Objective:  The aim of this study was to investigate the potential role of ADAMTS13 analysis in the early recognition and management of thrombotic thrombocytopenic purpura (TTP) in pregnant women.
Methods:  Five cases of TTP were evaluated retrospectively. Clinical and laboratory findings, von Willebrand factor (vWF)‐cleaving metalloprotease (ADAMTS13) activity and maternal and neonatal outcome were recorded and analysed.
Results:  Five cases were all nulliparous. ADAMTS13 assay was performed and the enzyme activity was less than 5% of the normal controls in three cases. Gene mutation in the 9th exon resulting in amino acid exchange 349Arg→Cys in ADAMTS13 was identified in one patient. After treatment including transfusion of fresh‐frozen plasma (n = 5), packed red blood cells (n = 5), platelet transfusions (n = 2) and/or continued renal replacement therapy (CRRT) (n = 1) and plasma exchange (n = 2), three patients were alive, one died on postpartum day 6 in hospital without plasma exchange and one of familial TTP died three months after discharge.
Conclusion:  With increasing awareness, extra‐attention must be paid to patients with thrombotic microangiopathy and to measurement of ADAMTS13 activity for early diagnosis. Although severe ADAMTS13 deficiency may be helpful for TTP, it may not be sensitive enough to identify all TTP patients. Therefore, despite ADAMTS13 result positive or negative, prompt aggressive management should include early termination of pregnancy, plasma transfusion and/or plasma exchange.