OBJECTIVES:

To determine the sensitivity and
specificity of middle cerebral artery peak systolic velocity (MCA-PSV) in
mid-pregnancy for the identification of homozygous alpha-thalassemia-1
(hemoglobin (Hb) Bart's disease) in fetuses at risk of the disease.

METHODS:

A total of 88 pregnancies (91 fetuses) at
risk of Hb Bart's disease and undergoing MCA-PSV measurement before
cordocentesis at 18-22 weeks of gestation were recruited into the study.
Definitive diagnosis was made using the gold standard technique of Hb typing by
high-performance liquid chromatography.

RESULTS:

The mean +/- SD age of the 88 pregnant
women recruited into the study was 28.3 +/- 5.7 years, the gestational age was
18.8 +/- 1.1 weeks and the incidence of Hb Bart's disease was 22% (20 fetuses).
Using MCA-PSV above 1.5 multiples of the median as a cut-off point, the
sensitivity of MCA-PSV for detecting affected fetuses was 85% (17/20 cases),
with a specificity of 100%, and positive and negative predictive values of 100%
and 95.9% respectively. Three of 20 fetuses with Hb Bart's disease had normal
MCA-PSV.

CONCLUSIONS:

MCA-PSV assessment in mid-pregnancy is a
useful method for identifying Hb Bart's disease with high sensitivity and
specificity among fetuses at risk, and may allow avoidance of unnecessary
cordocentesis in some cases.