Hematocrit interference in coagulation tests: what else can we do?

AUTORI

ABSTRACT

Hematocrit interference in coagulation tests: what else can we do?

The required blood to anti-coagulant ratio in the tubes for coagulation tests, is 9:1; any deviation from this ratio should be avoided as it may lead to erroneous analytical results. One of the variables influencing the ratio is an elevated hematocrit (>55%), because the elevated concentration of citrate in the plasma specimen can cause clotting times falsely increased. These erroneous results can lead to possible misdiagnosis, incorrect patient treatment and/or the performance of additional unnecessary investigations. We present the case of a 46-year-old man referred to the laboratory for a pre-surgery check. The presence of elevated values in his coagulation tests led to delayed surgery and to additional tests. Once the error was detected, a root cause analysis was performed. The main contributing factors to the pre-analytical error were identified using Ishikawa method; factors related to the organization, staff and environment were identified and analyzed. Preventive actions (safety barriers) were designed to prevent the error from recurring. The safety barriers implemented were: an automatic flag displayed in the information laboratory system (LIS) in cases of elevated hematocrit (>55%), to enhancement of the possible error detection plus additional laboratory staff training. At the best of our knowledge, since these safety barriers were applied three years ago, no coagulation test results interfered by high hematocrit have been released from our laboratory. This case demonstrates the importance of implementing safety barriers to prevent errors arising from situations that, although already described and well known, may go unnoticed by the laboratory staff

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