Resumen

GOMEZ, Mariángeles et al. Monochorionic twin gestations: Ultrasonography, Doppler and study of the placental vassels post parturition and his correlation with the occurrence of complications. Rev. argent. radiol. [online]. 2009, vol.73, n.2, pp.193-200. ISSN 1852-9992.

Objective: To correlate between the appearence of Intrauterine Fetal Growth Restriction (IFGR), Selective Intrauterine Fetal Growth Restriction (SIFGR), Twin-to-Twin Transfusion Syndrome (TTTS) and macroscopic findings of placentas in Monochorionic Twin Gestations. To determine the importance of ultrasound and Doppler findings. Materials and methods: Between January 2005 and January 2008 we diagnosed 8 monochorionic twin pregnancies. Chorionicity was determined with first trimester ultrasound screening. Follow-up scans were done to assess amniotic fluid volume, bladders, fetal weight and fetal Doppler ultrasound. Alter delivery, we cannulated and dyed umbilical arteries and veins in order to characterise vascular anastomoses. We also evaluated distribution of the placenta plate, and type of cord insertion (central, marginal or velamentous). Results: Follow-up scans revealed: 3 cases with selective intrauterine fetal growth restriction (SIFGR); 1 case with intrauterine fetal growth restriction (IFGR); 1 case with twin-to-twin transfusion syndrome (TTTS); and 3 normal pregnancies. Follow-up Doppler scans revealed: 4 cases with intermittent absent/reversed end-diastolic umbilical artery flow; 3 cases with signs of placental insufficiency; and 2 normal cases. Perinatal outcome: 1 case of twin-to-twin transfusion syndrome (TTTS); 2 cases of selective intrauterine fetal growth restriction (SIFGR); 1 case of intrauterine fetal growth restriction (IFGR); 4 healthy cases. Visual inspection of placental plate: equal placental sharing (6 cases); unequal placental sharing (2 cases). Types of cord insertion: both fetuses with marginal cord insertion (3 cases); both fetuses with central insertion (2 cases); one fetus with central and the other one with marginal insertion (2 cases); one fetus with marginal insertion and the other one with velamentous insertion (1 case). Vascular anastomoses: 6 cases presented arterio-arterial ansatomoses (AAA) and arterio-venous anastomoses (AVA) in both directions; 1 case showed AAA and AVA in only one direction; another case showed AVA in one direction without AAA. The only case of TTTS was related to the presence of AVA in one direction and the absence of AAA. Signs of placental insufficiency were seen in the case of intrauterine fetal growth restriction (IFGR). Both cases of SIFGR showed unequal placental distribution. Conclusions: Vascular anastomoses are present in all cases of monochorionic twin gestations. anomalies in the cord insertion are frequent in this type of pregnancies. Selective intrauterine fetal growth restriction is related to unequal distribution of the placental plate. Intermittent absent/reversed end-diastolic umbilical artery flow in one of the fetuses suggests there are arterioarterial anastomoses, which are supposed to protect against twin-to-twin transfusion syndrome.

Palabras clave : Monochorionic twin pregnancy; Transfusion syndrome; Growth restriction; Vascular anastomoses.

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