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Answering your questions: EDTA "pink top" tube for blood bank.



Q I recently read in my immunohematology textbook, Immunohematology principles and practice, 2nd ed., by Eva D. Quinley, and have heard in a recent lecture that the preferred specimen for ABO ABO

See: Accumulated Benefit Obligation
 and Rh typing is non-anticoagulated specimen, or one anticoagulated with heparin heparin (hĕp`ərĭn), anticoagulant produced by cells in many animals. A polysaccharide, heparin is found in the human body and occurs in greatest concentration in the tissues surrounding the capillaries of the lungs and the liver.  in order to preserve complement. My question is how did the standard blood-collection tube for blood bank become the EDTA EDTA: see chelating agents.  "pink top" tube? EDTA binds calcium and thereby inhibits complement activation.

[ILLUSTRATION OMITTED]

A According to according to
prep.
1. As stated or indicated by; on the authority of: according to historians.

2. In keeping with: according to instructions.

3.
 American Association American Association refers to one of the following professional baseball leagues:
  • American Association (19th century), active from 1882 to 1891.
  • American Association (20th century), active from 1902 to 1962 and 1969 to 1997.
 of Blood Banking standards (22nd ed.), either plasma or serum can be used for pretransfusion testing. (1) While transfusion-service use of EDTA samples is not yet "the standard," it is becoming more popular for a number of reasons. Serum that is incompletely clotted can yield spurious results, and serum-separator tubes that accelerate clotting clotting /clot·ting/ (klot´ing) coagulation (1).

clotting

the formation of a jellylike substance over the ends or within the walls of a blood vessel, with resultant stoppage of the blood flow.
 cannot be used for transfusion testing. Given the need for rapid turnaround, waiting for specimens to clot is a delay that many trauma patients cannot afford. Patients on anticoagulants Anticoagulants
Drugs that suppress, delay, or prevent blood clots. Anticoagulants are used to treat embolisms.

Mentioned in: Embolism, Heart Valve Replacement
 can also experience significant delays in getting blood ready because of prolonged clotting times. A major advantage with using EDTA is that testing can begin as soon as the specimen arrives in the lab, with no waiting for clotting. As the questioner implies, the concern with using EDTA-stabilized specimens is that there are clinically significant antibodies that can be detected only when activated complement is present (especially J[k.sup.a] and J[k.sup.b]). By blocking complement activation, EDTA impairs our ability to detect these antibodies. While this is a well-recognized limitation of EDTA, most clinically significant non-A, -B, -O antibodies are IGG molecules; and we are not reliant solely on complement for their detection. The increased use of gel-/solid-phase methods for antibody testing has increased interest in use of EDTA because these methods seem to perform more reliably when plasma is used. (2) Validation studies and clinical trials done over the last decade have shown that the combination of EDTA-stabilized specimens, monospecific monospecific /mono·spe·cif·ic/ (mon?o-spe-sif´ik) having an effect only on a particular kind of cell or tissue or reacting with a single antigen, as a monospecific antiserum.  IGG reagents, and gel-/solid-phase testing is fast, safe, and reliable. (3)

While no perfect method for antibody screening has yet been found, many blood bankers have concluded that EDTA is a practical compromise

that meets the needs of most patients.

"Our labs are much more than technology. They are the dedicated people who go the extra mile to provide service to our patients. Keep up the good work."--Daniel M. Baer, MD, MLO MLO Mycoplasma-like organism(s)  editorial advisory board

References

(1.) Menitove JE, ed. Standards for Blood Banks and Transfusion Services. 22nd ed. Bethesda, MD: American Association of Blood Banks; 2003.

(2.) Scott Y. Comparison of plasma and serum for antibody detection using DiaMed microtubes. Transfus Med. 1996;6(1)65.

(3.) Titlestad K. Detection of irregular red cell antibodies: more than 3 years of experience with a gel technique and pooled screening cells. Vox Sang. 1997;73(4):246-251.

Edited by Daniel M. Baer, MD

--Richard M. Scanlan, MD

Director, Transfusion Medicine transfusion medicine Blood banking A subspecialty of clinical pathology or internal medicine which is involved in Pt management through administration of blood cells and blood products including fresh-frozen plasma and cryoprecipitate; TM specialists are versant in  

Oregon Health and Science University

Portland, OR

MLO's "Tips from the Clinical Experts" provides practical, up-to-date solutions to readers' technical and clinical issues from a panel of experts in various fields. Readers may send questions to Dan Baer by e-mail at tips@mlo-online.com.

Daniel M. Baer, MD, is professor emeritus of laboratory medicine at Oregon Health and Science University in Portland, OR, and a member of MLO's editorial advisory board.
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Title Annotation:Tips from the clinical experts
Author:Scanlan, Richard M.
Publication:Medical Laboratory Observer
Article Type:Column
Date:Apr 1, 2006
Words:560
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