Blast Flag

An indicator that appears on the hard copy of an automated hematology analyzer—e.g., Coulter’s STKS—that signals the possible presence of blast cells when the device is performing an automated WBC differential. Blast flags usually indicate the presence of acute—myeloid or lymphoblastic—leukaemia, and require a manual differential by a technologists by microscopy
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Still, no cases with blasts were missed by the optimized criteria, although the blast flag was only detected in 11 of 12 cases.
33%) were triggered by atypical lymphocyte flags, and 9 of 12 (75%) were triggered by blast flags (abnormal lymphocytes/ lymphoblast flags).
For example, instruments that use light scatter and fluorescence will flag samples that contain cell populations in certain areas of their scatter-grams with a blast flag.
Optimization began by raising the cutoff of each flag from the factory default setting in increments of 10 units and calculating the YI of each level for the identification of the specific abnormality denoted by the flag (eg, the blast flag for blasts).
4% (PPV of the blast flag for the presence of blasts) and 33% (PPV of the immature granulocyte flag for the presence of myelocytes and/or metamyelocytes) (Table 2).
All 14 cases were detected by our optimized criteria; 12 (86%) by the blast flag and 2 (14%) by a combination of the other 4 user-adjustable flags.
No cases of blasts would have been missed using optimized criteria, although the optimized blast flag only detected 12 of the 14 cases.
The last missed case would only have been detected by decreasing the blast flag to 110.
Number of False-Positive Samples and the Positive Predictive Values (PPVs) of Each Flag for Its Specific Abnormal Finding (Optimization Set, n = 502) Immature Category Blast Flag Granulocyte Flag Factory-set thresholds False-positives, No.
Combined evaluation of the Blast flag with the Abn Lympho/L_Blasts flag on the XE-2100 did not increase the sensitivity of blast cell flagging but resulted in an increase of FP results.