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Fetal splenic artery peak velocity (SPA-PSV) at mid-pregnancy as a predictor of Hb Bart's disease.

PURPOSE
To determine the accuracy of splenic artery peak systolic velocity (SPA-PSV) in predicting fetal hemoglobin (Hb) Bart's disease at mid-pregnancy among fetuses at risk.


MATERIALS AND METHODS
Pregnant women at risk of having a fetus with Hb Bart's disease were recruited into the study at 18 - 22 weeks of gestation and underwent SPA-PSV measurement before cordocentesis. The final diagnosis used as a gold standard was based on fetal hemoglobin typing using high performance liquid chromatography (HPLC).


RESULTS
A total of 136 fetuses from 132 singleton pregnancies and 2 twin pregnancies were recruited into the study. The mean maternal age was 28.7 ± 5.4 years, the mean gestational age was 19.1 ± 1.02 weeks, and the incidence of Hb Bart's disease was 23.5 % (32 fetuses). Using SPA-PSV above 1.51 Multiple of Median (MoM) as a cut-off point, the sensitivity, specificity, positive predictive value and negative predictive value of SPA-PSV to identify affected fetuses was 84.4 % (32 from 36 cases), 98.1 %, 93.1 % and 95.3 % respectively. Nearly all normal fetuses had a normal SPA-PSV.


CONCLUSION
SPA-PSV assessment at mid-pregnancy may be used as an adjunct method to identify fetuses with Hb Bart's disease with high, but not perfect, accuracy and may reduce the risk from unnecessary cordocentesis in some fetuses.