Were it not for an ultrasound when she was 10 weeks pregnant, Jane Nungari might not have known about the the baby who vanished in her womb.
She left the sonographer’s office after her first scan and called her husband, then her family. She was carrying twins! It was exciting, but not surprising as she comes from a family of twins – her dad has one and so does she. She had often wondered if she would have twins herself, and was happy that indeed she would, starting with her first pregnancy.
However, at the 20-week scan, the ultrasound technician told her to see the gynaecologist to explain what he had found – she was no longer carrying two babies, but one.
“He explained that I had experienced the vanishing twin syndrome. I was astounded,” she recalls.
First recognised in 1945, the vanishing twin syndrome is a rare condition, where in an initial twin pregnancy, one of the embryos dies in the womb and the foetal tissue is absorbed by the mother, the remaining twin or the placenta.
“During the early stages of pregnancy, the Doppler ultrasound may detect two gestational sacs, only for a subsequent ultrasound to detect only one foetal heartbeat. The other gestational sac already disappeared with the evidence of the second baby. It can happen to women with fraternal or identical twins, although it is more common with twins sharing the same placenta,” explains Dr Nelly Bosire, a gynaecologist.
For Jane, the loss of the twin was painful, even though no body parts had formed.
“It felt like I had lost an actual baby, but I didn’t know how to grieve for it without sounding ungrateful for the surviving twin. I became more protective of the remaining baby, and any slight uncomfortable feeling was a cause for alarm,” she says.
The remaining baby was carried to term and delivered, and is now seven years old.
VANISHING TWIN SYNDROME
Doctors still don’t understand why the vanishing twin syndrome happens, but it has been linked to chromosomal abnormalities or improper cord implantation.
“When the twins share a placenta, but have different umbilical cords, the flow of blood might favour one twin. The favoured one grows, while the other remains like an empty envelope. The smaller it is, the more likely it is to disappear,” explains Dr Bosire, adding that if a pregnant woman does not go for an ultrasound during the first trimester, she may never know that she had initially been expecting twins.
During her second pregnancy, Jane didn’t go for an ultrasound scan until she was about 22 weeks pregnant.
This time, it was a singleton pregnancy. However, during delivery, the midwives pulled out what seemed like the remnant of another twin, or what Dr Bosire says is called a foetus papyraceus.
"When the other twin is not fully absorbed, there might be a 'mummified' or compressed foetus, or subtle abnormality on the placenta such as a cyst," she explains, adding that there are hardly ever tell-tale signs of the loss of the other twin if it happens in the first trimester. However, some women may experience uterine cramps, spotting or pelvic pain after the loss.
Women with multiple pregnancies are advised to have an ultrasound on all three trimesters, so they don’t prepare for more than one kid, only for one to be delivered, in the event of vanishing twin syndrome.
“It becomes really tough trying to explain to a woman that she only delivered one baby, when she is convinced she carried more than one,” explains Dr Bosire. Moreover, close monitoring helps to ensure all babies are safe.
“If one baby stops growing later in the pregnancy and is not fully absorbed, complications may arise from the dead tissue retained in the womb. It might consume the clotting factor and cause spontaneous bleeding. It also makes a perfect medium for bacteria to grow."
There is nothing pregnant women can do to prevent the vanishing twin syndrome, especially if it happens in the early stages of pregnancy. Doctors can only safeguard the remaining baby.
If it happens much later, delivery can be accelerated and the woman will end up with premature babies.