412 Letters to the Editor Prenatal diagnosis of transient abnormal myelo- poiesis in three fetuses with Down syndrome: heterogeneous ultrasonographic findings and outcomes Transient abnormal myelopoiesis (TAM) is diagnosed in approximately 10% of neonates with Down syndrome (DS) and progresses to life-threatening illness in 20% of cases. We describe here three cases of TAM which showed heterogeneous ultrasonographic findings and outcomes. The first case was of a 27-year-old woman at 32 + 5 weeks’ gestation with severe fetal hepato- splenomegaly (liver longitudinal diameter 78 mm and spleen longitudinal diameter 60 mm (> 2 SDs above ref- erence values 1,2 )) (Figure 1). At 34 weeks’ gestation, signs of fetal heart failure and increased middle cerebral artery velocity (> 1.5 SDs 3 ) were noted. In addition, liver and spleen dimensions increased to 85 mm and 65 mm, respec- tively. Given these findings, we opted to administer corticosteroids and deliver by Cesarean section. The neonate weighed 2110 g, fetal hemoglobin was 9.7 g/dL and the karyotype was 46XX,+21. Blood tests showed severe leukocytosis, with white blood cell (WBC) count 118.100/μL with 56% myeloblasts, anemia and coagu- lopathy. Treatment with cytarabine (1 mg/kg for 3 days) was started. After a brief period of clinical stabilization, the neonate died on the 11 th day postpartum. Placen- tal histology revealed placentomegaly and extravasated fetal myeloblasts in the perivillous space, representing involvement of the maternal compartment of the pla- centa (Figure 2). Maternal flow cytometry performed the day before delivery showed fetal cells in the maternal blood. The second case was of a 24-year-old woman with a fetus with cytogenetically confirmed trisomy 21 presenting at 33 weeks’ gestation with severe isolated Copyright  2017 ISUOG. Published by John Wiley & Sons Ltd. Ultrasound Obstet Gynecol 2018; 51: 409–413.