Vanishing Twin Syndrome (VTS), Part 1

Vanishing Twin (VT): Frequently Asked Questions (FAQs)

To my surprise, the Vanishing Twin article is the most hit-on article on my Site. Due to very early ultrasounds (5 or 6 weeks) we learn early if we are pregnant and with how many. By about week 12, things can drastically change. Following are some FAQs on Vanishing Twin:


Q – How long will I continue to bleed?

Ans: Each woman is unique as is each pregnancy, even for the same woman.  Duration of bleeding can depend upon when VT occurred. For example if it occurred at 7 weeks, a woman may not bleed as long as if it occurred at 10 weeks. Some women don’t bleed at all and their body reabsorbs the VT tissue with no outward indication of the loss.

Q – Will the VT hurt the other baby (ies)?

Ans:  In the majority of cases, if the other baby(ies) is healthy, it(they) will be fine. Your doctor can confirm, through ultrasound and fetal monitoring, the health of your remaining baby(ies). Generally there will have be no difficulty as the pregnancy progresses through to a healthy birth.

Q – Will there be any evidence left at the birth of the survivor?

Ans: Usually at birth, there is little if anything left of the VT. There might be a “thickening” of a portion of the placenta.  It depends upon when the VT and the birth of the surviving baby occurred as to whether or not the VT is visible. For example: if say the VT occurred at 8 weeks and the birth of the survivor occurred at 39 weeks, there is little chance of any remaining physical evidence of a VT. If the VT occurred at 12 weeks and the survivor is born prematurely, say at 32 weeks, then there may be some evidence of VT or there may not.

Q – What caused the VT? What did I do wrong?

Ans: It isn’t fully understood why VT occurs but it can be surmised that an embryos did not properly attach to the uterine wall and therefore failed to receive adequate nutrition to grow and develop. As can be appreciated from the scenarios mentioned in Ques. No. 3, there can be little to study after birth in order to ascertain why a particular pregnancy failed to produce healthy multiples. Early ultrasounds (at 5 to 6 weeks), can indicate a woman is pregnant and with how many. Two decades or more ago, the first ultrasound occurred much later in a pregnancy, about 16 to 20 weeks, well past when a woman would have known that she was initially carrying two or more. As a result she would have no knowledge that she had been carrying more than one.  It is generally felt nowadays that many more of us begin life as twins than was previously thought. What can be assured is that VT isn’t anyone’s fault and neither parent did any thing wrong.

Q – How long will it take for the empty sac to be reabsorbed by the mother’s body?

Ans: Each case is unique and needs to be evaluated on an individual basis. Your doctor is the best person to advise you for your particular case.

With ultrasound, it is now possible to know as early as five or six weeks that you are pregnant. However, with these first trimester, early ultrasounds an interesting side effect has occurred. The early ultrasound confirms two or more fetuses and a subsequent ultrasound reveals the ‘disappearance’ of at least one of the fetuses and an empty sac may be visible. This ‘disappearance’ is called Vanishing Twin.Researchers now suspect that many more multiples are conceived than previously thought and unexplained bleeding early in the pregnancy may be the miscarriage of a multiple. In the past, women usually had their first ultrasound later in their pregnancy (after 12 weeks pregnant) and therefore would never have known that they were carrying multiples. Nowadays the use of early ultrasound (in some cases as early as five weeks pregnant) can confirm a multiple birth pregnancy, while a later ultrasound confirms the loss of one or more of the babies. While not all cases of vanishing twin are associated with bleeding, this may explain why some women experience some cramping, bleeding or passage of tissue early in their pregnancy, but nevertheless the pregnancy continues, is uncomplicated and culminates with the birth of a healthy child(ren).

Vanishing twin can also occur within higher order multiple sets. I made an initial contact for registration for multiple birth prenatal classes with a family 8-1/2 weeks pregnant with triplets. When they arrived for the first class at just over 13 weeks pregnant, they advised that a subsequent ultrasound had shown that they were now carrying two babies and an empty sac was visible on the ultrasound. This family had very sad feelings because two other families in the class were carrying triplets and they should have been part of that group.

It is not uncommon for families with vanishing twin to experience feelings of sadness, grief and loss as they had anticipated and looked forward to a multiple birth.

It is not clear why one (or more) fetus fails to develop and is either miscarried or reabsorbed into the mother’s system.

For additional information, please see Vanishing Twin Syndrome, Part 2

Some Resources on Vanishing Twin

Twins! Pregnancy, Birth and the First Year of Life, by Connie. L. Agnew, Alan H. Klein and Jill Alison Ganon, Harper Perennial
Multiple Blessings, by Betty Rothbart, Hearst Books
Double Duty, by Christina Baglivi Tinglof, Contemporary Books
Mothering Multiples, by Karen Kerkhoff Gromada, La Leche League International
The Art of Parenting Twins, Patricia Maxwell Malmstrom and Janet Poland, Ballantine Books


Please Note: I am unable to answer any medical questions. If you have any concerns regarding your medical situation, please check with your healthcare professional.

Additional information about ultrasounds and sonograms – particularly relating to diagnostics, exposure principles, and the role of an ultrasound technician – can be found through a variety of medical resources.

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