Answering your questions on blood banking and CLIA, xanthochromia and von Willebrand profiles.

Q Our blood bank furnishes red cells and components for transfusion to outpatients and home health patients. We require pre-transfusion blood work (H&H and platelet count) be done in our hospital lab before transfusion. Several of our staff physicians (primarily oncologists) believe since their offices are CLIA-approved, we should accept their lab values. In the past two years, however, we've prevented at least two unnecessary platelet transfusions and five or six unnecessary transfusions of packed RBCs thanks to our pre-transfusion policy.

We feel since our lab director ultimately is responsible for the patient if adverse reactions occur, we should have documented results of pre-transfusion tests. Furthermore, we believe inserting clinicians' lab results into patient hospital records (our hospital does not have a separate outpatient record-keeping system) creates a separate set of problems.

We've learned, however, none of the blood bank supervisors of four area hospitals requires pre-transfusion testing be done in their labs. In fact, most do not require lab documentation noting the need for transfusion before releasing blood products. Are we being unreasonable?

A This question brings out the controversial issue of how much a laboratory can and should rely on another lab's data. A major consideration should be the type of CLIA approval your physicians' laboratories have. Waived labs should not be performing H&H or platelet counts. Moderate complexity laboratories, on the other hand, may perform automated counts.

You certainly are within your rights to ask what certificate your staff physicians hold.

Out of curiosity, I put this question on the AABB OnLine bulletin board. Two respondents said yes, they would accept clinicians' results. (None said no.)

I was reminded by one respondent that AABB Standard A2.500 states tests required by AABB standards not performed by the blood bank or transfusion service must be performed in a laboratory accredited by the AABB, CAP, JCAHO, HCFA, or registered by FDA. Using this as a guideline, these tests could be accepted and used as an indication for transfusion.

On the other hand, you list several cases where your staff physicians' results were wrong. Their QC must not be up to par. Have you documented this? Is one particular laboratory to blame? If so, notify the facility immediately.

Apparently, most of your area laboratories feel this practice is acceptable, as do several of my colleagues and bulletin board members. Personally, however, I would not accept results from physicians' offices without confirming them in my own lab (I'm sure I'll take some heat for saying this). If a patient is transfused in your hospital and has adverse effects, one of the first questions your lab will be asked is, "What were the indications for transfusion?" Quoting another lab's results will be embarrassing.

Perhaps I also feel this way because I live in California, where lawsuits are a way of life. I can hear the lawyers already: "You mean to tell me you subjected my client to a life-threatening procedure and relied on another laboratory for those results that indicated a transfusion was needed? How much would it have cost you to repeat the values?" The answer easily could be painful.

Remind your pathologist that hospitals and pathologists can be held liable for transfusion problems. I recommend you devise a policy and run it by the hospital executive committee for approval.

I realize under the "new look" in medicine the goal is to eliminate redundancy (meaning, let's do it cheaper). But accepting someone else's results as an indication for performing a serious procedure seems to be going too far.

Having said all this, if the blood is being issued to the physicians for office or home transfusion only, then I would agree with the majority. Incidentally, indications for transfusion of platelets, fresh frozen plasma, and red cells were published as consensus reports in JAMA between 1985 and 1987 and subsequently distributed as a report by the National Institute of Health. A relatively current guideline for platelet transfusions also was published in Transfusion Medicine, Vol. 2, 1992, 311-318.

- Byron A. Myhre

Xanthochromia

There has been much discussion at our facility about the correct way to report xanthochromia in cerebrospinal fluid (CSF). We agree xanthochromia is determined on the supernatant of centrifuged CSF. The problem is some of us report xanthochromia as any color from faint straw to bright yellow. The rest of us say xanthochromia should be reserved for use in association with subarachnoid bleeding and is caused by the release of hemoglobin from hemolyzed red blood cells. The color will range from pale pink to orange to yellow, depending on the lapse of time after hemorrhage. Can you help clear up this confusion?

A The definition of xanthochromia of CSF based on its appearance, written by Krieg,[1] has endured over many editions of Clinical Diagnosis and Management by Laboratory Methods. The centrifuged CSF should be crystal clear and without color when compared to a tube of water. Xanthochromia is defined by a faint pink, orange, or yellow color.

This definition does not indicate the cause of the color. Krieg lists many causes, including red cell lysis, either due to spontaneous bleeding or lysis of red cells due to a delay in examining CSF containing red cells from a traumatic tap. Other causes include bilirubin from lysed red cells or bilirubinemia, increased CSF protein, carotenoids, melanin, and contamination by a skin disinfectant. He notes that red cell lysis, either from a subarachnoid bleed or traumatic tap, can begin within one hour and that prompt examination of the CSF is necessary. Although visual examination of the CSF usually is the basis for a xanthochromia diagnosis, spectrophotometric methods have been described.

A traumatic tap is detected frequently by clearing the later tubes when several tubes are collected and by clotting the CSF when it is very bloody. Since xanthochromia can result from lysis of the cells in a traumatic tap after one hour, rapid processing and examination are important.

Subarachnoid hemorrhage is a cause for xanthochromia. But remember, it is the appearance of the CSF, not the etiology of the change, that defines this condition.

- Daniel M. Baer

Reference

1. Krieg AF, Kjeldsberg CR. Cerebrospinal fluid and other body fluids. In: Henry JB, ed. Clinical Diagnosis and Management by Laboratory Methods. 18th ed. Philadelphia, Pa: W.B. Saunders; 1991.

Von Willebrand profile

Q What tests can be done to define von Willebrand's disease? Are multiple tests better than merely ordering the von Willebrand Factor assay?

A Von Willebrand's disease (vWD) is the most common congenital bleeding disorder. There are at least six different forms: I, IIA, IIB, III, hemophilia-type, and platelet-type. These variants are differentiated on the basis of a panel of lab tests that include the bleeding time, platelet count, partial thromboplastin time, yon Willebrand factor (vWF) activity and antigen, factor VIII levels, ristocetin cofactor, and vWF multimeric composition. Depending on the vWD type, these tests may yield normal or abnormal results.

So if only a yon Willebrand factor assay was ordered, it would be abnormal in Type I vWD but might be normal or abnormal in all other cases. Similar problems could occur for most of the other tests in the panel given above. For this reason, the full panel of tests usually is necessary. Brandt provides a nice summary of these findings.[1]

The differentiation of the various types of vWD is of more than academic interest since transfusion therapy (including DDAVP), if needed, may differ depending on the vWD type. In such situations, therefore, a definitive diagnosis is necessary.

One final comment: A recent article on the laboratory diagnosis of vWD indicates some potential pitfalls dependent on the type of specimen received in the laboratory.[2] These authors point out the need to know the true nature of the plasma specimen received and tested in the coagulation lab. Neither filtered plasma nor serum are appropriate specimens for vWF assay since falsely low assays may occur if improper specimens are tested.

- John A. Koepke

References

1. Brandt JT. Laboratory evaluation of platelet disorders. In: McClatchey KD, ed. Clinical Laboratory Diagnosis. Baltimore, Md: Williams and Wilkins; 1994.

2. Favaloro EJ, Facey D, Grispo L. Laboratory assessment of von Willebrand factor. Amer J Clin Pathol. 1995; 104: 264-271.