Late onset of discordant growth in a monochorionic twin pregnancy: Vascular anastomoses determine fetal growth pattern and not placental sharing

Twin-twin transfusion syndrome in monochorionic twin pregnancies has a comp lex and variable clinical presentation. We present the first documented cas e where two unidirectional arteriovenous anastomoses connecting the donor t win's larger with the recipient's smaller placental part produce late onset of discordant growth and subsequent twin-twin transfusion syndrome. We con clude that the haemodynamic effects of the anastomoses caused the observed discordant fetal development and not the unequally shared placenta. Copyrig ht (C) 2001 S. Karger AG, Basel.