Clot Retraction

I thought the clot retraction test had disappeared when the earth cooled, but I heard from Maggie Schneider MT (ASCP) and Karri Henderson MT (ASCP) at William Beaumont Hospital in Oakland, MI, who occasionally use it. If an institution as “august” as Beaumont is using the clot retraction test, there must be more folks in North America using it. So I went to the books, specifically one Donna Corriveau and I edited and published in 1988. 
Here is what we wrote: “When normal whole blood is allowed to clot in a glass tube, the clot retracts from the walls after a few hours, leaving clear serum visible around the clot. Clot retraction depends on normal platelet function, intact thrombasthenin (actin), and the presence of magnesium, ATP, and pyruvate kinase. In thrombocytopenia or platelet function disorders, clot retraction is poor or absent. In the past, quantitative clot retraction procedures were devised in graduated centrifuge tubes to test for platelet function. These procedures have been supplanted by aggregometry and measures of platelet release. It is nevertheless important for the technologist to observe the clotting properties of routine blood specimens to detect possible clinical abnormalities of platelets.

I’d add that in addition to aggregometry we now have urinary 11-dehydrothromboxane B2 (UDHTB), the PFA-100, VerifyNow, platelet flow cytometry, and various global assays such as Thromboelastograph and Rotem to monitor platelet function.

I went back to a 1960 textbook by John H. Gerguson ND, UNC. It seems in those days there was some consideration that clot retraction could be related more to fibrinolysis than platelet function, however the short time to retraction favored the function of platelets.

Anyway, I suggested aggregometry and some of the whole blood screening assays as a good substitute for the clot retraction test. it is even difficult these days to find non-siliconized glass tubes that can be used for the assay. However, I’d like to hear from others about the old procedure. Are you using it? Geo.