Acardiac Twin with Preserved Brain

The fatal acardiac syndrome is a rare complication of monochorionic twinning and is reported in 1 of 35,000 births. It is caused by arterioarterial and venovenous placental anastomoses leading to circulatory predominance of 1 twin. The donor ‘pump’ twin provides circulation for itself and for the recipient acardiac twin. The acardiac twin is usually grossly abnormal with severe reduction anomalies of the upper part of the body. We report a twin pregnancy, where a recipient twin initially by ultrasound was misdiagnosed as dead. In the third trimester the supposedly dead twin presented as an edematous acardiac twin without peripheral reduction defects and a nearly normally developed brain. An acardiac twin with a nearly normal external appearance and an almost normally developed brain, nourished by a surviving twin brother, has not previously been described in the literature.