Vanishing Twin

A vanishing twin, also known as fetal resorption, is a fetus in a multi-gestation pregnancy which dies in utero and is then partially or completely reabsorbed by the twin.

The occurrence of this phenomenon is sometimes referred to as twin embolisation syndrome or vanishing twin syndrome (VTS), since the 1980s when twin pregnancies were made visible early on by means of ultrasound.

Occasionally, rather than being completely reabsorbed, the dead fetus will be compressed by its growing twin to a flattened, parchment-like state known as fetus papyraceus.

If the fetus is absorbed completely, there are usually no further complications to the pregnancy, other than first trimester vaginal bleeding. However, if the event occurs in the second or third trimester, serious complications may include premature labor, infection due to the death of the fetus, and hemorrhage. Even at the end of the pregnancy, a low-lying fetus papyraceus may block the cervix and require a cesarean to deliver the living twin.

The vanished twin can die owing to a poorly implanted placenta, a developmental anomaly that may cause major organs to fail or to be missing completely, or there may be a chromosome abnormality incompatible with life. Frequently the twin is a blighted ovum, one that never developed beyond the very earliest stages of embryogenesis.