Means rapid acute blood loss from the circulations of one twin to the other twin via large superficial anastomoses. This happens most often during delivery. The twins differ in color (anemic versus plethoric) but compared to chronic twin transfusion intrauterine growth is symmetric and also the hearts of these twins are of the same weight.
Acute peripartum transfusion superimposed on chronic prenatal twin transfusion obscures the typical color difference between the donor and the recipient (as described in previous chapter). In such a case the donor looks paradoxically plethoric and the recipient is paradoxicaly pale. The most reliable sign of chronic twin transfusion syndrome is thus heart hypertrophy in recipient. The color or hematocrit levels are rather confusing.
Acute transfusion also occurs in utero after the death of one twin, this means that the surviving fetus bleeds into the circulation of the dead one. Detrimental sequelae in the surving twin:hypoxic/ischemic brain lesions, bowel atresia, aplasia cutis.
The chronic recipient is paradoxically anemic, chronic donor is paradoxically plethoric: Twins, fetofetal transfusion, acute, Macro, autopsy (72419)
Heart hypertrophy, recipient; donor is anemic: Twins, fetofetal transfusion, paradoxical hyperemia of the donor, Macro, autopsy (72420)