Fetal septum primum excursion (SPE) and septum primum excursion index (SPEI) as sonomarkers of fetal anemia: using hemoglobin Bart's fetuses as a study model.

OBJECTIVES: The objectives the study are to evaluate the effectiveness of septum primum excursion (SPE) and SPEI (SPE index, a ratio of SPE to left atrial diameter) in predicting fetal hemoglobin (Hb) Bart's disease and to determine the correlation between Hb levels and SPE/SPEI METHODS: The database of Cardio-STIC volume datasets (VDSs) of fetuses at risk of Hb Bart's disease at 18 to 22 weeks was assessed. The VDSs were blindly analyzed offline for measurements of SPE and SPEI.

RESULTS: Of 180 VDSs recruited, 44 were acquired from fetuses with Hb Bart's disease, while 136 were derived from unaffected fetuses. SPE and SPEI was inversely correlated with Hb levels (p < 0.0001). The SPE and SPEI were significantly higher in the affected group (4.1 + 1.1 mm vs 3.0 + 0.8 mm and 0.61 + 1.1 vs 0.49.1 + 0.1, respectively). SPE, at cut-off 1.3 multiple of median, gave a sensitivity and specificity of 75.0% and 72.7%, respectively, but less than a sensitivity (81.4%) and specificity (95.4%) of middle cerebral artery peak systolic velocity.

CONCLUSIONS: In anemic fetuses, SPE and SPEI was inversely correlated with Hb level. Additionally, SPE, better than SPEI, may be used as an adjunctive sonographic sign to predict Hb Bart's disease but its accuracy of prediction is not good enough to be used independently or as a diagnostic test. © 2016 John Wiley & Sons, Ltd.