Getting rid of bleeding times.

Q We are a medium-size (275-bed) community hospital, specializing in joint-replacement surgery and rehab. We also have a very active obstetrics (OB) department. We still have doctors who insist on ordering bleeding times, even though my director has told them it does not have much value, especially in predicting surgical bleeding. As the coagulation supervisor, I would like to replace it with the PFA-100 (platelet function analyzer). My director is on board but not my manager (who does the budget and has to justify any equipment purchases). We do not do very many (70 per year) but, to me, even one is too many, especially when you have an instrument like the PFA-100 on the market. So, my problems are 1) how do I justify this instrument, and 2) how do I do a validation and/or correlation for the instrument? I have asked the two main oncology groups to help by sending me patients for testing; but, so far, no one has come. Is validation and correlation necessary in this case?

A We are a medium-size pediatric hospital with 200 beds currently and will expand to 250 beds soon. We have managed to decrease the orders of the bleeding time test gradually and, eventually, eliminated it. During the past two years when a bleeding time was ordered, a pathologist contacted the ordering physician and convinced him that PFA-100 was better than bleeding time. We have not encountered any resistance since we started calling physicians. Most of the time, physicians did not know the existence of PFA-100. As time went by, we raised the awareness of physicians for using PFA-100 instead of bleeding time. We also found the orders of bleeding time decreased significantly during the past two years. Finally, we completely eliminated the test a few months ago.

In our institution, hematologists are routinely using PFA-100 to evaluate patients with bleeding tendencies. We used to send our tests to a nearby university medical center; however, we often encountered the situation that collected blood samples were clotted when they arrived in the outside laboratory. It is very awkward and devastating to redraw a blood sample from a child. Hematologists are the advocate for performing PFA-100 in-house. Our justifications are the quality of patient care and the satisfaction of physicians and families.

Validation Procedure

Validation:

1. Precision

2. Correlation: duplicate samples tested in our lab and university medical-center laboratory

Sample sources:

1. Samples with normal value: normal volunteers in the lab

2. Samples with abnormal values

a. Normal volunteers in the lab who took aspirin (prolonged EPI but normal ADP)

b. Collected blood samples from normal volunteers mixed with Tirofiban* in vitro (prolonged both ADP and EPI)

*Tirofiban is a non-peptide inhibitor of the platelet glycoprotein IIb/IIIa receptor, the final common pathway for platelet aggregation. Tirofiban is a safe and effective agent in combination with heparin and aspirin in the setting of an acute coronary syndrome.

--Min Xu, MD, PhD

Clinical Pathologist

Department of Laboratories

Children's Hospital and Regional Medical Center

Seattle, WA

Edited by Daniel M. Baer, MD

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 [e-mail].