Vanishing twin

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**Vanishing twin**
*Classification & external resources*
ICD-10	O 31.2
ICD-9	651.33
DiseasesDB	31893
eMedicine	med/3411

A vanishing twin is a fetus in a multi-gestation pregnancy which dies in utero and is then partially or completely reabsorbed by the mother. (Landy, 1986) Occasionally, rather than being completely resorbed, the dead fetus will undergo mechanical compression by its wombmate(s), resulting in a flattened, parchment-like state known as fetus papyraceus. (Pelega,1988) If the fetus is absorbed completely, there are usually no further complications to the pregnancy, other than first trimester vaginal bleeding. (Saidi, 1988) However, if the event occurs in the second or third trimester, serious complications may include premature labor, infection due to the demise of the fetus, and hemorrhage. Even at the end of the pregnancy, a low-lying fetus papyraceus may block the cervix and require a cesarean to deliver the living twin.

According to Charles Boklage, who is a professor in the Department of Pediatrics in the Brody School of Medicine and adjunct professor of biology at East Carolina University, vanishing twins occur in up to one out of every eight pregnancies (Bocklage,1995) and may not even be known in most cases. Since it is hypothesized that in some instances vanishing twins leave no detectable trace at birth or before, it is impossible to say for certain how frequent the phenomenon is. However, it has been hypothesized for a long time that non-righthanded and left-handed individuals may be the survivors of "mirror image" identical twinning (Newman, 1928) but recent research does not seem to support that view. (Medland, 2003)

The occurrence of this phenomenon is sometimes referred to as twin embolisation syndrome or vanishing twin syndrome (VTS).

"Vanishing" twins are frequently encountered in pregnancies created as a result of IVF. Ultrasound scans are taken very early in these pregnancies,ie. 5-8 weeks, so that where a multiple conception has occurred, it frequently happens that more than one amniotic sac can be seen in early pregnancy whereas a few weeks later there is only one to be seen and the other has "vanished". (Jauniaux, E, et al.1988)

The vanishing twin syndrome has been cited by biotech company Acu-Gen as an ad hoc hypothesis to explain false results of the company's Baby Gender Mentor test. According to the company, on occasions where their pregnancy gender test has apparently given the incorrect gender of the fetus, the apparent mistake can be explained by a fetus having been present at the time of testing, but later being reabsorbed as a vanished twin. According to the company's critics, this excuse does not seem plausible.

It has been speculated that the children born in such a pregnancy may have some memories of their vanished twins, and may feel lonely because of this. (Hayton. 2007) There is no scientific evidence to support this claim. Researchers of the paranormal, such as George Noory's talkshow Coast to Coast, have discussed the alleged phenomenon.

A wombtwin is a term used since 2003 to describe an embryo or fetus that was a member of a twin pair or triplet set and which died in the womb. The loss of a twin very early in pregnancy has been called "vanishing twin" phenomenon since the 1980s when twin pregnancies were made visible by means of ultrasound (sonograph) scanning. Two developing gestational sacs are seen at the first ultrasound scan but only one is visible at the second scan. The wombtwin dies owing to a poorly implanted placenta; a developmental anomaly that may cause major organs to fail or be missing completely; there may be a chromosome abnormality incompatible with life. Frequently the twin is a blighted ovum, that never developed beyond the very earliest stages of embryogenesis.

INDICATORS OF A POSSIBLE LOST TWIN: (Hayton,2007)

1.Drugs to stimulate ovulation 2.Extra large around the waist in first trimester of pregnancy 3.Vaginal bleeding in the first trimester 4.Ultrasoundimages of a vanishing twin 5.Trauma in pregnancy such as an accident, an infection, surgical treatment or extreme emotional stress. 6.A breech birth 7.An unusual placenta - ie, double / extra large/ extra thick or fragmented 8.Attachments to placenta such as additional umbilical cords or amniotic sacs 9.The fetus papyraceous 10.Fetus in fetu 11.Teratoma 12 Mirrored organs/left-handednessa surviving "mirror" twin 13.Split organs, additional bones 14.Uncertain sexuality or gender confusion 15.Genetic chimera 16.Cerebral palsy 17.Congenital anomalies

[edit] See also

[edit] References

Boklage, C.E.,(1995)The frequency and survivability of natural twin conceptions, in Keith, L.G., Papiernik, E., Keith, D.M. and Luke, B. (eds) Multiple Pregnancy: Epidemiology, Gestation and Perinatal Outcome. New York: Parthenon. Chapter 4 pp. 41-2, 49

Hayton A. (ed) (2007) Untwinned; perspectives on the death of a twin before birth, Wren Publications, 0952565498

Jauniaux, E, et al. (1988) Clinical and morphologic aspects of the vanishing twin phenomenon Obstetrics & Gynecology 72:577-581

Landy HJ, et al. (1986) The "vanishing twin": ultrasonographic assessment of fetal disappearance in the first trimester. Am J Obstet Gynecol. Jul;155(1):14-9.

Landy, H.J.and L.G.Keith (1998)The vanishing twin: a review Human Reproduction Update Vol. 4, No. 2 pp. 177

Medland, Sarah E. et al. (2003) Special Twin Environments, Genetic Influences and their Effects on the Handedness of Twins and their Siblings Twin Research, Volume 6, Number 2, 1 April 2003, pp. 119-130(12)

H. H. Newman (1928) Studies Of Human Twins II. Asymmetry Reversal, of Mirror Imaging in Identical Twins Biol. Bull 55:October Pp. 298-315.

Pelega, D. et al.(1988) Single intrauterine fetal death (fetus papyraceus) due to uterine trauma in a twin pregnancy European Journal of Obstetrics & Gynecology and Reproductive Biology Volume 80, Issue 2 , October, p. 175-176

Pharoah P. O. D, Price T S, and Plomin R (2002) Cerebral palsy in twins: a national study. Archives of Disease in Childhood Fetal and Neonatal Edition 87:F122-

Pharoah, Peter O.D (2005) Causal Hypothesis for Some Congenital Anomalies Twin Research and Human Genetics, Volume 8, Number 6, December, pp. 543-550

Saidi M.H. (1988) First-trimester bleeding and the vanishing twin. A report of three cases. J Reprod Med. Oct;33(10):831-4.