I received this question on September 15 from Carolina Vilchez:
I am Carolina Vilchez, an Adjunct Professor at Rutgers-SHP, and a Clinical Educator at The Valley Hospital in Ridgewood, NJ. I was wondering if you would kindly answer a few questions about coagulation blood sample collection and management.
We have been having some issues in the laboratory with seasoned staff as well as new staff members and debates about QNS samples for routine coagulation tests. Certain staff members will run slightly underfilled samples for routine coagulation tests, while newer staff members cancel those samples as QNS and request new draws.
We follow CLSI guidelines and other resources to create our policies. Currently, our policies state that citrated blood specimens for coagulation should be rejected if they are underfilled (under the minimum fill line), which we assume is 90%. According to the International Council for Standardization in Hematology (ICSH) recommendations for the collection of blood samples for coagulation testing, blood with <80% of nominal filling volume should be rejected by the laboratory and should NOT be analyzed. Do you suggest that we continue to enforce the <90% rejection rule or is it advisable to use the 80-90% rule in an effort to avoid over-canceling samples and requesting new draws?
We are also finding out that the personnel are evaluating a sample for sufficient quantity only after the specimen was spun down in the centrifuge. I was under the impression that this incorrect practice and that samples should be evaluated for quantity before they are placed in the centrifuge.
I appreciate you taking the time to read my questions. Any advice that you can provide on this would be greatly appreciated.
With Kind Regards,
Carolina Vilchez, MS, MLS (ASCP)H
Adjunct Assistant Professor
Medical Laboratory Science Program
After consulting with expert Bob Gosselin, I replied…
- Your “instructions for use” [IFU] should be based on the manufacturer’s specifications. I recall that BD establishes anything less than 90% as a short draw.
- It’s off-label, but since short draws raise the AC/blood volume ratio, potentially prolonging PTs and PTTs, we think a normal “routine” PT or PTT on a short draw is reportable.
- Whether the specimen volume is estimated pre- or post-centrifugation is moot.
Please post your comments below, we’d like to confirm that we are giving the best advice.