Prothrombin time (PT) and activated partial thromboplastin time (aPTT) are coagulative screening tests used for the diagnosis of several pathologic conditions, such as liver failure, coagulation factor deficiencies, anti-phospholipid antibodies (lupus anticoagulant), and factor VIII inhibitors. A new test was developed several years ago to detect the amount of thrombin generated during plasma clotting, using low tissue factor concentrations and fluorogenic substrates, and it has since been used successfully in conditions ranging from hypocoagulable to hypercoagulable states. However, the test is expensive and difficult to perform in nonspecialized laboratories, and efforts have thus been made to find an economic and easily implementable test suitable for routine use, even in nonspecialist laboratories.


To evaluate clot waveform analysis (CWA) of PT and aPTT, aiming to show the dynamics of clot formation; that is, the “hidden” features of both tests. CWA can be implemented by using an automated coagulometer with dedicated software. The aim of this review was to evaluate whether CWA is able to detect both hypercoagulative and hypocoagulative states.

Data Sources.—

Using MedLine, we searched and retrieved articles relating to CWA. We only considered articles published in English, but with no limits in terms of article type, publication year, or geography.


CWA was shown to be a reliable test in patients with both hypercoagulable and hypocoagulable states. It represents a simple and inexpensive global test that can easily provide information on the behavior of the coagulation system. Both the first and second derivatives are computed by using dedicated software implemented with an on-board algorithm in a routine automated coagulometer.

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Author notes

The authors have no relevant financial interest in the products or companies described in this article.