Introduction: Hereditary macrothrombocytopenias (HM) are a group of infrequent disorders characterized by hereditary giant platelets. Little has been published about the course of these diseases during pregnancy and delivery.
Subjects and methods: Forty consecutive thrombocytopenic pregnant women were studied. Platelet count, mean platelet volume and blood smear examination were performed. Platelet antibodies were studied by immunofluorescence. Familial study, bleeding time, ultrastructural platelet examination, a von Willebrand disease screening and aggregation tests were carried out when HM was suspected.
Results: Four cases of HM were diagnosed. Giant platelets were observed in all cases, with the typical ultrastructural pattern. Döhle-like cytoplasmic inclusions in granulocytes were observed in one case. Platelet antibodies were detected in only one case. No prophylactic measures to prevent haemorrhage were adopted, and all patients underwent vaginal deliveries. Haemorrhagic events were absent in both mothers and children.
Conclusions: The prevalence of HM in pregnant trombocytopenic women is higher than assumed. Prophylactic treatment should be avoided in the absence of a history of haemorrhagic complications and obstetrical risk factors.