The main determinant of fetal outcome in twin pregnancy is placental chorionicity: monochorionic twins have a three to five higher risk of perinatal loss and handicap in comparison to dichorionic.

Twin pregnancies are at significant risk for adverse outcome with perinatal mortality and morbidity rate three to six times that of singletons. Twin pregnancies account for 1–2.5% of all pregnancies 1 the prevalence of twins showed an increase of approximately 80% since the beginning of the 1970s, mainly due to the increase of the maternal age at conception over this period and to the widespread diffusion of the assisted reproduction technology. En este artículo se revisan las características ecográficas que ayudan a la descripción exacta de la corionicidad. Esto último es, sin duda, la herramienta más útil y valiosa: la separación de la membrana de la superficie placentaria muestra una típica forma «lambda» en el embarazo bicoriónico y un típico signo en «T» en el monocoriónico. Por esta razón, el diagnóstico de corionicidad en gemelos es de importancia clínica, ya que así se podrá planificar una mayor vigilancia en gestaciones monocoriónicas y detectar la aparición de complicaciones en las primeras etapas.ĭistintos signos ecográficos sirven para evaluar la corionicidad: número de masas placentarias, sexo de los fetos, características de la membrana intergemelar. Esto se debe principalmente a las complicaciones asociadas con la corionicidad, a saber, el síndrome de transfusión fetal-fetal (STFF), la restricción del crecimiento fetal selectivo (CIR) y la perfusión arterial reversa (secuencia TRAP), que son debidas a anastomosis vasculares intergemelares en la placenta común.

La corionicidad es el principal determinante del desenlace perinatal en los embarazos gemelares: la morbimortalidad perinatal es significativamente superior en los gemelos monocoriónicos que en los bicoriónicos. In this article the sonographic features that help in the accurate depiction of chorionicity are reviewed. The last one is surely the most useful and valuable tool: the take-off of the membrane from the placental surface shows the typical “lambda” appearance in dichorionic pregnancy and the typical “T” appearance in the monochorionic ones. For this reason the diagnosis of chorionicity in twins is of clinical importance in order to plan an increased surveillance in monochorionic gestations and to recognize the appearance of complications in their early stages.ĭifferent sonographic signs may be used to evaluate chorionicity: number of placental masses, sex of the fetuses, characteristics of the intertwine membrane. This is mainly due to complications associated specifically with monochorionicity, such as twin to twin transfusion syndrome (TTTS), selective fetal growth restriction (FGR) and twin reverse arterial perfusion syndrome (TRAP), consequences of the presence of inter-twin vascular anastomoses in the common placenta. Chorionicity is the main determinant of the perinatal outcome in twin pregnancies: perinatal mortality and morbidity are significantly higher in monochorionic versus dichorionic twins.

Triplets sonogram