PREGNANCY-BIRTH Messages for January, 1999: Re: Vanishing Twin ?

Re: Vanishing Twin ?

From: D. Ashley Hill, M.D.

anonymous@obgyn.net

Thu, 28 Jan 1999 22:28:42 -0600 (CST)

Ann-

This is a tough one. I'll try to post a coherent response. I sat down with a pen and calculated that the reason I'm so tired tonight is that I've worked 102 hours this week. My wife is surprising me with a trip to New Orleans for the weekend (o.k., so I accidentally found out), so I'm taking a break from packing.

Nobody is sure why some patients have a "vanishing" twin pregnancy, but there are many possibilities. Twin pregnancies are by nature high risk. Many patients want them, but few ob/gyn doctors would agree that twins are as "cool" as most folks think they are. There is a higher incidence of miscarriage, stillbirth, preterm delivery, preeclampsia (toxemia), diabetes, c/section, and postpartum hermorrhage. In the case of a vanishing twin, the placenta may be too small to support two fetuses, or one fetus might have a chromosomal anomaly that is incompatible with life. I can't answer whether so-called "identical" twins both share the exact same chromosomal anomalies, but I would doubt this is necessarily true.

Part of the problem I have here is that I'm not sure whether you had a vaginal ultrasound, which is best, or an abdominal one. If it was vaginal, and *if* the sonographer or doctor knew what he or she was doing and got good measurements, then I'm sorry to say it is likely that one fetus is not going to make it. Of course, those are big if's, and it's possible that the measurements were off. Unless this is an extremely rare situation where you had two eggs fertilized a week apart, or the even more unusual situation that has been reported a few times where there are two fathers, and thus two different intercourse events, and two very different "twin" pregnancies, the the most likely situation is that the smaller twin will not survive. The larger twin likely has a heart beat (I don't think you said whether it did or not). To answer your question, 99.9 percent of the time, twin pregnancies progress at almost exactly the same rate.

I hope I'm wrong. If not, then please be reassured that most patients I have cared for with this situation do fine, and the remaining baby grows normally. Sometimes there is off and on bleeding but in my experience miscarriage of the surviving baby is unusual. I want to add one more thing: I have seen my share of "mommy guilt" when it comes to pregnancy problems. There is *nothing* you could have done that would lead to a vanishing twin situation. An old saying goes "nature is a bad obstetrician" and this is one example of the many bad luck things that can happen as we try to have kids.

Good luck with everything. I hope you receive the good news you are looking for in a few weeks.

Take care,

-- Ashley Hill David Ashley Hill, M.D. Associate Director Department of Obstetrics and Gynecology Florida Hospital Family Practice Residency Orlando, FL http://home.mpinet.net/dahmd

The above is intended for general medical education, and is not for specific medical advice. I apologize, but I am unable to answer personal e-mail due to time constraints.

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