[Sonographic findings of acardiac twin in the first trimester of pregnancy]. / Sémiologie échographique du foetus acardiaque au premier trimestre de la grossesse.

ABSTRACT

Twin Reversed Arterial Perfusion (TRAP) sequence, or the acardiac anomaly, is a rare complication of monozygotic twins, that occurs in approximately 1 in 35,000 births. In the first trimester, once the diagnosis of monochorionic twins is made, particularly if one embryo shows abnormal development or generalized edema, the TRAP sequence must be considered. Moreover, malformations reported in the perfused twin are often severe. Diagnosis is confirmed by using Doppler ultrasound which demonstrated the presence of retrograde perfusion in the umbilical cord of the abnormal twin. The more complete the body form is, the more similarity the vascular relationships have to the pattern found in a full-term fetus. Final outcome and treatment decisions can be determined based on hemodynamic criteria. We report a case of a misdiagnosed TRAP sequence with no structural malformations detected by ultrasonography at 12 weeks of gestation.