TRAP sequence, embolization

Fernando Heredia, M.D., Victor Quiroz, M.D.

Departamento de Obstetricia y Ginecología, Facultad de Medicina, Universidad de Concepción.Servicio de Obstetricia y Ginecología, Hospital Guillermo Grant Benavente, Concepción, Chile.

Case report:

This is a 25-year-old G2P1, who was referred to our center at 14 weeks of gestation, after an outside scan suggested the death one twin.
Our diagnosis was a twin gestation complicated by TRAP sequence with an acardic-acephalus twin. We decided to observe sonographically the evolution of this pregnancy.
At 16 weeks of gestation the acardic twin had grown rapidly reaching  a 70% of the weight of the pump twin. There was no polyhydramnios at that time, but heart failure was probably imminent.

The acardiac twin is on the left. Note the large acardiac compared to the pump twin.

compared size 16 weeks

The next set of images show the acardic-acephalus in detail at 17 weeks: severe edema, cystic hygromas and apparently normal lower limbs.

aacystic hygromas

22 weeks: Acute polyhydramnios (AFI= 26, deepest amniotic pocket >12 cm).

The following image demonstrates the short cord, giving the acardic fetus the appearance of being hanged from its placental insertion. Also, note the reversed perfusion in the umbilical artery (blue going away from the transducer).

short cord 2
reversed perfusion1

There are also 2 video clips available that show the proximity of both cord insertions and how the acardic fetus moved it's feet.
Video clip-1   Video clip-2

After discussing the situation with both parents, we performed a percutaneous intra fetal embolization with absolute ethylic alcohol. The procedure was guided by Doppler ultrasound. No previous amniodrainage was performed nor digitalin were given to the mother.

This is the video clip which shows all the process of embolization and the "white out effect√Ę‚ā¨ with interruption of the acardic's circulation.
The pump twin showed a transient bradycardia, which lasted only 3 minutes. (1st minute: 45 - 60 b.p.m.; 2nd minute: 55 - 80 b.p.m.; 3rd  minute 115-130 b.p.m.) No other immediate heart failure signs after the procedure appeared. 8 hours later the pump twin remained alive, with normal umbilical artery doppler. However, 15 hours later, the pump twin was found dead.

Labor was induced and 10 hours later both fetuses were vaginally delivered with no complications for the mother. The acardic fetus weighted 450 gr and the pump twin 480 gr. The placenta weighted 500 gr.
Pathological analysis of the pump twin's cord showed acute sclerosis signs which confirmed our suspicion that alcohol was also delivered to the normal twin thus resulting on his death.

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