Duplicity: Sonography suggested a twin gestation was dichorionic–and monochorionic




Case notes


A dichorionic twin pregnancy was diagnosed in a 26-year-old woman after first- and second-trimester ultrasounds identified a twin peak sign. However, at 23 weeks’ gestation, sonographic findings consistent with Quintero stage III donor twin-twin transfusion syndrome (TTTS) developed. After counseling on management options, the patient decided to proceed with diagnostic fetoscopy and selective laser photocoagulation of communication vessels if vascular communications were identified.




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Conclusions


Diagnostic fetoscopy revealed a midline “bridge” of placenta that contained 9 vascular communications. The middle portion of the dividing membranes appeared thin and translucent, which is typical of monochorionic-diamniotic twins; the lateral portions of the dividing membranes were thick and more opaque in appearance, consistent with dichorionic-diamniotic twins ( Figure 1 ). A distinct line demarcating the transition from monochorionicity to dichorionicity was visible in the dividing membranes ( Video Clip ). Selective laser photocoagulation of communication vessels was performed as previously described elsewhere. Of note: 2 placental vessels tunneled within the placenta and emerged remotely.




FIGURE 1


Fetoscopic view of donor’s foot is seen though dividing membranes at 23 weeks’ gestation. Left portion of dividing membranes is translucent, consistent with monochorionicity; right side is opaque and relatively thicker, consistent with dichorionicity.

Chmait. Duplicity. Am J Obstet Gynecol 2011.


The patient delivered at 28 weeks’ gestation due to premature rupture of membranes followed by preterm labor. Gross examination of the placenta disclosed a hybrid monochorionic/dichorionic placenta ( Figure 2 ). Histological evaluation of the transitional zone in the dividing membranes confirmed the absence of intervening chorion within the monochorionic portion ( Figure 3 ). Placental injection studies revealed no residual patent anastomoses.


May 28, 2017 | Posted by in GYNECOLOGY | Comments Off on Duplicity: Sonography suggested a twin gestation was dichorionic–and monochorionic
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