
Vacutainer A vacutainer blood collection tube is a sterile glass or plastic test tube with a colored rubber stopper creating a vacuum seal inside of the tube, facilitating the drawing of a predetermined volume of liquid. Vacutainer tubes may contain addit ...
(Becton, Dickinson and company) and Vacuette (Greiner Bio-One). The equipment consists of a plastic adapter, also known as a tube or needle holder/hub, a hypodermic needle and a vacuum tube. Under certain circumstances, a syringe may be used, often with a
butterfly needle Butterfly needle A winged infusion set—also known as "butterfly" or "scalp vein" set—is a device specialized for venipuncture: i.e. for accessing a superficial vein or artery for either intravenous injection or phlebotomy. It consists, from f ...
, which is a plastic catheter attached to a short needle. In the developing world, the evacuated tube system is the preferred method of drawing blood.


With evacuated or vacuum tubes

Greiner Bio-One manufactured the first ever plastic evacuated blood collection tube in 1985 under the VACUETTE brand name. Today, many companies sell vacuum tubes as the patent for this device is now in the public domain. These tubes are manufactured with a specific volume of gas removed from the sealed tube. When a needle from a hub or transfer device is inserted into the stopper, the tube's vacuum automatically pulls in the required volume of blood. The basic Evacuated Tube System (ETS) consists of a needle, a tube holder, and the evacuated tubes. The needle is attached to the tube holder by the phlebotomist prior to collection, or may come from the manufacturer as one unit. The needle protrudes through the end of the tube holder, and has a needle on each end. After first cleaning the venipuncture site and applying a tourniquet, the phlebotomist uncaps the needle attached to the tube holder, inserts the needle into the vein, then slides evacuated tubes into the tube holder, where the tube's stopper is pierced by the back end of the needle. The vacuum in the tube then automatically draws the needed blood directly from the vein. Multiple vacuum tubes can be attached to and removed in turn from a single needle, allowing multiple samples to be obtained from a single procedure. This is possible due to the multiple sample sleeve, which is a flexible rubber fitting over the posterior end of the needle
cannula A cannula (; Latin meaning 'little reed'; plural or ) is a tube that can be inserted into the body, often for the delivery or removal of fluid or for the gathering of samples. In simple terms, a cannula can surround the inner or outer surfaces ...
which seals the needle until it is pushed out of the way. This keeps blood from freely draining out of the back of the needle inserted in the vein, as each test tube is removed and the next impaled.
OSHA OSHA or Osha may refer to: Work * Occupational Safety and Health Administration, a federal agency of the United States that regulates workplace safety and health * Occupational Safety and Health Act (United States) of 1970, a federal law in the Un ...
safety regulations require that needles or tube holders come equipped with a safety device to cover the needle after the procedure to prevent accidental needle stick injury. Fittings and adapters used to fill evacuated tubes from butterfly needle kits and syringes are also available. There are several needle gauges for a phlebotomist to choose from. The most commonly used are as follows: a 21g (green top) needle, a 22g (black top) needle, a 21g (green label) butterfly needle, a 23g (light blue label) butterfly needle, and a 25g (orange or dark blue label) butterfly needle (however this needle is only used in pediatrics or extreme cases as it is so small that it can often result in hemolyzing the blood sample). There are also a variety of tube and bottle sizes and volumes for different test requirements.


Additives and order of draw

The test tubes in which blood is collected may contain one or more of several additives. In general, tests requiring whole blood call for blood samples collected in test tubes containing some form of the anticoagulant
EDTA Ethylenediaminetetraacetic acid (EDTA) is an aminopolycarboxylic acid with the formula H2N(CH2CO2H)2sub>2. This white, water-soluble solid is widely used to bind to iron (Fe2+/Fe3+) and calcium ions (Ca2+), forming water-soluble complexes ev ...
. EDTA
chelates Chelation is a type of bonding of ions and molecules to metal ions. It involves the formation or presence of two or more separate coordinate bonds between a polydentate (multiple bonded) ligand and a single central metal atom. These ligands are ...
calcium to prevent clotting. EDTA is preferred for hematology tests because it does minimum damage to cell morphology. Sodium citrate is the anticoagulant used in specimens collected for coagulation tests. The majority of chemistry and immunology tests are performed on serum, which is produced by clotting and then separating the blood specimen via centrifuge. These specimens are collected in either a non-additive tube or one containing a
clotting Coagulation, also known as clotting, is the process by which blood changes from a liquid to a gel, forming a blood clot. It potentially results in hemostasis, the cessation of blood loss from a damaged vessel, followed by repair. The mechanism o ...
activator. This clotting activator can interfere with some assays, and so a plain tube is recommended in these cases, but will delay testing. Tubes containing lithium heparin or sodium heparin are also commonly used for a variety of chemistry tests, as they do not require clotting and can be centrifuged immediately after collection. A combination of
sodium fluoride Sodium fluoride (NaF) is an inorganic compound with the formula . It is used in trace amounts in the fluoridation of drinking water, in toothpaste, in metallurgy, and as a flux. It is a colorless or white solid that is readily soluble in water. I ...
and potassium oxalate is used for glucose tests, as these additives both prevent clotting and stop glycolosis, so that blood glucose levels are preserved after collection. Another specialty tube is an opaque amber colored tube used to collect blood for light sensitive analytes, such as bilirubin. Test tubes are labeled with the additive they contain, but the stopper on each tube is color coded according to additive as well. While colors vary between manufacturers, stopper colors generally are associated with each additive as listed below. Because the additives from each tube can be left on the needle used to fill the tubes, they must be drawn in a specific order to ensure that cross contamination will not negatively affect testing of the samples if multiple tubes are to be drawn at once. The "order of draw" varies by collection method. Below in the order of draw generally required for the Evacuated Tube System (ETS) collection method are the most common tubes, listing additive and color:


In children

Use of lidocaine iontophoresis is effective for reducing pain and alleviating distress during venipuncture in children. A needle-free powder
lignocaine Lidocaine, also known as lignocaine and sold under the brand name Xylocaine among others, is a local anesthetic of the amino amide type. It is also used to treat ventricular tachycardia. When used for local anaesthesia or in nerve blocks, lidoca ...
delivery system has been shown to decrease the pain of venipuncture in children. Rapid dermal anesthesia can be achieved by local anesthetic infiltration, but it may evoke anxiety in children frightened by needles or distort the skin, making vascular access more difficult and increasing the risk of needle exposure to health care workers. Dermal anesthesia can also be achieved without needles by the topical application of local anesthetics or by lidocaine iontophoresis. By contrast, noninvasive dermal anesthesia can be established in 5–15 min without distorting underlying tissues by lidocaine iontophoresis, where a direct electric current facilitates dermal penetration of positively charged lidocaine molecules when placed under the positive electrode. One study concluded that the iontophoretic administration of lidocaine was safe and effective in providing dermal anesthesia for venipuncture in children 6–17 years old. This technique may not be applicable to all children. Future studies may provide information on the minimum effective iontophoretic dose for dermal anesthesia in children and the comparison of the anesthetic efficacy and satisfaction of lidocaine iontophoresis with topical anesthetic creams and subcutaneous infiltration. Non-pharmacological treatments for pain associated with venipuncture in children includes
hypnosis Hypnosis is a human condition involving focused attention (the selective attention/selective inattention hypothesis, SASI), reduced peripheral awareness, and an enhanced capacity to respond to suggestion.In 2015, the American Psychologica ...
and distraction. These treatments reduced self reported pain and when combined with
cognitive-behavioural therapy Cognitive behavioral therapy (CBT) is a psycho-social intervention that aims to reduce symptoms of various mental health conditions, primarily depression and anxiety disorders. CBT focuses on challenging and changing cognitive distortions (suc ...
(CBT) the reduction of pain was even greater. Other interventions have not been found to be effective and these are suggestion, blowing out air, and distraction with parent coaching did not differ from control for pain and distress.


With needle and syringe

Some health care workers prefer to use a syringe-needle technique for venipuncture. ''Sarstedt'' manufactures a blood-drawing system (S-Monovette) that uses this principle. This method can be preferred on the elderly, those with cancer, severe burns, obesity, or where the veins are unreliable or fragile. Because syringes are manually operated, the amount of suction applied may be easily controlled. This is particularly helpful when veins are small which may collapse under the suction of an evacuated tube. In children or other circumstances where the quantity of blood gained may be limited it can be helpful to know how much blood can be obtained before distributing it amongst the various additives that the laboratory will require. Another alternative is drawing blood from indwelling cannulae.


Blood cultures

There are times when a blood culture collection is required. The culture will determine if there are pathogens in the blood. Normally blood is sterile. When drawing blood from cultures use a sterile solution such as
Betadine Povidone-iodine (PVP-I), also known as iodopovidone, is an antiseptic used for skin disinfection before and after surgery. It may be used both to disinfect the hands of healthcare providers and the skin of the person they are caring for. It may a ...
rather than alcohol. This is done using sterile gloves, while not wiping away the surgical solution, touching the puncture site, or in any way compromising the sterile process. It is vital that the procedure is performed in as sterile a manner as possible as the persistent presence of skin
commensal Commensalism is a long-term biological interaction (symbiosis) in which members of one species gain benefits while those of the other species neither benefit nor are harmed. This is in contrast with mutualism, in which both organisms benefit fro ...
s in blood cultures could indicate
endocarditis Endocarditis is an inflammation of the inner layer of the heart, the endocardium. It usually involves the heart valves. Other structures that may be involved include the interventricular septum, the chordae tendineae, the mural endocardium, or the ...
but they are most often found as contaminants. It is encouraged to use an abrasive method of skin preparation. This removes the upper layers of dead skin cells along with their contaminating bacteria. Povidone-iodine has traditionally been used but in the UK a 2%
chlorhexidine Chlorhexidine (CHX) (commonly known by the salt forms chlorhexidine gluconate and chlorhexidine digluconate (CHG) or chlorhexidine acetate) is a disinfectant and antiseptic that is used for skin disinfection before surgery and to sterilize surgi ...
in 70% ethanol or isopropyl alcohol solution is preferred and time must be allowed for it to dry. The tops of any containers used when drawing a blood culture should also be disinfected using a similar solution. Some labs will actively discourage iodine use where iodine is thought to degrade the rubber stopper through which blood enters the bottle, thus allowing contaminates to enter the container. The blood is collected into special transport bottles, which are like vacuum tubes but shaped differently. The blood culture bottle contains transport media to preserve any microorganisms present while they are being transported to the laboratory for cultures. Because it is unknown whether the pathogens are
anaerobic Anaerobic means "living, active, occurring, or existing in the absence of free oxygen", as opposed to aerobic which means "living, active, or occurring only in the presence of oxygen." Anaerobic may also refer to: * Anaerobic adhesive, a bonding a ...
(living without oxygen) or
aerobic Aerobic means "requiring air," in which "air" usually means oxygen. Aerobic may also refer to * Aerobic exercise, prolonged exercise of moderate intensity * Aerobics, a form of aerobic exercise * Aerobic respiration, the aerobic process of cel ...
(living with oxygen), blood is collected to test for both. The aerobic bottle is filled first, and then the anaerobic bottle is filled. However, if the collection is performed using a syringe, the anaerobic bottle is filled first. If a butterfly collection kit is used, the aerobic bottle is filled first, so that any air in the tubing is released into the oxygen-containing bottle. Specially designed blood culture collection bottles eliminate the need for either the syringe or butterfly collection method. These specially designed bottles have long necks that fit into the evacuated tubes holders that are use for regular venipuncture collection. These bottles also allow for collection of other blood specimens via evacuated tubes, to be collected without additional venipuncture. The amount of blood that is collected is critical for the optimal recovery of microorganisms. Up to 10mL of blood is typical, but can vary according to the recommends of the manufacturer of the collection bottle. Collection from infants and children are 1 to 5 mL. If too little blood is collected, the ratio of blood-to-nutrient broth will inhibit the growth of microorganisms. If too much blood is collected, there is the risk of a hospital-induced anemia and the ratio of blood-to-nutrient broth will tilt in the opposite direction, which also is not conductive to optimal growth. The bottles are then incubated in specialized units for 24 hours before a lab technician studies and/or tests it. This step allows the very small numbers of bacteria (potentially 1 or 2 organisms) to multiply to a level which is sufficient for identification +/-antibiotic resistance testing. Modern blood culture bottles have an indicator in the base which changes color in the presence of bacterial growth and can be read automatically by machine. (For this reason the barcoded stickers found on these bottles should not be removed as they are used by the laboratory's automated systems.)


Taking blood samples from animals

Blood samples from living laboratory animals may be collected using following methods: * Blood collection not requiring anesthesia: ** Saphenous vein (rat, mice, guinea pig) ** Dorsal pedal vein (rat, mice) * Blood collection requiring anesthesia (local/general anesthesia): ** Tail vein (rat, mice) ** Tail snip (mice) ** Orbital sinus (rat, mice) ** Jugular vein (rat, mice) ** Temporary cannula (rat, mice) ** Blood vessel cannulation (guinea pig, ferret) ** Tarsal vein (guinea pig) ** Marginal ear vein or artery (rabbit) * Terminal procedure: ** Cardiac puncture (rat, mice, guinea pig, rabbit, ferret) ** Orbital sinus (rat, mice) ** Posterior vena cava (rat, mice) The volume of the blood sample collection is very important in experimental animals. All nonterminal blood collection without replacement of fluids is limited up to 10% of total circulating blood volume in healthy, normal, adult animals on a single occasion and collection may be repeated after three to four weeks. In case repeated blood samples are required at short intervals, a maximum of 0.6 ml/kg/day or 1.0% of an animal's total blood volume can be removed every 24 hours. The estimated blood volume in adult animals is 55 to 70 ml/kg body weight. Care should be taken for older and obese animals. If blood collection volume exceeds more than 10% of total blood volume, fluid replacement may be required. Lactated Ringer's solution (LRS) is recommended as the best fluid replacement by National Institutes of Health (NIH). If the volume of blood collection exceeds more than 30% of the total circulatory blood volume, adequate care should be taken so that the animal does not develop hypovolemia.


Blood alcohol tests

It is generally not advisable to use
isopropyl alcohol Isopropyl alcohol (IUPAC name propan-2-ol and also called isopropanol or 2-propanol) is a colorless, flammable organic compound with a pungent alcoholic odor. As an isopropyl group linked to a hydroxyl group ( chemical formula ) it is the s ...
to cleanse the venipuncture site when obtaining a specimen for a
blood alcohol Blood alcohol content (BAC), also called blood alcohol concentration or blood alcohol level, is a measurement of alcohol intoxication used for legal or medical purposes; it is expressed as mass of alcohol per volume or mass of blood. For exampl ...
test. This has been related largely to the potential legal implications associated with the use of alcohol-based cleaners that could theoretically impact analysis. Numerous police alcohol collection kits have been marketed that incorporate a sodium fluoride/potassium oxalate preservative and non-alcohol-based cleansing agents to ensure proper collection. Using soap and hot water or a
povidone-iodine Povidone-iodine (PVP-I), also known as iodopovidone, is an antiseptic used for skin disinfection before and after surgery. It may be used both to disinfect the hands of healthcare providers and the skin of the person they are caring for. It may ...
swab are advisable alternatives to isopropyl alcohol in this case.


See also

*
Arterial blood Arterial blood is the oxygenated blood in the circulatory system found in the pulmonary vein, the left chambers of the heart, and in the artery, arteries. It is bright red in color, while venous blood is dark red in color (but looks purple through ...
is taken from an artery instead of a vein


References

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