Thrombocytopenia in neonatal infection.

Serial platelet counts by phase microscopy were done for three groups of neonates who were admitted to the Special Care Unit of the Miller Children's Hospital, Group 1 (78 neonates) was evaluated for septicemia. Group 2 (28 neonates) was randomly selected sick neonates whose working diagnosis was not septicemia. Group 3 (16 neonates) was clinically normal preterm neonates (28 to 36 weeks gestation). For group 1 and 2, platelet counts were done serially, at the time blood and cerebrospinal fluid cultures were obtained and then 12, 24, 48 and 72 hours later. For group 3, plasma counts were done on the second, seventh, fourteenth, twenty-first, and twenty-eighth day of life. Sixteen of the group 1 infants were found to have septicemia; ten of these 16 had thrombocytopenia (platelets less than 100,000/mm3). In group 2, five infants had thrombocytopenia, one because of isoimmune disease and four as a result of possible disseminated intravascular coagulation. Thrombocytopenia persisted for 1 to 10 days; platelet counts of group 3 were the same as those of older children and adults.