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1.1 This test method covers the screening of circulating blood-contacting device materials for their ability to induce blood coagulation via the intrinsic coagulation pathway. This assay should be part of the hemocompatibility evaluation for devices and materials contacting human blood, as per ANSI/AAMI/ISO 10993-4. See also Practice F2888.

1.2 All safety policies and practices shall be observed during the performance of this test method.

1.3 All plasma and any materials that had contact with plasma will be bagged in a biohazard bag, properly labeled with the contents, and disposed of by appropriate means. The plasma should be handled at the Biosafety Level 2 (BSL-2) as recommended in the Centers for Disease Control (CDC) National Institutes of Health (NIH) Manual Biosafety in Microbiological and Biomedical Laboratories (BMBL, current edition).

1.4 The normal pooled human plasma must have tested negative for Hepatitis B (HBV) and Human Immunodeficiency (HIV) viruses. The plasmas should be treated like any patient plasma using standard precautions. The plasma should be handled at the BSL-2 as recommended in the CDC/NIH Manual BMBL.

1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

4.1 The purpose of this test method is to determine the time citrated plasma exposed to medical materials takes to form a clot when exposed to a suspension of phospholipid particles and calcium chloride. In this test method, the test article is the activator. The PTT assay is a general screening test for a medical material’s ability to activate the intrinsic coagulation pathway. Material samples that show a shortened PTT are activators of the intrinsic coagulation pathway.

4.2 The test article, reference materials, and controls are exposed to human plasma. The plasma is tested on a coagulation device. Each sample tube is assayed in duplicate. The results are reported as a percentage of the negative control.