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Phlebotomy

Phlebotomy

Definition

Phlebotomy is the act of drawing or removing blood from the circulatory system through a cut (incision) or puncture in order to obtain a sample for analysis and diagnosis. Phlebotomy is also done as part of the patient's treatment for certain blood disorders.


Purpose

Phlebotomy that is part of treatment (therapeutic phlebotomy) is performed to treat polycythemia vera, a condition that causes an elevated red blood cell volume (hematocrit ). Phlebotomy is also prescribed for patients with disorders that increase the amount of iron in their blood to dangerous levels, such as hemochromatosis, hepatitis B, and hepatitis C. Patients with pulmonary edema may undergo phlebotomy procedures to decrease their total blood volume.

Phlebotomy is also used to remove blood from the body during blood donation and for analysis of the substances contained within it.


Description

Phlebotomy is performed by a nurse or a technician known as a phlebotomist. Blood is usually taken from a vein on the back of the hand or just below the elbow. Some blood tests, however, may require blood from an artery. The skin over the area is wiped with an antiseptic, and an elastic band is tied around the arm. The band acts as a tourniquet, retaining blood within the arm and making the veins more visible. The phlebotomy technician feels the veins in order to select an appropriate one. When a vein is selected, the technician inserts a needle into the vein and releases the elastic band. The appropriate amount of blood is drawn and the needle is withdrawn from the vein. The patient's pulse and blood pressure may be monitored during the procedure.

For some tests requiring very small amounts of blood for analysis, the technician uses a finger stick. A lance, or small needle, makes a small cut in the surface of the fingertip, and a small amount of blood is collected in a narrow glass tube. The fingertip may be squeezed to get additional blood to surface.

The amount of blood drawn depends on the purpose of the phlebotomy. Blood donors usually contribute a unit of blood (500 mL) in a session. The volume of blood needed for laboratory analysis varies widely with the type of test being conducted. Typically one or several small (510 mL) tubes are drawn. Therapeutic phlebotomy removes a larger amount of blood than donation and blood analysis require. Phlebotomy for treatment of hemochromatosis typically involves removing a unit of blood250 mg of irononce a week. Phlebotomy sessions are required until iron levels return to a consistently normal level, which may take several months to several years. Phlebotomy for polycythemia vera removes enough blood to keep the patient's hematocrit (proportion of red blood cells) below 45%. The frequency and duration of sessions depends on the patient's individual needs.

Diagnosis/Preparation

Patients having their blood drawn for analysis may be asked to discontinue medications or to avoid food (to fast) for a period of time before the blood test. Patients donating blood will be asked for a brief medical history, have their blood pressure taken, and have their hematocrit checked with a finger stick test prior to donation.


Aftercare

After blood is drawn and the needle is removed, pressure is placed on the puncture site with a cotton ball to stop bleeding, and a bandage is applied. It is not uncommon for a patient to feel dizzy or nauseated during or after phlebotomy. The patient may be encouraged to rest for a short period once the procedure is completed. Patients are also instructed to drink plenty of fluids and eat regularly over the next 24 hours to replace lost blood volume. Patients who experience swelling of the puncture site or continued bleeding after phlebotomy should seek immediate medical treatment.


Risks

Most patients will have a small bruise or mild soreness at the puncture site for several days. Therapeutic phlebotomy may cause thrombocytosis and chronic iron deficiency (anemia) in some patients. As with any invasive procedure, infection is also a risk. This risk is minimized by the use of prepackaged sterilized equipment and careful attention to proper technique. There is no risk of HIV infection from phlebotomy, since all needles are disposed of after a single use. Arterial blood collection carries a higher risk than venous collection, and is performed by a physician or other specially trained professional. Patients who are anemic or have a history of cardiovascular disease may not be good candidates for phlebotomy.


Normal results

Normal results include obtaining the needed amount of blood with the minimum of discomfort to the patient.

Morbidity and mortality rates

Properly performed, phlebotomy does not carry the risk of mortality. It may cause temporary pain and bleeding, but these are usually easily managed.


Alternatives

Phlebotomy is a necessary medical procedure, and is required for a wide variety of other procedures.


Resources

periodicals

Messinezy, Maria and T. C. Pearson. "Polycythaemia, Primary (Essential) Thrombocythaemia and Myelofibrosis (ABC of Clinical Haematology)." British Medical Journal 314 (22 February 1997): 58790.

Wolfe, Yun Lee. "Case of the Ceaseless Fatigue." Prevention Magazine (July 1997): 8894.


Paula Anne Ford-Martin Richard Robinson

QUESTIONS TO ASK THE DOCTOR



  • How many tubes of blood will you withdraw?

WHO PERFORMS THE PROCEDURE AND WHERE IS IT PERFORMED?



Phlebotomy is usually performed by a phlebotomy technician. Arterial collection may be performed by a physician. Collection occurs in the hospital or outpatient clinic.

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"Phlebotomy." Gale Encyclopedia of Surgery: A Guide for Patients and Caregivers. . Encyclopedia.com. 23 Oct. 2017 <http://www.encyclopedia.com>.

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"Phlebotomy." Gale Encyclopedia of Surgery: A Guide for Patients and Caregivers. . Retrieved October 23, 2017 from Encyclopedia.com: http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/phlebotomy-0

Phlebotomy

Phlebotomy

Definition

Phlebotomy is the act of drawing or removing blood from the circulatory system through a cut (incision) or puncture in order to obtain a sample for analysis and diagnosis. Phlebotomy is also done as part of the patient's treatment for certain blood disorders.

Purpose

Treatment

Phlebotomy that is part of treatment (therapeutic phlebotomy) is performed to treat polycythemia vera, a condition that causes an elevated red blood cell volume (hematocrit ). Phlebotomy is also prescribed for patients with disorders that increase the amount of iron in their blood to dangerous levels, such as hemochromatosis, hepatitis B, and hepatitis C. Patients with pulmonary edema may undergo phlebotomy procedures to decrease their total blood volume.

Diagnosis

Phlebotomy is also used to remove blood from the body during blood donation and for analysis of the substances contained within it.

Precautions

Patients who are anemic or have a history of cardiovascular disease may not be good candidates for phlebotomy.

Description

Phlebotomy, which is also known as venesection, is performed by a nurse or a technician known as a phlebotomist. Blood is usually taken from a vein on the back of the hand or inside of the elbow. Some blood tests, however, may require blood from an artery. The skin over the area is wiped with an antiseptic, and an elastic band is tied around the arm. The band acts as a tourniquet, slowing the blood flow in the arm and making the veins more visible. The patient is asked to make a fist, and the technician feels the veins in order to select an appropriate one. When a vein is selected, the technician inserts a needle into the vein and releases the elastic band. The appropriate amount of blood is drawn and the needle is withdrawn from the vein. The patient's pulse and blood pressure may be monitored during the procedure.

For some tests requiring very small amounts of blood for analysis, the technician uses a finger stick. A lance, or small needle, makes a small cut in the surface of the fingertip, and a small amount of blood is collected in a narrow glass tube. The fingertip may be squeezed to get additional blood to surface.

The amount of blood drawn depends on the purpose of the phlebotomy. Blood donors usually contribute a unit of blood (500 mL) in a session. The volume of blood needed for laboratory analysis varies widely with the type of test being conducted. Therapeutic phlebotomy removes a larger amount of blood than donation and blood analysis require. Phlebotomy for treatment of hemochromatosis typically involves removing a unit of blood-or 250 mg of iron-once a week. Phlebotomy sessions are required until iron levels return to a consistently normal level, which may take several months to several years. Phlebotomy for polycythemia vera removes enough blood to keep the patient's hematocrit below 45%. The frequency and duration of sessions depends on the patient's individual needs.

Preparation

Patients having their blood drawn for analysis may be asked to discontinue medications or to avoid food (to fast) for a period of time before the blood test. Patients donating blood will be asked for a brief medical history, have their blood pressure taken, and have their hematocrit checked with a finger stick test prior to donation.

Aftercare

After blood is drawn and the needle is removed, pressure is placed on the puncture site with a cotton ball to stop bleeding, and a bandage is applied. It is not uncommon for a patient to feel dizzy or nauseated during or after phlebotomy. The patient may be encouraged to rest for a short period once the procedure is completed. Patients are also instructed to drink plenty of fluids and eat regularly over the next 24 hours to replace lost blood volume. Patients who experience swelling of the puncture site or continued bleeding after phlebotomy should get medical help at once.

Risks

Most patients will have a small bruise or mild soreness at the puncture site for several days. Therapeutic phlebotomy may cause thrombocytosis and chronic iron deficiency (anemia) in some patients. As with any invasive procedure, infection is also a risk. This risk can be minimized by the use of prepackaged sterilized equipment and careful attention to proper technique.

Normal results

Normal results include obtaining the needed amount of blood with the minimum of discomfort to the patient.

Resources

PERIODICALS

Wolfe, Yun Lee. "Case of the Ceaseless Fatigue." Prevention Magazine July 1997: 88-94.

KEY TERMS

Finger stick A technique for collecting a very small amount of blood from the fingertip area.

Hemochromatosis A genetic disorder known as iron overload disease. Untreated hemochromatosis may cause osteoporosis, arthritis, cirrhosis, heart disease, or diabetes.

Thrombocytosis A vascular condition characterized by high blood platelet counts.

Tourniquet Any device that is used to compress a blood vessel to stop bleeding or as part of collecting a blood sample. Phlebotomists usually use an elastic band as a tourniquet.

Venesection Another name for phlebotomy.

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"Phlebotomy." Gale Encyclopedia of Medicine, 3rd ed.. . Encyclopedia.com. 23 Oct. 2017 <http://www.encyclopedia.com>.

"Phlebotomy." Gale Encyclopedia of Medicine, 3rd ed.. . Encyclopedia.com. (October 23, 2017). http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/phlebotomy

"Phlebotomy." Gale Encyclopedia of Medicine, 3rd ed.. . Retrieved October 23, 2017 from Encyclopedia.com: http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/phlebotomy

phlebotomy

phle·bot·o·my / fləˈbätəmē/ • n. (pl. -mies) the surgical opening or puncture of a vein in order to withdraw blood or introduce a fluid, or (historically) as part of the procedure of letting blood. DERIVATIVES: phle·bot·o·mist n. phle·bot·o·mize / -ˈbätəˌmīz/ v. ( archaic ).

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"phlebotomy." The Oxford Pocket Dictionary of Current English. . Encyclopedia.com. 23 Oct. 2017 <http://www.encyclopedia.com>.

"phlebotomy." The Oxford Pocket Dictionary of Current English. . Encyclopedia.com. (October 23, 2017). http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/phlebotomy

"phlebotomy." The Oxford Pocket Dictionary of Current English. . Retrieved October 23, 2017 from Encyclopedia.com: http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/phlebotomy

phlebotomy

phlebotomy (venesection) (fli-bot-ŏmi) n. the surgical opening or puncture of a vein in order to remove blood (in the treatment of polycythaemia) or to infuse fluids, blood, or drugs in the treatment of many conditions. See also phlebotomist.

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"phlebotomy." A Dictionary of Nursing. . Retrieved October 23, 2017 from Encyclopedia.com: http://www.encyclopedia.com/caregiving/dictionaries-thesauruses-pictures-and-press-releases/phlebotomy