Specimen Management

Acceptable Coagulation Test Specimens

From Lauren Ball: Do you suggest that most labs use a 4 hour rule for specimen acceptability? We offer PT, PTT, fibrinogen, D-dimer, and anti-Xa tests. PTTs and Anti-Xa tests may need to be performed within 2 hours but the manufacturer’s guidelines suggest that a specimen is good for up to 8 hours for tests […]

Specimen Management

Platelet Counts from Citrate Tubes

Here is some correspondence between Estelle Ninnemann at ACL Laboratories, and Dennis Ernst, at the Center for Phlebotomy Education, Inc. From Estelle, “In our laboratory, phlebotomists collect sodium citrate (blue top) tubes when a patient is known to have a history of platelet clumping. The sample is collected and sent with the lavender top tube […]

Specimen Management

Heparin and Cell-free DNA

Here’s a challenging question from the ASCLS Consumer web forum: “I’m currently on 40 mg of Lovenox daily during my pregnancy. Can that alter the cell-free DNA test in any way? I take my meds at 10 every morning, should i take the blood test after my shot is due? I’m getting different answers from […]

Anticoagulant Therapy

Whole Blood PTTs

From Kirk Guyer, Cascade Technologies: There are whole blood PTT (APTT) assays and there are citrated platelet poor plasma (PPP) PTT assays. What happens in a PPP PTT assay if there are platelets present? Does the PTT result shorten? Can platelets shorten the PTT result in a whole blood PTT assay? I ran a PTT […]

Bleeding Disorders

Bangor Presentations

George was in beautiful Bangor, Maine, Monday, September 12, where he provided two presentations for regional medical laboratory scientists, sponsored in part by Dahl-Chase Diagnostic Services. Handouts for George’s talks are provided below. Please click or tap if you would like to have the handouts. Measuring the DOACs, Whatever Happened to the PT and PTT? […]

Anticoagulant Therapy

New Quick Question: Hemolysis

Please check out and answer our new Quick Question, “How do you manage hemostasis specimens with visible hemolysis?”

Quick Question Archive

Specimens with Hematocrit >55%

From Michelle Fahs, MT (ASCP), Clinical Laboratory Educator, Mercy Hospital St. Louis School of CLS. George, Do you have any recommendations on how the sample should be collected for coag testing if the patient’s hematocrit is >55%? We have in our policy the formula and procedure for adjusting the amount of anticoagulant in the tube […]

Specimen Management

Platelet Clumps on Blood Film

Susan Lemire asks, “Hi, what are most people doing when platelet clumps are found on the blood smear, but the platelet count is within normal range?” Hi, Susan, my hunch is that since we don’t review blood films when the CBC is within acceptable parameters, we probably miss some platelet clumping. CBC profiling instruments do […]

Platelet Function Testing

Clotted Knee Fluid Cell Counts

From Susan Lemire: We received a solidly clotted knee fluid, with minimal non clotted blood. How do others handle these as far as reporting cell count and differential? From George: I’m not certain this approach would resolve your situation, but we treat synovial fluid with hyaluronidase to liquify the clot-forming hyaluronic acid before counting. I […]

Specimen Management

Fibrinogen Storage Stability

From Susan Lemire, can you confirm that the specimen stability for measuring fibrinogen is 24 hours? Thanks. Hi, Susan, the attached Scientific Reports article (a Nature publication) gives specimen stability for several coagulation factors and assay results. The study seems conclusive, as the authors used a sufficient sample of 72 specimens and referenced several additional […]

Specimen Management

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George Fritsma is a medical laboratory scientist, educator, and author. George is a member of the International Society on Thrombosis and Hemostasis, the International Society for Laboratory Hematology, and the American Society for Clinical Laboratory Science.

Cheat Sheets from George

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