Abstract Number: PB0561
Meeting: ISTH 2020 Congress
Background: Haemolysis is considered one of the major contributors of non-conformities and sample rejection in coagulation testing.
Aims: To investigate effects of haemolysis on methodology and results in a multicentre exercise, and gather information about laboratory approaches to dealing with haemolysed samples.
Methods: In November 2018 UK National External Quality Assessment Scheme for Blood Coagulation ( UK NEQAS BC) conducted an exercise where two different lyophilised plasma samples were distributed to 800 participants comprising of centres registered for prothrombin time (PT), activated partial thromboplastin time (APTT) and either Clauss fibrinogen or thrombin time (TT) in the UK NEQAS BC programme. The same pooled normal plasma was used to prepare 2 samples S18:19 and S18:20. A haemolysate consisting of freeze/thaw red blood cells was added to sample S18:20 in order to create haemolysis at 3g/l concentration. Participants were asked to provide answers to a questionnaire about their laboratory approach to dealing with haemolysed samples including strategies used to deal with different levels of haemolysis.
Results: There was variability in the number of received results for samples S18:19 and S18:20 which depended on the test registered by participants. Results are shown in the table. Variability in practice was observed, out of 501 responses 226 centres indicated they reject haemolysed samples solely on visual checks, with 163 using initial visual checks with further sample rejection evaluation by analyser flags. 333 centres indicated that the level of haemolysis affects sample rejection decisions while 132 stated it does not.
Conclusions: In this exercise, results for performed tests did not show great variability between two samples. This may be explained by artificial construction of the haemolysed sample in this exercise. Variability of responses for dealing with haemolysed samples reflects a lack of clear guidelines in the pre analytical area of sample processing.
| Test | N results | Median ratio S18:19 (range) | Median ratio S18:20 (range) | Median %difference |
| PT | 501 | 1.05 (0.86 – 1.7) | 1.1 (0.85 – 9.23) | 4.8 |
| APTT | 503 | 0.95 ( 0.76 – 1.47) | 0.95 (0.8 – 1.60) | 0 |
| Clauss Fibrinogen | 504 | 2.46 (1.67 – 8.3) | 2.56 (1.62 – 8.0) | 4.1 |
| Thrombin time | 338 | 1.05 (0.67 – 1.37) | 1.01 (0.71 – 1.42) | -3.8 |
[A summary of received results for samples S18:19 and S18:20]
To cite this abstract in AMA style:
Brown L, Jennings I, Kitchen S, Kitchen D, Lowe A, Munroe - Peart S, Walker I. Pre – Analytical Variables in Haemostasis: Results of the UK National External Quality Assessment Scheme for Blood Coagulation Haemolysis Supplementary Exercise [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/pre-analytical-variables-in-haemostasis-results-of-the-uk-national-external-quality-assessment-scheme-for-blood-coagulation-haemolysis-supplementary-exercise/. Accessed September 21, 2023.« Back to ISTH 2020 Congress
ISTH Congress Abstracts - https://abstracts.isth.org/abstract/pre-analytical-variables-in-haemostasis-results-of-the-uk-national-external-quality-assessment-scheme-for-blood-coagulation-haemolysis-supplementary-exercise/