As described in our article (1), pregnant women with a tendency to bleed will, without question, need to undergo further investigation. In asymptomatic pregnant women with a normal platelet count at the start of their pregnancy (=criteria of gestational thrombocytopenia are met), no indication exists for testing platelet function (Table 1 in our article). Severe hereditary thrombocytopathy is obvious from an early age. Mild thrombocytopathy may become obvious in adulthood only; the patients do not show any tendency to bleed in everyday life ([39] in our article), during the course of pregnancy, and during delivery (not least because of different compensation mechanisms of hemostasis). Thrombocytic bleeding is not treatable by administering von Willebrand factor concentrate.
The VerifyNow testing system was developed and licensed only for the purpose of controlling the effectiveness of different platelet aggregation inhibitors. In patients with a tendency to bleed, von Willebrand- syndrome is much more likely than thrombocytopathy. For this reason, platelet function testing cannot be recommended in gestational thrombocytopenia (no symptoms of bleeding). The responsible physician can obviously decide whether to initiate an investigation for antiplatelet antibodies; the diaplacental transmission and the risk for the child were described in our article (page 797 in our article).
Our article focused on the differential diagnosis of thrombocytopenia. Pregnant women who develop the relevant HPA-antibodies have normal platelet counts (page 797). The phenomenon was mentioned briefly but was not our subject, and neither was the treatment (with side effects) of high-risk pregnancies (recurrent fetal losses, thrombophilia).
The disproportionate increase in VWF activity as a distinguishing feature between HELLP syndrome and thrombotic-thrombocytopenic purpura (TTP) has not been described in the literature and cannot be deduced from registry studies. Inquiries to reference laboratories (Hamburg, Bern) did not confirm this observation. The disproportionate increase in VWF activity can possibly be explained on the basis of the pathomechanism (a lack of von Willebrand factor-cleaving protease), but a clear distinction of the phenomena from one another would remain difficult.
Footnotes
Conflict of interest statement
Dr. Bergmann has served as a paid consultant for Instrumentation Laboratories and has received payment from the Roche and Siemens companies for preparing continuing medical education events.
References
- 1.Bergmann F, Rath W. The differential diagnosis of thrombocytopenia in pregnancy— an interdisciplinary challenge. Dtsch Arztebl Int. 2015;112:795–802. doi: 10.3238/arztebl.2015.0795. [DOI] [PMC free article] [PubMed] [Google Scholar]