Successful treatment by double filtrate plasmapheresis in a pregnant woman with the rare P blood group and a history of multiple early miscarriages.

Individuals of P type, a rare blood group, have anti-PP(1)P(k) antibody in their serum, which causes spontaneous abortion in the early stages. We report a patient of p type suffering from multiple spontaneous abortions. We also review previously reported cases from published work. A 36-year-old woman (gravida 2, para 0) was referred to our hospital because of habitual abortion. At the third pregnancy, we started double filtration plasmapheresis (DFPP) from 7 weeks 3 days to remove the antibody. We attained rapid decline in the titer and normal fetal growth. Gradual tapering of the DFPP frequency caused neither a rebound of the titer nor growth retardation. During the course, she experienced only one episode of catheter infection as an adverse effect. At 37 weeks 3 days, after 57 DFPP repetitions, a 2496 g girl was delivered by cesarean section. The infant suffered neither from anemia nor from severe jaundice. A review of previous reports indicates that the titer of the pathogenic antibody should be kept as low as possible from the early gestational stage in P-incompatible habitual abortion cases, otherwise the case typically comes to an unfavorable outcome. Plasma exchanges with fresh plasma potentially induce contamination by either known or unknown pathogens. Such risks are reduced using DFPP because the volume of albumin solution that replaces fresh plasma is less than that by plasma exchange. The present case, along with previous reports, shows that DFPP is an effective therapy for treating P-incompatible pregnancy.