Vanishing Twin Syndrome- Signs, Causes & Effect

Vanishing Twin Syndrome

Vanishing twin syndrome was discovered in 1945. As the name suggests, when a twin or multiple disappears in the uterus due to miscarriage of one twin or multiple, is known as Vanishing twin syndrome. The fetal tissue is then absorbed by the other twin, multiple, mother or placenta, hence giving an appearance of a ‘vanishing twin’. 

How is it detected?
Times when ultrasound was not used, miscarriage of a twin or multiple was detected after delivery when the placenta examined. With the help of ultrasound, the presence of twins or multiple is detected as early as first trimester. In case of disappearance of a twin, a follow-up ultrasound can confirm the same. 

For instance, when a woman goes for an ultrasound around 6-7 weeks of  gestational age, she will be informed by her doctor if she is carrying two fetuses. At her next visit, if the doctor is only able to hear one heartbeat using doppler, then doctor will advise her to go for a second ultrasound to observe the other fetus. In some cases, the women may also experience symptoms that will indicate a miscarriage.

With the help of ultrasound, the detection of this condition has become easy. Vanishing twin syndrome has been estimated to affect 21-30% of multifetal pregnancies.

Why does it happen?

Symptoms that result in this condition are said to be present from the start of pregnancy and do not occur suddenly. Although, in most cases, the cause still remains a mystery.

Careful observation of placenta and/or fetal remains can help in identifying unusual aberrations in the chromosomal makeup of the vanished twin. Problems with umbilical cord can also be a cause.

Is this going to affect the mother and the surviving twin ?

If the miscarriage happens in the first trimester, neither the mother nor the surviving twin is at any risk. Although, the health of other twin also depends on why the miscarriage happened in the first place. If the loss happens in the later stages of pregnancy, the risks to the surviving twins increases, including a high rate of cerebral palsy.   

After the loss of a twin in the embryonic period of gestation, the amniotic fluid, water within the twin’s tissues and the placenta maybe reabsorbed. This results in the flattening of the deceased twin due to the pressure of the surviving twin. The deceased fetus may be identified as fetus compressus (flattened out) or fetus papyraceous (fetus devoid of water and tissues).

Who is more vulnerable to it?
Women crossing 30 are more vulnerable to it, as per research. Bleeding, pelvic pain in the uterus are some symptoms that may develop early in the first trimester.
What now?
If the twin dies in first trimester, no complications arise for either the surviving twin or the mother generally. Things may take a downturn if the fetal death happens in second or third trimester.

In case of bleeding, uterine cramps and pain in the uterus, doctor should be referred to. A lot of times, the women wait for a natural miscarriage.It is very important to observe the growth of other twin closely. 

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