Placental pathology

Placental pathology and twin–twin transfusion syndrome

Twin–twin transfusion syndrome (TTTS) was initially characterized by Friedrich Schatz in the late 1800s. This body of work included a case of a monochorionic twin pregnancy that was complicated by marked discordance of infant size at birth.1–5 The larger twin was noted to be edematous and found to have micturated frequently prior to death at 12 hours of age, while the smaller co-twin never urinated and died at 53 hours of age with an empty bladder. 

From detailed study of monochorionic placentas, Schatz suggested that anastomotic vessels linked the circulations of monochorionic twins. The presence of these vascular anastomoses served as a conduit for the unbalanced exchange of blood between the twins, thus setting up the circumstances for the development of TTTS. To better understand the etiology and management of TTTS, a detailed understanding of the placenta is required. The aim of this chapter is to review placental anatomy and related pathophysiology as it pertains to TTTS.