Vanishing twin syndrome

Vanishing twin syndrome, also known as fetal resorption is a fetus in a multi-gestation pregnancy which dies in the uterus. After the death of the fetus, it is partially or completely reabsorbed by the mother or twin. Practically, what happens is that a mother’s body miscarries a fetus in a twin pregnancy. When one of the fetuses disappears in the uterus during pregnancy, doctors usually suspect a vanishing twin syndrome. What actually happens is that placenta absorbs the fetal tissue of the dead twin.

Symptoms of vanishing twin syndrome

During the first trimester of pregnancy, a physician usually determines if the woman is carrying twins. Ultrasounds can be done early around six or seven weeks and identify a pregnancy as multifetal or not. Sometimes, upon the next regular check-up only one fetus or one heartbeat may be detected, indicating the possible vanishing twin. The physician may also notice a drastic decrease in hormone levels, which would be a strong indicator that a woman has experienced a loss. Symptoms of a vanishing twin usually start early in the first trimester and also include bleeding, cramping and pelvic pain. However, many women experience different symptoms with a loss of a fetus. Most of them do not even have any obvious symptoms. According to researches, women older than 30 are at a higher risk of vanishing twin syndrome.

Consequences of vanishing twin syndrome

The first trimester is the most fragile period in every pregnancy. However, if the vanishing twin syndrome occurs during this period there are no serious consequences to the mother or to the surviving fetus. Sometimes the vanishing twin syndrome takes place in the later pregnancy putting both mother and a surviving child at a higher risk. If the fetus dies at eight weeks or after, only the water from the tissues becomes reabsorbed. Deceased fetus is then flattened from the pressure of the surviving twin. The surviving fetus has a higher chance for developing complications such as cerebral palsy. At this point the pregnancy is classified as a high-risk pregnancy and is associated with possible threat of infections, preterm labor, obstruction of labor and hemorrhaging.

Causes of vanishing twin syndrome

The reason behind this syndrome is yet unknown, however scientists estimate that vanishing twin syndrome occurs in up to one out of every eight multifetus pregnancies. It was thought for a long time that non-right-handed and left-handed individuals may be the survivors of "mirror image" identical twinning. "Vanishing" twins are frequently encountered in pregnancies formed as a result of in vitro fertilization.