Prenatal diagnosis and management of homozygous hemoglobin constant spring disease.

Objective: To describe fetal management of homozygous hemoglobin constant spring (Hb CS).

Methods: Six fetuses with homozygous Hb CS disease undergoing intrauterine transfusion (IUT) were comprehensively reviewed. Additionally, when combined with 8 cases previously reported, a total of 14 cases were analyzed.

Results: The first clues of diagnosis were hydropic changes suggesting fetal anemia. Increased cardiothoracic diameter ratio (CTR) was the most sensitive sonographic marker but slowly changed after IUT, whereas MCA-PSV was the most sensitive in response to IUT. Pre-IUT Hb varied from 1.1% to 6.8%. Gestational age at diagnosis was 17-29 (22.8 ± 3.3) weeks. Rates of adverse obstetric outcomes were relatively high; preterm birth: 35.7%, low birthweight: 42.9%, and fetal growth restriction: 28.6%. All showed good response to IUT with disappearance of hydropic signs and all survived without short-term complications. Their anemia gradually improved in childhood and transfusion independent.

Conclusion: Homozygous Hb CS can cause severe fetal anemia. Early diagnosis and IUT can improve neonatal outcomes, probably preventing adult diseases caused by fetal programming.