Coagulation Specimen Management

Thanks to Tigist Bekalu for these specimen management questions…

• What should we do when there is lipemia, icterus (bilirubin), or hemolysis in coagulation tests? Which tests are affected and which are not?
• How are the results typically reported when we encounter hemolysis, icterus, or lipemia? Sometimes, instead of a number, it just says “Failed.”
• Also, regarding special coagulation tests–are the results affected by room temperature? For example, if the sample is not stored in the freezer, could that impact the accuracy?

Dr. Bekelu, the key reference for coagulation specimen management is the Collection, Transport, and Processing of Blood Specimens for Testing Plasma-Based Coagulation Assays. 6th ed. CLSI guideline H21. Clinical and Laboratory Standards Institute; 2024. We’ve posted a few Fritsma Factor discussions about hemolysis, listed here:

• ED Specimen Hemolysis, 6 Dec 1016
• Quick Question on Specimen Hemolysis, 7 June 2017
• Hemolysis and Heparin Assay, 3 Aug 2017
• Reducing Hemolysis Rate, 1 Feb 2021
• Hemolysis Level and Coag Assays, 18 Nov 2021
• DIC and Hemolysis, 25 July 2023
• Quick Question on Hemolysis, 30 Aug 2023
• Quick Question on Hemolysis, 1 Oct 2023

A second reference, Kitchen S, Adcock DM, Dauer R, et al. International Council for Standardization in Haematology (ICSH) recommendations for processing of blood samples for coagulation testing. Int J Lab Hematol. 2021;43:127283. doi: 10.1111/ijlh.13702. PMID: 34581008 provides insight into efforts to link hemolysis to platelet and coagulation factor activation.

Using both the CLSI and ICSH documents, we acknowledge that medical laboratory scientists have for decades visually inspected supernatant plasma for hemolysis, icterus, and lipemia and have rejected all specimens with visible hemolysis (pink or red plasma) because of concern for confounding platelet and coagulation factor activation. Hemolysis can also influence the results from spectrophotometric coagulometers. So can icterus and lipemia, however these specimens may be referred to measurement using coagulometers that feature electromechanical clot detection when available.

Current instruments offer a spectrophotometric HIL detection “channel,” enabling their manufacturers to establish theoretical decision points below which the specimens provide valid results. Automated HIL detection exceeds visual inspection accuracy and precision, and in theory, our specimen rejection rate becomes smaller. When HIL detection is available, we locally validate the manufacturer pre-sets. Here are some recent Fritsma Factor posts regarding icterus and lipemia:

• Do Icterus and Lipemia Affect the Beckman TOP? 28 Oct 2010
• Anti-Xa and Lipemia, 18 Nov 2010
• Ultracentrifugation for Lipemia, 1 Aug 2011
• Lipemia, Hemolysis, and D-dimer, 8 July 2012
• Lipemia Statistics, 6 Feb 2016

While most hemolysis is the result of variant in vitro specimen management, some hemolysis may be intravascular, related to microangiopathic hemolytic anemia or certain treatments. Rather than rejecting hemolyzed specimens, the lab staff communicates with the patient’s provider to learn if a hemolytic condition is present. If so, we process the specimen and append a notation to the results. In all cases of specimen rejection, the laboratory staff explains and requests a new specimen.

Specimen storage: again using the CLSI and ICSH recommendations, coagulation specimens for PTs may stand capped at between 18–25°C (ambient or “room” temperature) for up to 24 hours before testing. Specimens that contain heparin must be centrifuged to produce platelet-poor plasma within 1 hour of collection and tested or frozen at ≤ –30°C until ready for testing. When ready, they should be thawed rapidly in a water bath or dry incubator, mixed, and tested immediately. All specimens destined for specialty testing use this approach.

Again, thank you for your question, and please feel free to follow up as necessary.