Vanishing Twin Syndrome

If you're taking fertility treatments to help you get pregnant, there's a higher chance that you could become pregnant with twins or multiples. Not all twin or multiple pregnancies end with all the babies reaching full term. Sometimes one of the fetuses disappears from the womb in a process that has been called the Vanishing Twin Syndrome.

Identifying Vanishing Twin Syndrome

In the days before ultrasounds and before the syndrome was officially recognized, VTS was identified by an examination of the placenta after delivery. If the fetus isn't completely reabsorbed then it can be flattened by its growing sibling(s) into a state that's known as fetus papyraceus where the fetus looks like a piece of parchment paper. Sometimes limbs and developmental features are visible depending on the gestational age of the fetus.

Nowadays ultrasounds allow a pregnant woman to see her developing babies as early as six to seven weeks gestation. She is told she is having twins or multiples at the early ultrasound. During a standard follow-up visit the doctor detects only one heartbeat with the Doppler. A second ultrasound is arranged to confirm that one fetus died. Some medical statistics suggest that VTS is very common with it happening in as many as 30 percent of multi-fetal pregnancies. It also tends to happen in women over 30.

The Cause

There is no known cause. There is nothing a mother can do to prevent this from happening just as there is nothing a healthy woman can do to prevent the miscarriage of a singleton. Sometimes an examination of the placenta shows placental or chromosomal abnormalities. Sometimes improper cord implantation is considered the cause.

Effects for Mother and Surviving Babies

First trimester vanishing fetuses don't usually cause any health problems for the mother or the surviving fetus. Often the deceased fetus will be reabsorbed into the placental tissue and amniotic fluid. There are often no symptoms typically associated with a miscarriage.

If the gestational time is a little later in the first trimester, then the deceased fetus may get compressed by its sibling(s) in a condition called fetus compressus. Or the fetus could get completely flattened and looks like a piece of parchment paper in a condition called fetus papyraceous. The pregnancy can continue as normal and the mother delivers a healthy baby (or two in the case of multiples).

There are more complications if this happens in the second or third trimester. Second or third trimester VTS is not as common, but can cause infection, pre-term labor or hemorrhaging. Careful medical monitoring and treatment is required and sometimes later Vanishing Twin Syndrome can end in the death of all babies.

Sometimes later term VTS results in remnants of the deceased fetus being found in the survivor in the form of a tertoma tumor containing tissue fragments, teeth, hair or bone. VTS after 20 weeks can increase the risk of the survivor having cerebral palsy.

Vanishing Twin Syndrome can be difficult emotionally for the mother whether it happens early in the pregnancy or later. Even if the other child or children survive, mothers (and fathers) need to understand and accept that it's okay to grieve the death of lost baby while still being happy about the surviving baby.


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