A 38-year-old woman (G1P0), with non-contributive family history, was referred to our antenatal unit at 27 weeks of pregnancy due to an abnormal mass of the placenta. The amount of amniotic fluid was normal and fetal growth was in normal limits. Her first trimester sonography and triple test were normal.
The exam demonstrated:
The "abnormal mass of the placenta" actually had a central arterial pulsation with a peripheral venous flow and turned out to be an acardiac fetus in a monochorionic, monoamniotic twin pregnancy;
The umbilical cord of the acardiac fetus was near the cord of the normal fetus, but independent;
The morphology of the normal fetus was without anomalies except for the dilatation of the abdominal course of the umbilical vein.
The patient refused umbilical cord embolization of the acardiac twin. An amniocentesis was done, revealing normal karyotype (46,XX). The size of the acardiac twin stayed the same during the follow-up examinations, but the normal twin developed signs of cardiac decompensation at 34 weeks, and the pregnancy was terminated by a cesarean section. The normal neonate weighted 2000 g and its postnatal adaptation was without complications. The acardiac twin was without recognizable organs and was described as an acardiac amorphus twin.
Images 1, 2: The image 1 shows the placenta (left part of the image) and transverse scan of the acardiac twin (right part of the image). The image 2 shows a mass of the acardiac twin imitating a mass arising from the placenta.
Images 3, 4: The images show transverse color Doppler scans of the acardiac twin.
Images 5, 6: The images show transverse color Doppler (image 5) and 3D (image 6) scans of the acardiac twin.
Images 7, 8: The images show transverse gray scale scans of the acardiac twin.
Images 9, 10: The image 9 shows the placental insertion of the umbilical cord of the normal twin (left part of the image) and insertion of the umbilical cord of the acardiac twin (right part of the image).
Images 11, 12: The images show an arterial pulsation within the acardiac twin (image 11) and venous peripheral flow of the acardiac twin (image 12).
Images 13, 14: The image 13 shows dilated abdominal part of the umbilical vein of the normal twin. The image 14 shows a normal ductus venosus flow of the normal twin.
Images 17, 18: Postnatal appearance of the placenta (image 17) and the mass of the acardiac twin (image 18).
Video 1: The video shows the acardiac twin.