Vanishing Twin Syndrome

It’s been a slow couple of weeks in infertility news, hence the lack of updates. I did see this interesting post on Sharon’s blog that I thought I’d share here.

I know a few people who went through this and might appreciate this info:

What is the cause of Vanishing Twin Syndrome?
Vanishing twin syndrome was first recognized in 1945. Vanishing twin syndrome is when one of a set of twin/multiple fetuses disappears in the uterus during pregnancy. This is the result of a miscarriage of one twin/multiple. The fetal tissue is absorbed by the other twin/multiple, placenta or the mother. This gives the appearance of a “vanishing twin”.

How is Vanishing Twin Syndrome identified?
Before the use of ultrasound, the diagnosis of the death of a member of a multiple pregnancy was made through an examination of the placenta after delivery. Today, with the availability of early ultrasounds, the presence of twins or multiple fetuses can be detected during the first trimester. A follow-up ultrasound may reveal the “disappearance” of a twin.

For example, a woman may have an ultrasound at 6 or 7 weeks gestation. The doctor identifies two fetuses and the woman is told she is having twins. When the woman returns for her next visit, only one heartbeat can be heard with Doppler. A second ultrasound is conducted and only one fetus is observed.

Sometimes a woman may have symptoms that would indicate a miscarriage, yet, with an ultrasound, a single baby is found in her uterus.

Vanishing twin syndrome has been diagnosed more frequently since the use of ultrasonography in early pregnancy. A conservative estimate of frequency is that vanishing twin syndrome occurs in 21-30% of multi fetal pregnancies. Research from a European series of pregnancies associated with assisted reproductive technology (ART) show that 10-15% of singleton births were initially twin gestations.

First trimester: Morbidity when vanishing twin syndrome occurs during the first trimester is limited. The mother is most likely to develop mild vaginal bleeding and cramping. If the event occurs later in the first trimester, morbidity may be similar to that of the second and third trimesters.
Second and third trimesters: Maternal complications include premature labor, infection from a retained fetus, severe puerperal hemorrhage, consumptive coagulopathy, and obstruction of labor by a low-lying fetus papyraceus causing dystocia and leading to a cesarean delivery.
The diagnosis of vanishing twin in a pregnancy significantly increases both preterm (<37 gestational weeks) and very preterm (<32 gestational weeks) births.