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Answering your questions.

Standards for transporting specimens

Q What are the standards for transporting blood and body fluid from doctors' offices and nursing homes to the laboratory by our courier?

A The U.S. Department of Transportation (DOT), the U.S. Postal Service (USPS), international agencies, and shipping carriers have established detailed requirements for packaging and shipping blood and body fluids from humans and animals, designed to prevent hazardous leaks and spills. Materials carried by a lab or hospital courier are an "exception" in the DOT rules. They do not need to follow some of the labeling and marking requirements.

Material--other than Risk Group 4 (highly infectious) material--that is a diagnostic specimen, a biological product, or regulated medical waste must be contained in two-part combination packaging. For liquids, the inner packaging must be leak-tight, and the outer packaging must contain sufficient absorbent material for the entire contents of the inner packaging. A spill kit containing absorbent material, a chlorine disinfectant, a leak-proof waste disposal container, and heavy-duty reusable gloves should be kept in the transport vehicle.

A courier transporting specimens from a doctor's office or clinic to a laboratory should follow these minimum standards:

* Specimen containers should be water-tight and leak-proof;

* If the specimen container is a tube, it must be tightly capped and placed in a rack to maintain it in an upright position;

* The inner packaging must be leak-tight, and the outer packaging must contain sufficient absorbent material to absorb the entire contents of the inner packaging;

* Specimen containers and racks should be placed in robust, leakproof plastic or metal transport boxes with secure, tight-fitting covers;

* The transport box should be secured in the transport vehicle;

* Each transport box should be appropriately labeled consistent with its contents; and

* Specimen data forms and identification data should accompany each transport box.

The Oregon State Public Health Laboratory-Laboratory Response Network has prepared a computer-based training program on packaging and shipping of lab specimens. It provides current DOT, Centers for Disease Control and Prevention, USPS, and international regulations on packaging and shipping of diagnostic specimens and infectious substances. This kind of training is required for all personnel who package or ship specimens. View the program at: or

--Daniel M. Baer, MD

Professor Emeritus

Department of Pathology

Oregon Health and Science University

Portland, OR

Separating red cells for cross match

Q Is it necessary to separate the serum from the red cells in blood banking? What effect would this have on subsequent testing, like cross matching units, if no serum separator is put into the clot tube? I understand the necessity in chemistry but not in blood banking. If serum for blood banking comes from a plain clot tube, will the amount of time the serum sits on the cells affect the blood-bank procedures? We have been told that the clot will absorb antibodies if the serum is not separated.

A Prolonged storage at room temperature can result in bacterial proliferation with hemolysis and a tendency toward polyagglutination, is, therefore, not recommended. In terms of antibody absorption, the red cells in the sample have been bathed in patient plasma while in vivo, and, in general, additional in vitro time spent in association with red cells will not materially affect the concentration of antibodies in the serum.

One exception to this rule would be cold autoantibodies. Their affinity for red cells would be increased with cooling of the tube; and the longer the cold serum sits on the cells, the more absorption of the autoantibody. This is not a bad thing because most of these antibodies are so-called "nuisance" antibodies and are generally not clinically significant. Cold antibodies can cause problems with testing, but the effect would likely not be worse after prolonged storage.

Another exception would be a post-transfusion sample drawn for work-up of a transfusion reaction. Recently transfused cells may not have all antigens fully saturated with antibody, and additional absorption of alloantibody might take place with prolonged storage. This could reduce the concentration of free antibody in the plasma and might affect the antibody screen results. Generally, these samples are processed rapidly because of the need to determine the cause of a transfusion reaction, and prolonged storage is not a common problem. In any event, the absorption of alloantibodies by transfused cells would not have a significant clinical effect since the transfusion reaction work-up of a new positive direct Coombs would generally involve doing an elution, at which time the identify of the antibody would be determined.

--Richard M. Scanlan, MD

Director, Transfusion Medicine

Oregon Health and Science University

Portland, OR

Elevated K when inverting gel tube

Q I have a question about inverting gel tubes. I was trained that the phlebotomist should gently invert a gel tube. A patient recently complained to my lab manager that I had inverted the gel tube after drawing her (this was done after supper). Her K+ level was 5.0. The patient complained the next morning, and the lab manager had someone redraw the patient approximately 12 hours after I had drawn. Her K+ level was then 4.7. The lab manager told me that my draw produced wrong results because I had inverted the tube. I told her I didn't think so and that the instructions on the tube package said to invert the tube five times. She told me that she knew best, that she was the lab manager, and that I was not to invert gel tubes anymore. What do I do?

A This situation has more layers than a Texas onion. We will peel them away one at a time. First, you must follow the manufacturer's recommendations when inverting tubes with additives. This includes clot-activator tubes. Clot activators allow specimens to clot more completely, rendering a cleaner serum specimen after centrifugation. Inverting the tube creates a more homogeneous mixture of blood and clot activator, facilitating complete clotting. If anything, failure to mix a clot-activator tube can result in a falsely higher (not lower) potassium, but only if it is centrifuged before complete clotting has occurred. That is because platelets release potassium as the specimen clots. If clotting continues to occur in the serum after centrifugation of an incompletely clotted specimen, the level of potassium will increase in the separated serum. It is also likely that fibrin strands would develop in the serum, requiring recentrifugation.

I am hard-pressed to believe that a difference in the patient's potassium of 0.3 mEq/L after 12 hours can be logically dismissed as any preanalytical error, much less the proper mixing of a clot-activator tube, as your manager contends. A patient's natural physiology can easily change in terms of its potassium concentration to that degree in 12 hours (diurnal variation). Even if a manager were to blame the variation on a preanalytical error, there are many more plausible specimen-collection variables than the mixing of a clot-activator tube. Some such variables include the length of tourniquet application, pumping of the fist, filling the tubes in an incorrect order of draw, contaminating the specimen with iodine used to cleanse the site, vigorous mixing, inadequate centrifugation, hemolysis, and delayed processing. Mixing the tube is not one of them (unless the mixing was vigorous).

It sounds as if there is more to this disagreement than what is on the surface. You are clearly in the right, but the unasked question is why does your manager insist on exerting her authority in this way? "Because I said so" is fine when the directive has a basis. But judging from the information you provided, there is no basis to the argument that properly mixing the clot-activator tube led to a falsely elevated potassium level. In the interest of getting along, sit down with your manager and tactfully ask what is really driving this conflict. The misapplication of her authority in this regard is a symptom of a larger problem that you need to address.


--Dennis J. Ernst MT(ASCP)


The Center for Phlebotomy Education Inc.

Ramsey, IN

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

Edited by Daniel M. Baer, MD

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:The Center for Phlebotomy Education Inc.; Oregon Health & Science University
Author:Baer, Daniel M.
Publication:Medical Laboratory Observer
Article Type:Interview
Geographic Code:1USA
Date:Nov 1, 2005
Previous Article:Addressing management issues.
Next Article:New CLIAC Chair leads lively agenda.

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