ABSTRACT
OBJECTIVES: An isolated prolongation of activated partial thromboplastin time (aPTT) found in paediatric pre-operative screening could be due to bleeding or non-bleeding aetiologies. The aim of our study was to evaluate clinical benefits of an additional ActinFS and/or a mixing aPTT study to identify a bleeding-related factor deficiency (BRFD). METHODS: Over a 4-yr period, isolated prolongation of aPTT with PlatelinLS was detected in 308 paediatric patients and confirmed in 161 cases by a 2nd sample. ActinFS, a mixing study, FVIII, FIX, FXI, FXII and lupus anticoagulant (LA) were performed. Three different aPTT ratios between PlatelinLS and ActinFS were analysed. RESULTS: We found 17 BRFD, 31 FXII deficiencies and 64 positive LA. A prolonged ActinFS had a significant association with BRFD (P < 0.0001) while a corrected mixing study did not. The direct aPTT ratio had a significant relationship with positive LA (P < 0.05), and with BRFD (P < 0.0001). Using this ratio, the sensitivity of BRFD's and LA's detection could be increased, respectively, to 82% from 59% using ActinFS alone, and to 86% from 55% using mixing study. CONCLUSIONS: Applying this direct aPTT ratio allows to quickly and reliably identify both BRFD and LA sequential to an isolated prolongation of aPTT.
Subject(s)
Blood Coagulation Tests , Blood Coagulation , Coagulation Protein Disorders/diagnosis , Lupus Coagulation Inhibitor/blood , Partial Thromboplastin Time , Preoperative Care , Adolescent , Child , Child, Preschool , Coagulation Protein Disorders/surgery , Female , Humans , Infant , Infant, Newborn , Male , Preoperative Care/methods , Reproducibility of Results , Sensitivity and SpecificityABSTRACT
The diagnosis of lupus anticoagulant (LA) becomes difficult when there is a weak titer of LA antibodies. This study demonstrates that 20 minutes' incubation increases the sensitivity of the mixing test to diagnose LA by 23% and to suspect the antibodies by 66%.
