Vanishing Twin Syndrome
Vanishing Twin Syndrome
In 1945, Walter Stoeckel proposed that the general population of conceptions were higher for multiple fetuses that supposed, suggesting that a twin or multiple fetuses may die in utero and subsequently be reabsorbed without clinical evidence by the surviving fetus/es, mother, or placenta (Stoeckel, 1945, cited in Levi, 1976). Named the “vanishing twin syndrome”, the cause is generally not known. If abnormalities are determined, they appear related to early development and are chromosomal; improper implantation of the cord may also play a role.
This paper presents a brief overview of the etiology, demographics, consequences, and tests for the anomaly in addition to the presentation of a documented case study.
Vanishing Twin Syndrome versus Parasitic Twin Syndrome
There is sometimes confusion between the presentation of an infant that is a parasitic twin and one where there is a vanishing twin because the prenatal processes are the same. Parasitic twins share the same uterus, are monozygotic, and do not separate during crucial stages
East Indian boy with parasitic twin that blinked, smiled, blew bubbles, and cried. Child died from postoperative infection in an attempt to remove the twin (Anatomy Box.com, 2016)
of development. The only outcomes that result in a viable child if the head of the dependent sibling is not removed. In the vanishing twin phenomenon, there may be two separate gestational sacs. There are some other distinct differences in the two syndromes. First, vanishing twins may be of different genders whereas parasitic twins are always the same gender. Second, parasitic twins are co-joined with one or both of them surviving after birth. A viable infant with a twin that is considered “vanished” is the only child birthed, but a tumor with partial pieces of the deceased twin may appear with no discernable limbs or other body parts.
With the invention of ultrasound visualization, vanishing twin syndrome may be verified earlier than birth, when placental examination was the method of diagnosis. Sonography in the first term of pregnancy confirms that “vanishing twin” syndrome occurs fairly frequently; it is estimated that the vanishing twin syndrome presents in 21 percent to 30 percent of pregnancies
Figure 2. Ultrasound demonstrating vanishing twin; not related to case study ("Vanishing Twins", 2016)
with more than one fetus. Clinical presentation for the mother usually occurs in the beginning of the pregnancy and includes complaints of pelvic pain, cramping, and bleeding. More cases appear with maternal age over 30 years. However, if the decreased fetus dies after the first trimester, the pregnancy is considered to be high-risk. A tumor in the surviving child may contain tissue, hair, bone, or teeth.
A nuchal translucency test requires only 8 percent of fetal DNA to diagnose a confounding factor for non-invasive prenatal testing NIPT (Grömminger et al., 2014).
Consequences of Vanishing Twin Syndrome.
Fetus papyraceus. If the fetus dies after the embryo has begun to develop, tissue fluid and tissue from the placenta may be absorbed; if gestational age allows, amniotic fluid may also be absorbed. The deceased twin then becomes flattened by the growth of the remaining child. The presence of fetus papyraceus may promote the presence of aplasia cutis congenital in the surviving child.
Cerebral palsy, If the deceased fetus dies within the first trimester, there is little or no significant effect on the remaining infant and the mother. However, if the fetus dies later in the pregnancy, there is a possibility of increased risk of cerebral palsy; Pharoah and Adi (2000) estimate a 14 percent higher risk of the surviving child in vanishing twin syndrome to demonstrate the symptoms of the disease. The researchers studied 434 cases of vanishing twin syndrome in England between 1993 and 1995. Five of the viable births died within a one-year period secondary to a diagnosis of cerebral palsy. Of the 241 children followed after birth, 23 suffered from cerebral palsy and another 28 had other forms of impaired cerebral function. The prevalence from the study concluded that that there was a 106 chance per 1000 births for cerebral palsy and 114 per 1000 births for cerebral impairment when vanishing child syndrome was determined, an overall risk of approximately 20 percent.
Aplasia cutis congenital. Frieden (1986) recognized aplasia cutis congenital (ACC) as a rare birth defect diagnosed by absence of skin. He classified the disorder into nine categories with ACC with fetus papyraceus as the fifth type. There is a butterfly or stellate pattern with involvement of the trunk, thighs, and buttocks. Rather than skin, there is a shiny, telandiectasious membrane. It is believed the condition results when the fetus papyraceus releases thromboplastin into the placenta after death, causing cutaneous infarction. The surviving twin also looses skin secondary to hypovolemia and hypotension. Differential diagnosis is based on histopathology reports and absence of the top or deeper layers of the skin. While there is no intrauterine treatment, preparation of the parents and planning for postnatal care is required. Treatment involves topical antibiotics, an acellular dermal regeneration
Figure 1. Newborn female (8 hours) with symmetrical, stellate type of truncal aplasia cutis congenital; surviving child of vanishing twin that died at gestaional age of 13 weeks and 5 days (Meena, Saxena, Sinha, & Dixit, 2015)
template such as Integra, allografts such as Epifax (a dehydrated human amnion/chorion membrance product), and paraffin dressings that will not adhere to the surface (Moss & Shahidulla, 2010). The lesions usually heal with unpigmented margins and scarring.
Parental distress. While there is at least one viable child, the knowledge that another fetus died in utero may well be upsetting for the parents. Support groups and counseling should be recommended.
A case study reported by Grömminger et al. (2014) involved a couple undergoing infertility treatment; the mother was 39 years of age. Two artificially inseminated embryos were implanted and two gestational sacs and heartbeats were confirmed. At gestational age of 10 weeks, a routine ultrasound failed to detect one of the heartbeats. A nuchal translucency test showed a normal measurement for the living twin of 2.5mm and of 3.1 mm for the deceased twin. The deceased fetus was still seen in an ultrasound scan at 17 + 2 weeks gestation. Due to advanced maternal age, a routine NIPT was performed, indicating a z-score of 13.5, positive for trisomy 21. An amniocentesis showed the viable fetus has a karyotype of 46, XY which was comparable to the NIPT test results, confirming trisomy 21. In the third trimester, blood testing showed negative for trisomy 21. Following the birth of the child, a fetus papyraceus was found in the placenta tissue which tested positive for trisomy 21 and the female karyotype of 47, XX, +21 was found. Blood testing of the viable infant and the mother were phenotypically normal with no evidence for either having the genetic mosaicism required for trisomy 21. The conclusion was that the vanishing twin was responsible for the trisomy 21 test result.
Conclusion
The primary method of diagnosis is the use of sonographic visualization. The confirmation of a placenta and fetal heartbeat in the first trimester following by subsequent absence allows health care professionals to undertake additional testing to formulate a diagnosis. Amniocentesis may prove helpful in recognition of cause, but the primary consideration is attention to the remaining fetus and mother during the term of the pregnancy and postpartum period.
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