Upload
others
View
0
Download
0
Embed Size (px)
Citation preview
6/17/2013
1
Basic coagulation testing and interpretation
By Dr. Gwen Clarke
…the way coagulation works
http://www.revespcardiol.org/en/the-new-coagulation-cascade-and/articulo/13114167/
6/17/2013
2
…the way we test
http://www.recothrom.com/about-recothrom.html
What can we test (easily)
• PTT
• PT (INR)
• Fibrinogen
• Thrombin Time
• Platelet count (and morphology)
6/17/2013
3
…the way we test
http://www.recothrom.com/about-recothrom.html
What do abnormal results mean?
That depends…Clinical History
Medications
Which tests are abnormal
How abnormal are they
Is this finding long standing or new
Factor deficiency, or coagulation inhibitor
6/17/2013
4
How can you follow up?
• Repeat if unexpected
• Determine if prolonged due to deficiency or inhibitor… order an inhibitor screen
• Don’t treat a lab abnormality (in the absence of clinical abnormality) at least until you figure out the cause…
PT/PTT inhibitor screen
• Mix patient plasma with a normal pool of plasma.
• Incubate.
• Repeat PT or PTT
6/17/2013
5
http://www.usmle3.com/
Peripheral blood film
• Review platelet morphology and look at additional findings that might impact on clotting or bleeding
6/17/2013
6
Tests for VWD
• Common bleeding disorder
• May contribute to prolonged PTT (or may not)
• If clinical history is suspicious:• VWF, Ristocetin Cofactor and Factor VIII are diagnostic tests
• Bleeding Times are not orderable, and not necessary to make this (or any other) diagnosis
Tests for Lupus anticoagulant
• Prolonged PTT
• Inhibitor screen does NOT correct
• Order • Lupus anticoagulant• Antiphospholipid antibodies
• Assess patient for clinical features of antiphospholipid syndrome and consider hematology consultation