Curious case of the vanishing twin syndrome

Monday August 03 2020

Imagine going to hospital unsure of whether you are pregnant but the scan soon confirms that you are pregnant with not just one baby but twins. Depending on your situation, there is always that confusion but you recover and realise you are going to have twins. In most Ugandan cultures, having twins automatically elevates a woman’s status in the community.

While others are mothers, a mother of twins is given the reverential name of Nalongo and Salongo for the father. But on your next visit, you receive the devastating news that you are now carrying just one baby. “Where did the other one go?” You wonder. Dr Joseph Isangha, an obstetrician at Case Hospital in Kampala, says this is a case of vanishing twin syndrome.
What happens?
“Vanishing twin syndrome is when a foetus in a multigestation pregnancy dies in the uterus. It is a spontaneous loss or miscarriage of one developing baby early in a multiple pregnancy usually resulting in a normal singleton pregnancy. If the miscarriage occurs before eight weeks of gestation, the water and fluids from the miscarried embryo are reabsorbed and there is nothing to be seen, he says adding that however, if the miscarriage happens after this time, the tiny, compressed foetus can sometimes be seen at the birth of the other twin as they are both expelled from the uterus,” he says.
The phenomenon is relatively common and is believed to happen in 20 to 30 per cent of pregnant mothers. “It is common for early ultrasound scan to detect two gestational sacs but later on, only one foetal heartbeat is detected and the second sac disappears or in a subsequent ultrasound scan, one normally developing baby is present alongside a brightened ovum,” says Dr Isangha.

Studies show that vanishing twin syndrome occurs before the 12th week of gestation in around 36 per cent of pregnancies with two gestations and more than 50 per cent of pregnancies with three or more gestations. The syndrome may be even more prevalent but due to lack of early ultrasound scanning, many cases may be missed.

Mothers with vanishing foetal syndrome may show no symptoms at all or experience those that accompany a miscarriage such as per vaginal bleeding and lower abdominal cramping.

However, there are some signs that you might be experiencing a vanishing twin. If you experience a temporary decrease in pregnancy symptoms (nausea or fatigue), spotting, or cramping, you should contact your doctor immediately. Dr Isangha cautions against taking these signs too seriously, however, because spotting is common in early pregnancy and the “vast majority” of spotting is not related to a vanishing twin.
The causes are not exactly understood but research has pointed to chromosomal abnormalities in the lost baby.
“In most cases, twins “vanish” because they have chromosomal abnormalities. Most miscarriages are due to chromosomal (genetic) abnormalities with the embryo, creating a foetus that never would have been viable in the first place. Sometimes there is improper cord implantation which can also result in the loss of a twin,” he says.

Although the syndrome is relatively common, researchers report that there are more cases of vanishing twin syndrome in women older than 30, though that may be due to the fact that older mothers in general have higher rates of multiple pregnancies, especially with the use of fertility treatments.
Can it prevented?
Even more concerning is that as common as the syndrome is, experts are yet to identify preventive measures. “There is nothing that can be done since the major cause is thought to be an interruption to the embryo’s developing genetic structure. This is completely out of the control of the mother or her partner. While it is a sad occurrence, doctors believe it happens for the best since the vanished twin is believed to have significant obstetric problems,” he explains.
Will surviving twin be affected?
While in the majority of cases, the surviving twin is not affected by the miscarriage and grows to full gestation without any complications, recent studies have found that around 7 per cent of women who have experienced Vanishing Twin Syndrome will deliver the other baby or babies prior to 28 weeks of gestation.


There is also an increased risk of the surviving baby or babies having low birth weight and the health risks associated with this. There is also potentially a greater risk of the surviving twin/triplet having health issues later in life. It is, therefore, advisable to have your pregnancy monitored extra carefully.

Emotional effects
Dr Joseph Isangha, an obstetrician, says: “It is emotional telling a mother expecting a multiple pregnancy that they have lost one of their foetuses. Some even question your expertise and seek a second opinion. If you are unable to cope with the loss, Dr Isangha suggests counselling to work through your feelings.”

Your emotions after a miscarriage: The stages of grief

Whenever a pregnancy loss happens, you are likely to experience many feelings and reactions. Although you cannot wish them away, understanding them will eventually help you come to terms with your loss.

Many people who suffer a loss of any type go through a number of steps on their road to emotional healing. These steps are common, though the order in which the first three occur may vary and so, too, may the feelings you experience.

Shock and denial: There may be numbness and disbelief, the feeling that “this could not have happened to me.” This is a mental mechanism designed to protect your psyche from the trauma of loss.

Anger and guilt: Desperate to pin the blame for such a senseless tragedy on something, you may blame it on yourself (“I must have done something wrong to cause the miscarriage” or “If I had been happier about the pregnancy, the baby would still be alive.”). Or you may blame others — God, for letting this happen, or your practitioner, even if there is no reason to. You may feel resentful and envious of those around you who are pregnant or who are parents, and even have fleeting feelings of hatred for them.

Depression and despair: You may feel sad most or all of the time, cry constantly or be unable to eat or sleep. You may also have no interest in anything or be unable to otherwise function, and may wonder if you will ever be able to have a healthy baby.

Acceptance: Finally, you will come to terms with the loss. Keep in mind that this does not mean you will forget the loss, but that you will be able to accept it and get back to the business of life.
If you have suffered a miscarriage, it is important to remember that you have the right to grieve as much or as little as you need to. Do this in any way that helps you to heal and eventually move on.
Turn to your partner for support. Remember that he or she is mourning the loss of a baby too but may show that grief in a different way. Sharing your feelings openly with each other, rather than trying to protect each other, can help you both heal.

If you are religious, ask your spiritual leader for guidance. Sharing your feelings through a support group, with a friend or online with others who experienced a miscarriage can also be a comfort. Ask your practitioner to recommend a therapist or bereavement group to help you through this difficult period.