Vanishing twin

A phenomenon in which one twin in a multiple pregnancy disappears in the uterus during pregnancy as a result of miscarriage of one twin or multiple.

Vanishing twin

Fetus papyraceus, a mummified fetus that results from a vanishing twin.

A vanishing twin is a phenomenon that occurs in a multiple pregnancy when one of the fetuses dies in the uterus and is partially or completely reabsorbed by the mother or the surviving twin. This can happen at any time during the pregnancy, but it is most commonly observed in the first trimester.

Causes

The exact cause of a vanishing twin is not always known, but it is believed to be due to a variety of factors. These can include chromosomal abnormalities, placental insufficiency, or other developmental issues that prevent the twin from surviving. In some cases, the body may naturally reabsorb the tissue of the deceased twin, while in others, the tissue may remain and become compressed, leading to a condition known as fetus papyraceus.

Diagnosis

The diagnosis of a vanishing twin is often made during a routine ultrasound examination. Initially, two gestational sacs or two embryos may be visible, but in subsequent scans, one may no longer be present. The remaining twin usually continues to develop normally, although there may be some increased risk of complications depending on the timing and cause of the vanishing twin.

Implications for the surviving twin

In most cases, the surviving twin is not adversely affected by the loss of the co-twin. However, there can be some risks depending on the stage of pregnancy and the cause of the vanishing twin. These risks can include preterm birth, low birth weight, or other complications. It is important for the pregnancy to be monitored closely by healthcare professionals.

Fetus papyraceus

Another view of fetus papyraceus.

When a twin dies in utero and is not completely reabsorbed, it may become compressed by the growing surviving twin. This results in a flattened, parchment-like appearance known as fetus papyraceus. This condition is rare and is usually discovered during delivery or through imaging studies.

Related pages

• Multiple birth
• Miscarriage
• Ultrasound
• Chromosomal abnormality