Laboratory tests requested on a patient scheduled for early morning surgery include a CBC with platelet count. An automated platelet count is 57 x 10^9/L. In the monolayer area of the peripheral blood smear, there are approximately 12 platelets per oil immersion field, many encircling neutrophils. Controls are in range. Based on this information, the best course of action is

Laboratory tests requested on a patient scheduled for early morning surgery include a CBC with platelet count. An automated platelet count is 57 x 10^9/L. In the monolayer area of the peripheral blood smear, there are approximately 12 platelets per oil immersion field, many encircling neutrophils. Controls are in range. Based on this information, the best course of action is

• A. Report all the results because the instrument is functioning properly
• B. Alert the physician immediately so cancellation of surgery can be considered
• C. Thoroughly mix specimen and repeat platelet count; if results remain the same, report all results and indicate that platelet count has been confirmed by repeat testing
• D. Have the specimen redrawn using 3.2% sodium citrate as the anticoagulant

Answer: (D)

The key idea is that the very low automated platelet count is most likely an artifact caused by the blood collection method, not true thrombocytopenia. The smear shows platelets clumping around neutrophils, which is a classic sign of EDTA-induced platelet aggregation. When platelets clump in the EDTA tube, the analyzer records fewer platelets than are actually present, so the control results being normal doesn’t reflect a real drop in platelets. Redrawing the specimen in a different anticoagulant, specifically 3.2% sodium citrate, is the best next step because citrate prevents that EDTA-induced clumping and gives a more accurate platelet count. If the citrate result comes back normal (after correcting for dilution), true thrombocytopenia can be ruled out and surgery planning can proceed with confidence. If the citrate count remains low, true thrombocytopenia would need further evaluation. Repeating the same EDTA sample would not resolve the issue since the clumping artifact persists, and it wouldn’t provide an accurate assessment for surgical planning.

The key idea is that the very low automated platelet count is most likely an artifact caused by the blood collection method, not true thrombocytopenia. The smear shows platelets clumping around neutrophils, which is a classic sign of EDTA-induced platelet aggregation. When platelets clump in the EDTA tube, the analyzer records fewer platelets than are actually present, so the control results being normal doesn’t reflect a real drop in platelets.

Redrawing the specimen in a different anticoagulant, specifically 3.2% sodium citrate, is the best next step because citrate prevents that EDTA-induced clumping and gives a more accurate platelet count. If the citrate result comes back normal (after correcting for dilution), true thrombocytopenia can be ruled out and surgery planning can proceed with confidence. If the citrate count remains low, true thrombocytopenia would need further evaluation.

Repeating the same EDTA sample would not resolve the issue since the clumping artifact persists, and it wouldn’t provide an accurate assessment for surgical planning.