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Objective To study and monitor the situation of femomaternal hemorrhage (FMH) in RhD-negative pregnant women in Tianjin, obtain the FMH data of such population, and analyze the relationship between FMH and age, blood type, gestational age, hemolytic disease of postpartum neonates, etc. Methods The FMH level was detected by flow cytometry with FITC-anti-HbF monoclonal antibody. The blood type was detected by blood serum method. The irregular antibody was identified by saline method and indirect anti-human ball method. The hemolysis of postpartum neonates was detected by three tests of hemolysis. Results The FMH volume of 86 RhD negative pregnant women was between 0 and 11.48 ml, with an average of 1.82 ml. There were 63.95％of pregnant women showed a volume of FMH<2.0 ml, 23.26％between 2 and 4 ml, 11.63％between 4.0 and 10.0 ml, and 1.16％>10 ml. The proportion of lower FMH in pregnant women≤30 years old was>11.71％higher than that in the pregnant women>30 years old, but the difference was no statistical significant. There was no significant difference in FMH of pregnant women with O, A, B and AB types. The proportion of higher FMH in pregnant women with compatible ABO blood type with her husband was 12.46％ lower than that of the heterozygous cases, but the difference was no statistical significant. The proportion of higher FMH in the pregnant women with 28 to 32 weeks gestational age was 14.55％ higher than that of ≤28 weeks and was 35.32％ higher than that of >32 weeks, and the differences were statistical significant. Three samples in the 86 samples were positive for anti-D antibody, and their three hemolytic test results were strongly positive with the anti-D titer from 1:2 to 1:32 and the FMH volume from 1.50 to 6.93 ml. The proportion of lower FMH in the 10 pregnant women without postpartum hemolysis was 70％ higher than that in 5 pregnant women with postpartum hemolysis, but the differences were not statistical significant. Conclusions The results suggest that monitoring FMH content by flow cytometry can reflect FMH in Rh-negative pregnant women. The studies on the relationship between FMH and age, blood type, pregnant time and hemolytic disease of postpartum neonates can provide basically experimental data for standard use of anti-D immunoglobulin in pregnant women.
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BACKGROUND: Although testing to detect weak D antigens using the antihuman globulin reagent is not required for D− patients in many countries, it is routinely performed in Korea. However, weak D testing can be omitted in D− patients with a C−E− phenotype as this indicates complete deletion of the RHD gene, except in rare cases. We designed a new algorithm for weak D testing, which consisted of RhCE phenotyping followed by weak D testing in C+ or E+ samples, and compared it with the current algorithm with respect to time and cost-effectiveness. METHODS: In this retrospective study, 74,889 test results from January to July 2017 in a tertiary hospital in Korea were analyzed. Agreement between the current and proposed algorithms was evaluated, and total number of tests, time required for testing, and test costs were compared. With both algorithms, RHD genotyping was conducted for samples that were C+ or E+ and negative for weak D testing. RESULTS: The algorithms showed perfect agreement (agreement=100%; κ=1.00). By applying the proposed algorithm, 29.56% (115/389 tests/yr) of tests could be omitted, time required for testing could be reduced by 36% (8,672/24,084 min/yr), and the test cost could be reduced by 16.53% (536.11/3,241.08 USD/yr). CONCLUSIONS: Our algorithm omitting weak D testing in D− patients with C−E− phenotype may be a cost-effective testing strategy in Korea.