The Perosphere ClotChek™ system consists of a hand-held, battery-operated blood coagulation instrument and disposable test cuvettes for use at the point-of-care (POC). The instrument performs a whole blood clotting time (WBCT) test using freshly drawn, non-citrated whole blood. The purpose of the present study is to characterize the performance of the Perosphere ClotChek™ as a quantitative measurement of the WBCT in patients taking one of the following Direct Oral Anticoagulants (DOACs), rivaroxaban or apixaban.

Inclusion Criteria:

• Be informed of the nature of the study and provide written informed consent before any study-specific procedures are performed.
• Be 18- to 80-years-of-age, inclusive, at time of consent.
• Have suitable venous access for at least a single venipuncture.
• Eligible patients on anticoagulants must have taken their prescribed anticoagulant regularly at least for one month prior to study participation for inclusion
• Eligible patients on anticoagulants must have been on their anticoagulant therapy for at least one month.

Exclusion Criteria:

• Have a personal or family history of clotting disorder or hematologic abnormality, such as excessive bleeding, joint hematoma, thrombovascular disease, thrombocytopenia, or any chronic condition requiring treatment with transfusions, other than the condition for which a DOAC was prescribed.
• Have a history of unexplained syncope.
• Have a history within six months prior to Screening of peptic ulcer or gastrointestinal bleeding (including hematemesis, melena, or rectal bleeding).
• Consume more than five cigarettes per day.
• If female, have a history of excessive or dysfunctional uterine bleeding (unless the subject had a subsequent hysterectomy).
• If female, be pregnant, breastfeeding, or planning to become pregnant during the study.

Patients on rivaroxaban or apixaban between the ages of 18 and 80 years old.