Vanished Twins and Misdiagnosed Sex: A Case Report with Implications in Prenatal Counseling Using Noninvasive Cell-Free DNA Screening.

Cell-free DNA testing is a recently introduced method for screening pregnant women for fetal trisomy, which is associated with some common significant genetic diseases, as well as the sex of the fetus. The case described here demonstrates the connection between the ultrasound "vanishing twin" phenomenon and the misdiagnosis of prenatal sex using cell-free DNA testing.

The vanishing twin: a major determinant of infant outcome in IVF singleton births.

This article attempts to assess the frequency of vanishing twins in assisted reproductive and spontaneously conceived pregnancies, including in-vitro fertilization (IVF), and its impact on the live-born surviving twin.

Spontaneous antenatal resolution of canine hydrops fetalis diagnosed by ultrasound.

A previously unreported syndrome of transient mid-gestational hydrops fetalis identified by ultrasound was diagnosed in 16 litters of 16 different dogs between November 1999 and May 2002. During this study period, a total of 161 canine pregnancies were diagnosed by ultrasound. A 17th litter of eight fetuses developed similar ultrasonographic changes concurrently with maternal systemic mastocytosis and subsequently spontaneously aborted. No pups were born with clinical signs of hydrops fetalis. Fetal resorption in the affected litters was 7/95 (7.4 per cent) and 8/95 (8.4 per cent) aborted. Of the fetuses that survived to term, there were 7/88 (8 per cent) stillbirths. Neonatal mortality rate in the affected litters was 15 per cent (11/73) and the incidence of congenital abnormalities was 7/73 (9.6 per cent). Pugs were significantly (22.8 times) more likely to be affected than other breeds.

A case-control study of vanishing twin as a risk factor for cerebral palsy.

It has been hypothesized that cerebral palsy of unknown etiology is the result of the death of an unrecognized co-twin--a vanishing twin--in early gestation. We conducted a case-control study of vanishing twin as a risk factor for cerebral palsy of unknown etiology in women who had an obstetric ultrasound during pregnancy. Among mothers of cases, one of 86 had evidence of a vanishing twin on ultrasound, as compared to two of 381 control mothers (odds ratio [OR] 2.2, 95% confidence interval [CI] 0.2-24.8; p = 0.5). Bleeding in early pregnancy, which may indicate the loss of a co-twin, was reported by 14 case mothers and 46 control mothers (OR 1.6, 95% CI 0.8-3.0; p = 0.3). On the basis of results presented here, the vanishing twin syndrome is unlikely to account for a high proportion of cases of cerebral palsy, but there is insufficient statistical power to draw firm conclusions.

Dose-incidence relationships on the prenatal effects of gamma-radiation in mice.

The objective of this investigation was to evaluate dose-incidence relationships on the prenatal effects of gamma-radiation. Pregnant ICR mice were exposed on day 11.5 after conception, coincident with the most sensitive stage for the induction of major congenital malformations, with 0.5-4.0 Gy of gamma-radiations. The animals were sacrificed on day 18 of gestation and the fetuses were examined for mortality, growth retardation, change in head size and any other morphological abnormalities. With increasing radiation dose, incidence of small head, growth retarded fetuses, cleft palate, dilatation of cerebral ventricle and abnormalities of the extremities in live fetuses rose. The threshold doses of radiation that induced cleft palate and dilatation of cerebral ventricle, and abnormal extremities were between 1.0 and 2.0 Gy, and between 0.5 and 1.0 Gy, respectively.

Monitoring pregnancy in babirusa (Babyrousa babyrussa) with transabdominal ultrasonography.

This case report documents the application of transabdominal ultrasonography for detecting pregnancy and monitoring fetal development in an unanesthetized, unrestrained babirusa (Babyrousa babyrussa). A 4-yr-old multiparous female babirusa was trained to accept monitoring via transabdominal ultrasonography on a weekly basis postcoitus. Uterine changes associated with pregnancy were first detected at 30 days gestation. Three fetuses were first visualized on day 38, and two of the three fetuses were detectable until term. One fetus failed to develop and appeared to be resorbed between days 80 and 94 of the 161-day pregnancy. The growth of the remaining two fetuses was monitored via cranial measurements taken during the weekly scans throughout the pregnancy. By monitoring a subsequent pregnancy via ultrasound in the same female it was possible to confirm her tendency towards partial resorption, with earliest detection of uterine changes on day 32 and apparent resorption of one of three fetuses at approximately the midpoint of gestation. Two rectal scans of a different female under anesthesia at 28 and 50 days gestation showed stages of development comparable to those visualized transabdominally. However, the transabdominal scans produced better images of the reproductive tract, perhaps because of the close proximity of the pregnant uterus to the abdominal wall.

Unrearable litters and prenatal reduction of litter size in the common marmoset (Callithrix jacchus).

It is widely believed that common marmosets (Callithrx jacchus) typically give birth to twins under natural conditions. In captivity, however, births of triplets or even larger litters are common, although parents rarely succeed in rearing more than two offspring. The traditional interpretation is that captive conditions, notably the ready availability of food, have led to increased reproductive output, perhaps involving a higher ovulation rate. The present paper provides evidence, combined from ultrasound examinations between ovulation and birth and hysterotomies conducted during the late embryonic and early fetal phase, that the litter size can be progressively reduced during pregnancy without spontaneous abortion. There is an unusually long lag phase prior to the onset of embryonic growth in common marmosets; the fetal stage does not begin until day 80 of the 144-day pregnancy. Reduction in litter size occurs during embryonic stages (up to day 80), and continues into the fetal stages. These results indicate that the common marmoset is adapted for flexible modification of litter size between ovulation and birth. The high incidence of triplet births in captive colonies may therefore be an expression of an adapted natural developmental process under artificial circumstances.

Vanished twin and fetal alcohol syndrome in the surviving twin. A case report.

BACKGROUND: The diagnosis of twin pregnancy can be made early in pregnancy by ultrasonography (US). Follow-up examination occasionally demonstrates the disappearance of one of the twins. CASE: A twin disappeared on US examination; the surviving twin exhibited signs of fetal alcohol syndrome and other congenital anomalies, accompanied by a placental form of fetus papyraceus. CONCLUSION: Early US examination is useful for diagnosing multiple gestation. However, a follow-up examination is required to alert the clinician to the disappearance of one twin. Careful examination of the placenta may document fetal remnants. In this case a small, atretic nodule on the placental surface was evidence of the vanished twin.

Ultrasonographic assessment of abnormal pregnancy.

Ultrasonographic imaging is widely used in small animal practice for the diagnosis of pregnancy and the determination of fetal number. Ultrasonography can also be used to monitor abnormal pregnancies, for example, conceptuses that are poorly developed for their gestational age (and therefore are likely to fail), and pregnancies in which there is embryonic resorption or fetal abortion. An ultrasound examination may reveal fetal abnormalities and therefore alter the management of the pregnant bitch or queen prior to parturition. There are, however, a number of ultrasonographic features of normal pregnancies that may mimic disease, and these must be recognized.

[Abnormal twin pregnancy--early resorption of a single fetus in a twin pregnancy pregnancy]. / Abnormalna blizanacka trudnoca--rani gubitak jednog ploda iz blizanacke trudnoce.

INTRODUCTION: Twin pregnancy presents a condition of development of two fetuses in the uterus and can be monozygotic (single ovum) and dizygotic (two ova). In case of fertilization and segmentation of one ovum monozygotic twins are produced, while in case of fertilization of two ova, which can originate from one or two Graff follicles, dizygotic twins are developed. The ratio of twin and single pregnancies is 1:89 (according to Hellin's law) (1). The incidence of twin and other multiple pregnancies is influenced by: race of parents, age and parity of mother, use of clomid and gonadotrophin to stimulate ovulation, discontinued use of contraceptive pills and certain seasons (exposure to sunlight) (1). Due to occurrence of numerous complications twin pregnancy and parturition are considered to be highly risky. This is supported by clinical data on more frequent spontaneous abortions--especially in monozygotic pregnancies, hypertension in pregnancy, hemorrhage of various etiologies, anemias, early rupture of amniotic membranes, hydramnios, premature deliveries, etc. Nowadays diagnosis of both twin and other multiple pregnancies in the early stage is required, in order to establish normal or pathological development of such pregnancies. As early as 6 gestation week in twin pregnancies it is possible to sonographically visualize two gestation sacs in the uterus, while in 7-8 gestation weeks it is possible to see two embryos with evidence of fetal heart rate. In early pregnancy a differentially-diagnosed uterus may be clinically enlarged due to: hydratidaform mole, uterine mioma or ovarian cyst. In later gestation confirmation of twin pregnancy is possible by clinical and sonographic examination and biochemical analyses (elevated values of HPL and -fetoprotein) and less frequently, by x-ray. Repeated sonographic examinations can reveal the following anomalies of twin pregnancies: one normal pregnancy with one sac containing no embryo, one sac containing no embryo and one sac with a dead fetus, fetuses without vitality in both gestation sacs, two ultrasound echoes from which only one normal fetus and one dead mummified fetus (fetus papiraceus) result within the uterus. One gestation sac may be resorbed during pregnancy, while the undamaged fetus continues to develop normally in the uterus. In certain cases the loss of one fetus is not accompanied by any clinical symptoms, and in others this can be accompanied by light hemorrhage. An initial twin pregnancy after the loss of one twin may end by a birth of one healthy infant. CASE REPORT: A patient aged 35 years, came for gynecological examination due to missed menstruation. Ananmesis showed that she had a nascent uterine myoma which was removed by myomectomy six months earlier, had one parturition four years earlier, and no abortions. The last menstrual period was on February 12, 1991. Clinical examination showed a somewhat larger uterus than would be normal for amenorrhea of 9-gestation week. By sonographic examination two regular gestation sacs were found in the uterus with fetal echoes present as well as heart rate in both fetuses (Figure 1). Embryo measurements were as follows: Fetus 1-CRL-22.5 mm, NEG-8 + 4, heart rate present. Fetus 2-CRL-23.6 mm, NEG-9, heart rate present (Figure 2). The patient was cautiously informed that two fetuses are visible in the uterus and that this is a sign of twin pregnancy, but for certain diagnosis a control examination was scheduled two weeks later. The sonographic examination after 14 days later showed discord in fetal growth (Figure 3). Embryo measurement in 11-gestation week rendered the following parameters: Fetus 1-CRL-22.8 mm, NEG 8 + 6, no heart rate registered (Figure 4), while the second fetus continued to develop and had the following characteristics: Fetus 2-CRL-50.5 mm, NEG 11 + 4, heart rate and fetal movement registered (Figure 5). During entire pregnancy the patient suffered no pain or any kind of hemorrhage. She took no drugs. (ABST

The vanishing twin: a review.

This article reviews the scientific literature discussing the vanishing twin phenomenon. Information pertaining to frequency, aetiology, and potential complications, as well as the impact of sonographic technology on our growing understanding of the events in early multiple pregnancy is provided.

A hypothesis for the aetiology of spastic cerebral palsy--the vanishing twin.

The aetiology of spastic cerebral palsy (CP), in the majority of cases, is not known but the general consensus is that cerebral impairment occurs prepartum. In monochorionic twin pregnancies, death of one twin late in gestation is recognised as being an important risk factor for the surviving cotwin to have CP. It has been suggested that a significant proportion of singletons with spastic CP may be the result of death of a cotwin in the second half of gestation. In this paper it is hypothesised that spastic CP of unknown aetiology is the result of the death of a monochorionic cotwin and that the death of the cotwin may impair the neurological development of the survivor throughout gestation. If so, vanishing-twin syndrome, which is now a recognised phenomenon revealed by ultrasound examination in early pregnancy, is important in the aetiology of spastic CP.

Patterns of prenatal survival in the common marmoset (Callithrix jacchus).

Fifty common marmoset pregnancies were monitored using ultrasound. The objective was to ascertain if fetal mortality was related to litter size. Prior to analysis we determined abortion rate and litter size were not influenced by repeated ultrasound. Mortality was unrelated to litter size and occurred fairly late in gestation. All singletons born in this study began gestation as twins. It is hypothesized that marmosets may be able to adjust litter size late in pregnancy in response to proximate environmental factors.

Spontaneous fetal reduction in multiple gestations assessed by transvaginal ultrasound.

OBJECTIVE: To assess the occurrence of disappearance of one or more of the fetuses in pregnancies which start as multiple gestation. DESIGN: Observational study. SETTING: Infertility section, Rambam Hospital, Haifa. SUBJECTS: 88 women with multiple gestations, established after ovulation induction (54 twin, 26 triplet, five quadruplet, and three quintuplet) and diagnosed by transvaginal ultrasound at 5-6 weeks, in all of whom absorption of at least one gestation sac was detected at follow-up ultrasound scan. INTERVENTIONS: Follow-up by serial transvaginal and later abdominal ultrasound scan throughout pregnancy. RESULTS: Of the 54 twin gestations, 51 ended in the birth of a singleton and three in miscarriage. Of the 26 pregnancies starting as triplets, 12 ended in singleton births, 12 in twins and two miscarried. The five quadruplet gestations resulted in one singleton birth, one set of twins, two triplets, and one ended in late miscarriage. Of the three quintuplet pregnancies, two resulted in the birth of triplets, one of them after spontaneous, the other after iatrogenic fetal reduction. In the third quintuplet pregnancy, one fetus vanished spontaneously and another was subject to iatrogenic reduction, two fetuses survived and were liveborn. Of the 221 fetuses identified 107 (48%) vanished spontaneously. CONCLUSION: Iatrogenic fetal reduction should be delayed until 12 weeks gestation in quadruplet or higher multiple gestations, but is probably not indicated in twin and triplet gestations.

[Placental findings in "vanishing twins"]. / Plazentabefunde bei "Vanishing Twins".

We examined morphologically the placenta in 15 cases of a "vanishing-twin" phenomenon of early pregnancy sonographically confirmed. In 10 of these cases remnants of an additional gestation product could be identified with ample variation in their conservation. These ranged between macerated, but clearly identifiable foetal residues and morphologically regular, empty gestational sacs, all being localised at the placental margin or within the amniotic tissue sheets. The chorionic villi of the surviving twins were normally developed. There was no evidence of any correlation between the developmental status of the vanished twin and any therapeutical intervention, age of the mother or number of initial gestational products. In 3 cases, an intrauterine foetal reduction by foetocide had been performed. In these instances, rather well-developed remnants of the additional fetuses could be found. Since in all cases a pluri-chorionic placenta was present, it is possible, that the vanishing twin phenomenon may be held responsible for an eventual blood group incompatibility during subsequent pregnancies.

Human chorionic gonadotropin rise in normal and vanishing twin pregnancies.

OBJECTIVE: The purpose of the study was to describe and to compare the rate of rise of human chorionic gonadotropin (hCG) in vanishing twin and normally progressing twin pregnancies during the first trimester. DESIGN: All patients with twin pregnancies between 1985 and 1989 were prospectively studied. Human chorionic gonadotropin was measured one to three times per week between days 12 and 52 after luteinizing hormone (LH) surge or day of hCG administration (day 0). Pelvic ultrasound (US) was performed weekly beginning on day 24. SETTING: The study was performed at Rush-Presbyterian-St. Luke's Medical Center in an academic private practice setting of the Section of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology. PATIENTS: Forty patients who conceived after treatment of infertility and who had two gestational sacs on US examination were included in the study after the following criteria were met: (1) both sacs progressed to exhibit a fetal pole and (2) day of LH surge and/or day of hCG administration was known. MAIN OUTCOME MEASURE: The rate of rise of hCG was slower in vanishing twin pregnancies than in normally progressing twin gestations for the entire time period studied (P less than 0.05). RESULTS: A vanishing twin occurred in one third of the twin pregnancies. Forty-six percent of these losses occurred after fetal heart activity had been established. CONCLUSIONS: Vanishing twin phenomenon occurred in a large proportion of twin pregnancies in this infertility population. Fetal heart activity was not a reliable predictor of continuing fetal viability in early twin gestations. Vanishing twin conceptions were characterized by a slower rate of rise of hCG than normally progressing twin pregnancies.

The vanishing twin: morphologic and cytogenetic evaluation of an ultrasonographic phenomenon.

Twin pregnancy was observed by ultrasonographic examination in the 6th week of gestation. After singleton term delivery a thickening of the membranes opposite to the main placenta showed degenerated chorionic villi embedded between one layer of amnion and chorion; no fetal parts were observed. Villus cells from both placentas were mainly diploid; 2 of 30 were tetraploid. However, 19 of 30 cells from membranes overlying the satellite placenta were tetraploid. Marker analysis was consistent with duplication of a normal conception diploid chromosome complement as the mechanism for tetraploidy. Postconceptional nondisjunction leading to tetraploidy in one twin conceptus may explain demise in early pregnancy. Tetraploidy observed by chorionic villus biopsy must be confirmed by amniocentesis before interruption of the pregnancy is considered.