A novel ultrasound-based approach to investigate extramedullary haematopoiesis in foetal spleen.

Foetal spleen is described as a transient focus of haematopoiesis between the 3 and 5 month of gestation: this function is however entirely replaced by the bone marrow before the end of pregnancy. This study identifies haematopoiesis in foetal spleen by exploring changes of echogenicity during its development throughout gestation. Two intervals of pregnancy were studied: Mid-Pregnancy (Mid-P, 19-23 weeks) and End-Pregnancy (End-P, 37-41 weeks).