congenital anemia non-immune hydrops fetalis alpha thalassemia Hb Bart's hydrops fetalis Alpha-thalassemia hydrops fetalis Alpha-thalassemia major Hb Bart's hydrops fetalis is the most severe form of alpha-thalassemia and is almost always lethal. It is characterized by fetal onset of generalized edema, pleural and pericardial effusions, and severe hypochromic anemia. Hemoglobin Bart's hydrops fetalis ICD10:D56.0 ICD9:282.49 MONDO:0015579 Orphanet:163596 SCTID:5300004 homozygous alpha0-thalassemia