The presence of moderate to severe maternal thrombocytopenia is not likely to has been accurately predict the occurrence of fetal and neonatal alloimmune thrombocytopenia (FNAIT), according to a study published recently in Research and Practice in Thrombosis and Haemostasis.
The study found there was no association with low maternal platelet count or diagnosis of maternal thrombocytopenia in the first or second trimester with the eventual diagnosis of neonatal thrombocytopenia.
Although maternal thrombocytopenia is a common occurrence during pregnancy, the link between maternal and neonatal thrombocytopenia remains to be clarified. The researchers of the current analysis sought to establish the accuracy of maternal platelet counts in the prediction of neonatal platelet counts among pregnant patients with moderate to severe thrombocytopenia.
In addition, they aimed to determine a “best fit” platelet count threshold for neonatal analyses, along with the ways in which a change in platelet threshold that generated an investigation would influence the number of full blood count evaluations that a neonate would ultimately undergo.
Read more about FNAIT prognosis
Approximately 1% of all neonates exhibit thrombocytopenia, with platelet counts of less than 150 x 109/L reported. Even though FNAIT is recognized as being the most common cause of neonatal immune thrombocytopenia (ITP), other immune thrombocytopenias due to maternal antiplatelet antibodies have been reported as well. Currently, no guidance exists on the threshold of maternal thrombocytopenia that should trigger the assessment of a newborn’s platelet count.
In fact, even though 70% to 80% of all cases of thrombocytopenia denote incidental thrombocytopenia of pregnancy or “gestational” thrombocytopenia, a common concern among clinicians who care for the maternal-fetal dyad is that a rarer, but potentially more serious cause, such as ITP, might be to blame for the decline in platelet counts.
Among a total of 550 full blood counts performed, 16 neonates were identified as having thrombocytopenia. Of these 16 newborns, 7 of the mothers had a known diagnosis of ITP. Based on a binomial logistic regression analysis, a limited association was observed between the lowest maternal platelet count and the trimester of onset of maternal thrombocytopenia/development of FNAIT.
According to the receiver operator curve (ROC), a threshold value of 77.5 x 109/L maternal platelets provided the best accuracy for predicting FNAIT.
“In conclusion, a lower maternal platelet threshold for assessing neonates for thrombocytopenia may be more accurate in detecting neonates with moderate-severe thrombocytopenia,” the authors emphasized. “This represents a parsimonious [economical] tool to reduce both clinical and laboratory burden of testing[,] as well as avoid unnecessary painful phlebotomy in healthy neonates,” they concluded.
