The study's objective was to identify HPA 1a-negative women and to offer them an intervention program aimed to reduce morbidity and mortality of neonatal alloimmune thrombocytopenia (NAIT). HPA 1 typing was performed in 100 448 pregnant women. The HPA 1a-negative women were screened for anti-HPA 1a. In immunized women, delivery was performed by Cesarean section 2 to 4 weeks prior to term, with platelets from HPA 1a-negative donors reserved for immediate transfusion if petechiae were present and/or if platelet count was less than 35 ؋ 10 9 /L. Of the women screened, 2.1% were HPA 1a negative, and anti-HPA 1a was detected in 10.6% of these. One hundred seventy pregnancies were managed according to the intervention program, resulting in 161 HPA 1a-positive children. Of these, 55 had severe thrombocytopenia (< 50 ؋ 10 9 /L), including 2 with intracranial hemorrhage (ICH). One woman with a twin pregnancy missed the follow-up and had one stillborn and one severely thrombocytope-

This method is not suitable for routine analysis because of the lack of a positive control for RHD-negative female fetuses and a decrease in PCR sensitivity when performing duplex PCR. Fetal DNA in maternal plasma is better preserved when the blood sample is kept cool.

Background: Neonatal alloimmune thrombocytopenia (NAIT) is most frequently caused by antibodies against the human platelet antigen (HPA) 1a. The objective of the present study was to identify HPA 1a negative women, and to offer them an intervention program aimed to reduce morbidity and mortality of NAIT. Methods: A total of 100,448 pregnant women were HPA 1 typed. The HPA 1a negative women were screened for anti-HPA 1a, which was quantified when present. Immunized women were referred to a university hospital for clinical follow-up, including ultrasonographic examination of the fetal brain. Caesarean section was performed 2–4 weeks prior to term with platelets from HPA 1bb donors reserved for immediate transfusion if petechiae were present and/or if platelet count was &lt; 35 × 109/L. Results: Of all women typed 2.1% were HPA 1a negative. Anti-HPA 1a was detected in 210 of 1,990 HPA 1a negative women. A total of 170 pregnancies in 154 HPA 1a negative women were managed according to the intervention program. These women gave birth to 161 HPA 1a positive children of whom 55 had severe thrombocytopenia (&lt;50 × 109/L) including two with ICH. There were no intrauterine deaths. In 13 previously published prospective studies comprising 131,465 women of whom 2,290 were HPA 1a negative, there were 10 cases with severe NAIT-related complications (3 intrauterine deaths and 7 neonates with ICH), which are significantly higher than in our study (p &lt; 0.05). Conclusions: The screening and intervention program seems to reduce mortality and serious morbidity associated with NAIT.

Alloimmunization is a common phenomenon after transfusion, with an estimated incidence of 0.5% increasing to 20-60% in chronically transfused patients. In recently transfused patients, serological typing can be hampered by mixed field agglutination. We established RT-PCR methods for RHD, RHC/c and RHE/e typing using mRNA from reticulocytes. Molecular typing was performed soon after 51 separate mismatched transfusion events involving 30 patients. Accurate identification of the transfused patients' phenotype was confirmed in all cases. Reticulocyte maturation studies revealed that temperature is a crucial parameter for transition into mature red blood cells.