Abstract: The widely used Quintero staging system in the estimation of twin-twin transfusion syndrome （TTTS） is still controversial. A new staging system including fetal cardiac function assessment and placental A-A anastomosis detection is proposed. Alternatives for TTTS treatment include serial amnioreduction, septostomy, and selective fetoscopic laser photocoagulation. In severe TTTS cases, these methods can be used in combination for optimal effect. The etiology of TTTS remains unknown, while vasoactive mediators may participate in the pathophysiology of TTTS. Mathematical models describing the onset and development of the four stages of TTTS may contribute to the role of placental vascular connections in the pathogenesis of TTTS.

Key words: Twin-twin transfusion syndrome, Diagnosis, Treatment, Pathophysiology