Twin–twin transfusion syndrome with only superficial placental anastomoses: endoscopic and pathological evidence

Deep arteriovenous placental anastomoses in monochorionic placentas have been considered an essential etiological factor in twin–twin transfusion syndrome (TTTS). Moreover, some investigators have suggested that superficial anastomoses have a protective role. We report on confirmed cases of TTTS with only superficial anastomoses.