Relationship between Circulating Platelet Counts and Ductus Arteriosus Patency after Indomethacin Treatment

Objective To determine whether low platelet counts are related to the incidence of patent ductus arteriosus (PDA) after indomethacin treatment in preterm human infants. Study design Multivariable logistic regression modeling was used for a cohort of 497 infants, who received indomethacin (within 15 hours of birth). Results Platelet counts were not related to the incidence of permanent closure after indomethacin constriction. There was a relationship between platelet counts and the initial degree of constriction; however, this relationship appeared to be primarily influenced by the high end of the platelet distribution curve. PDA incidence was similar in infants with platelet counts 9 /L and those with platelet counts above this range. Only when platelet counts were consistently >230 ×10 9 /L was there a decrease in PDA incidence. Conclusion In contrast to the evidence in mice, low circulating platelet counts do not affect permanent ductus closure (or ductus reopening) in human preterm infants.