Yes, you can have a hidden twin, usually a "vanishing twin" absorbed early in pregnancy, or rarely, a concealed twin missed by ultrasounds until later, but advanced imaging makes late discoveries very uncommon; sometimes a parasitic twin can even grow inside another, a rare condition called fetus-in-fetu.
How is vanishing twin syndrome diagnosed? Your provider may diagnose vanishing twin syndrome during a pregnancy ultrasound. If one of the embryos present on an earlier ultrasound is no longer present on a future ultrasound, your provider can make a vanishing twin syndrome diagnosis.
A concealed twin pregnancy can occur, but it is very rare with the current ultrasound. In the early weeks, one of the twins can be hidden from view by positioning, limitations in equipment, or other reasons. But by mid-pregnancy, nearly all such cases are identified.
In some cases, one twin may be more difficult to see or may be hidden behind the other twin. Additionally, if the ultrasound is performed too early in the pregnancy, there may not be enough development to spot a second embryo.
Many women might not even realise they were carrying twins, as the only signs can be mild symptoms like slight cramping or bleeding. Early ultrasound scans may initially show two gestational sacs, but later only one is visible.
Vanishing twin syndrome is a condition in which 1 fetus in a multiple gestation disappears in the uterus during early pregnancy, most often during the first trimester.
However, after 20 weeks of pregnancy, the fetuses have grown enough that a second fetus would be clearly visible on ultrasound, and it would be very unlikely that there is another baby hidden in the womb.
The most common reasons for a pregnancy not showing on an ultrasound scan are: it is too soon to see the baby on the scan - you usually cannot see before 6 weeks. you've had a miscarriage. the pregnancy is outside the womb (ectopic pregnancy)
Even if you are pregnant with twins, there's no guarantee you will produce hCG any sooner than if you were pregnant with one baby. But because your levels may be higher, it is possible to detect a pregnancy slightly earlier due to higher levels of hCG.
In the majority of cases, the surviving twin is not affected by the miscarriage of the other. They continue to grow and mature to full gestation without any complications.
Unless it's too early in your pregnancy to see the baby (up to around 8 weeks), it's unlikely the baby can be hiding from the ultrasound. The baby grows in its sac and can't move outside of this. The scan can cover this area entirely, so it's very unlikely that the baby can be out of view.
The gene for hyperovulation can come from either side of the family, but the woman would need to have the gene in order for the couple to have twins based on genetics. In other words, twins on the father's side of the family will have no influence on your chances of having twins.
Vanishing twin syndrome is a condition in which one of two fetuses disappears sometime during the first 12 weeks of a pregnancy. Early in a multiple pregnancy, it is possible to miscarry one fetus and to notice some vaginal bleeding or to notice nothing unusual. Sometimes the embryo or fetus is reabsorbed by the body.
What are the signs of a twin pregnancy?
A selective termination of the acardiac twin reduces the risk of death of the pump twin. Selective reduction is used when a mother is carrying an unsafe or undesirable number of fetuses in a multiple pregnancy, which are common in medically assisted pregnancies.
Cryptic pregnancies are uncommon. Studies suggest about 1 in 475 pregnancies go unnoticed until about 20 weeks gestation. About 1 in 2,500 pregnancies go unnoticed until delivery.
Ultrasound detects 50–70 % of major anomalies in ideal settings, but many conditions—such as cardiac defects, skeletal dysplasias, orofacial defects ( Cleft lip, Cleft palate etc) and limb abnormalities—remain undiagnosed.
An ultrasound scan is the only sure way to find out whether you're having twins. Physical changes are more obvious in a twin pregnancy than a single pregnancy. Women with twin pregnancies are more likely to have pregnancy health problems and complications.
While some twins may share a placenta and an amniotic sac, that is not the case for the vast majority of pregnancies.
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 a Doppler.
Hidden twin on an ultrasound
Sometimes, one fetus can be hard to spot during early ultrasound scans, often because it is positioned behind its sibling. This is more common in twins who share the same amniotic sac, but it can happen with other types of twins too.
A twinless twin (surviving twin) who has lost a twin sibling before or shortly after birth due to miscarriage, vanishing twin syndrome, stillbirth, or due to medical complications may not have conscious memory of their twin but may sense something missing from their lives even if they were not informed they were indeed ...
As of June 2020, NIPT has also been available for dichorionic twin pregnancies, multiple pregnancies and vanishing-twin pregnancies.