The epidemiology of conjoined twins in Latin America

Early unexpected diagnosis of fetal life-limiting malformation; antenatal palliative care and parental decision

INTRODUCTION

Conjoined twins are an infrequent occurrence in obstetric practice. Live-conjoined twins on a late preterm triplet pregnancy is an even rarer event.

OBJECTIVE

The objective of this study is to emphasize the critical importance of perinatal palliative care and non-directive parental counseling, informed decision making and respect for autonomy following full disclosure of findings, fetal life-limiting diagnosis, treatment alternatives, maternal-fetal potential complications, and most likely perinatal outcomes.

METHODS

Early surprise prenatal diagnosis, comprehensive parental counseling, palliative care, and perinatal care of a set of conjoined twins and a singleton.

RESULTS

Cesarean delivery of a set of conjoined twins and a singleton at 34 weeks' gestation. Immediate neonatal death of the conjoined twins, intact survival, and discharge of the singleton. Review of the database on previously reported similar cases. It is very important to utilize simple and direct language for parents to understand the grave prognosis to the pregnancy. Care alternatives in view of the maternal physical risks and psychological impact of carrying a high order abnormal multiple pregnancy, along with the possible side effects on the singleton.

Dicephalus dipus dibrachius twins: report of an autopsy case

Dicephalus dipus dibrachius twins are a rare form of conjoined twins. An autopsy of conjoined dicephalus twins is reported. The diagnosis was performed during the pregnancy and the family received a judicial authorization for termination of pregnancy. The preterm newborn progressed to cardiac arrest and died following a court order to terminate the pregnancy. The conceptus presented two arms, two legs, a trunk, two heads, and a single umbilical cord. The two spinal columns presented vertebral fusion in the sacral region. The heart exhibited complex malformations. The external genitalia were female; and cytogenetic analysis confirmed female sex (46, XX). This analysis also corroborated the etiopathogenic hypotheses described for this abnormality, which proposes failures in embryonic formation rather than specific chromosomal alterations. Current identification of cases by ultrasound permits medical management and multidisciplinary action with the family, enabling the legal termination of pregnancy.

Siamese Twins With Craniofacial Duplication and Bilateral Cleft Lip/Palate in a Ceramic Representation of the Chimú Culture (Peru): A Comparative Analysis With a Current Case

Craniofacial duplication or diprosopus is a very rare malformation that is present in approximately 0.4% of conjoined twins. Here is presented a case of craniofacial duplication in association with bilateral cleft lip/palate in both heads found in a ceramic representation from the early Chimú culture from Peru. A comparative analysis is made with a current case of a 28-week-old fetus with similar characteristics. After reviewing the medical literature on conjoined twins, very few reports of facial cleft in both twins were found, with no reports at all of bilateral cleft lip/palate. This ceramic crock is considered one of the first representations suggestive of craniofacial duplication, and probably the first reporting it in association with facial cleft.

Conjoined twins and legal authorization for abortion

OBJECTIVE

To describe pregnancies with conjoined twins according to the request for legal termination of pregnancy.

METHODS

Retrospective review of pregnancies with conjoined twins, with no possibility of extrauterine survival or postnatal surgical separation, observed at a tertiary teaching hospital, between 1998 and 2010.

RESULTS

Amongst 30 cases seen during the study period, six (20.0%) couples decided to continue with the pregnancy, termination of pregnancy was not requested due to advanced gestational age (> 25 weeks) in 5 cases (16.7%). Legal authorization to terminate the pregnancy was requested in 19 (63.3%) cases: permission was granted in 12 (63.2%), denied in five (26.3%) and information was missing in two (10.5%) cases. A successful vaginal delivery was performed in 83.3% of the cases undergoing termination of pregnancy and a cesarean section was performed in all the remaining cases (p < 0.01).

CONCLUSION

In pregnancies with conjoined twins and without fetal prognosis, legal termination of the pregnancy is an alternative. Moreover, a successful vaginal delivery can be performed in most cases before the third trimester, further reducing maternal risks and parental suffering.

Conjoined twins: a worldwide collaborative epidemiological study of the International Clearinghouse for Birth Defects Surveillance and Research

Conjoined twins (CT) are a very rare developmental accident of uncertain etiology. Prevalence has been previously estimated to be 1 in 50,000 to 1 in 100,000 births. The process by which monozygotic twins do not fully separate but form CT is not well understood. The purpose of the present study was to analyze diverse epidemiological aspects of CT, including the different variables listed in the Introduction Section of this issue of the Journal. The study was made possible using the International Clearinghouse for Birth Defects Surveillance and Research (ICBDSR) structure. This multicenter worldwide research includes the largest sample of CT ever studied. A total of 383 carefully reviewed sets of CT obtained from 26,138,837 births reported by 21 Clearinghouse Surveillance Programs (SP) were included in the analysis. Total prevalence was 1.47 per 100,000 births (95% CI: 1.32-1.62). Salient findings including an evident variation in prevalence among SPs: a marked variation in the type of pregnancy outcome, a similarity in the proportion of CT types among programs: a significant female predominance in CT: particularly of the thoracopagus type and a significant male predominance in parapagus and parasitic types: significant differences in prevalence by ethnicity and an apparent increasing prevalence trend in South American countries. No genetic, environmental or demographic significant associated factors were identified. Further work in epidemiology and molecular research is necessary to understand the etiology and pathogenesis involved in the development of this fascinating phenomenon of nature.

[Cephalopagus conjoined twins: case report and review of literature]

Cephalopagus are a rare variant of conjoined twins resulting from an incomplete late division of the embryonic disk and associated with an extremely poor fetal prognosis. Here, we report a rare case of a male cepahalopagus conjoined twins diagnosed during the 23rd week of gestation. Delivery was vaginal showing twins fused from the top of the head to the umbilicus. The fused skull showed a cephalocele with agenetic brain. Esophagus, stomach and duodenum are common for the two twins. Causes, diagnosis and management of cephalopagus are discussed referring to literature.

Di-symmetric cephalopagus conjoined twins described by Hovorakova et al.: some additions and corrections

This article provides some additions and corrections on a recently published case report concerning a pair of di-symmetrical cephalopagus conjoined twins. Eight different types of conjoined twins can be distinguished; one is cephalopagus, which is fourth in rarity of occurrence. Between 17 and 24% of cephalopagus is of the male sex. More than 30 case reports of di-symmetrical cephalopagus can be traced in Western literature, the oldest one described and illustrated in 1569.

Epidemiological and clinical analysis of a consecutive series of conjoined twins in Spain

PURPOSE

The aim of the study was to analyze the frequency and certain epidemiological characteristics of a consecutive series of conjoined twins born in Spain.

MATERIAL AND METHODS

We used data from the Spanish Collaborative Study of Congenital Malformations for the period April 1976 to 2006. Because the Spanish law permitting voluntary termination of pregnancies (TOP) when the fetus presented malformations was effective by the end of 1985, we analyzed the data in 4 periods, 2 before 1986 and 2 after. During the first period (1976-1979) only live births were recorded, whereas both still and live births were included in the other three (1980-1985, 1986-1995, and 1996-2006). In the present study, the cases were classified as symmetrical (16 pairs) and asymmetrical (1 pair) conjoined twins. Each pair of conjoined twins was considered as only one case for calculations, regardless of the type of union.

RESULTS

Among a total of 2,281,604 consecutive births between 1980 and 2006, there were a total of 15 cases of symmetrical conjoined twins giving a frequency of 0.70 per 100,000 (1/152,107), whereas there was only 1 stillborn asymmetrical conjoined twin pair (0.04/100,000). Among the 13,418 consecutive stillborns surveyed, 6 cases of conjoined twins were identified (either symmetrical or asymmetrical) giving a frequency of 44.72 per 100,000, and 11 pairs were identified among the 2,425,583 total live births surveyed during the first period 1976 to 1979, a frequency of 0.45 per 100,000. Thus, the frequency among stillborn infants is 99.34 times higher than that observed among live births. However, the frequency for the total births (3 last periods) showed a decreasing trend from 1.47 per 100,000 birth in the first period (1980-1985) when TOP was illegal, to a value of 0.09 per 100,000 in the last period, more than 16-fold lower, probably because of the TOP of affected fetuses. Therefore, we consider that the frequencies observed in the period 1980 to 1985 are the basal values in our population. The most frequent type observed was thoracopagus, with an overall prevalence at birth of 0.44 per 100,000 (1/228,160) from 1980 to 2006, representing 58.82% of the total population of symmetric conjoined twin pairs. Diprosopus pairs were the next most common group (11.76%). Most of the cases were females (4 males/11 females), and although this appeared to be mainly because of the thoracopagus pairs (males-females, 2:8), in such a small number of cases, it is not possible to determine the ratios for the other groups. Gestational age was significantly shorter than in control twins for each type studied.

CONCLUSIONS

We conclude that it is incorrect to consider that all types of conjoined twins have the same epidemiological characteristics, such as the frequency at birth. The differences observed may be related with the distinct embryo-fetal mortality of each type of conjoined twins in different populations, and the sex ratio, among others.

Sirenomelia and cyclopia cluster in Cali, Colombia

Sirenomelia and cyclopia share etiologic and pathogenic characteristics. A cluster of these two patterns of malformation in the city of Cali, Colombia, is described. Four sirenomelia and four cyclopia cases were born within a 165 days period in one hospital in Cali. The lapse between conception dates of first and last cases was shorter for sirenomelia (53 days) than for cyclopia (231 days). Based on ECLAMC (Latin American Collaborative Study of Congenital Malformations) published data, the observed/expected ratio (5.7) for both defects is statistically significant (P < 0.001). Mother's residence during the first trimester of pregnancy is concentrated in a same city quarter for four of the eight cases, close to a know polluting active landfill, and the other four cases, along the Cauca river, downstream from this landfill. Birth prevalence rates for two sentinel anomalies, that is, anal and esophageal atresia for sirenomelia and oral clefts for DeMyer holoprosencephaly spectra, were not higher in Cali than in the rest of ECLAMC material. The Computer Assisted Telephone Interviewing was applied to mothers of the 8 patients, and 32 matched controls. Seven of 295 variables were associated with sirenomelia, 3 of them related to house tap water, one to exposure to street drugs, one to physical injury, and 2 secondary to abnormal pregnancy outcome. None was associated with cyclopia. Results from hair dosage of heavy metals in the 8 patient's mothers were inconsistent. The time-space cluster is nonrandom for sirenomelia, and possibly random for cyclopia. The polluting landfill remains as a possible etiological factor.

Vaginal Delivery of Dicephalic Parapagus Conjoined Twins: Case Report and Literature Review

After an unsuccessful midwife-assisted delivery in which a head was born but delivery could not be advanced, episiotomy performed at Sanliurfa Maternity Hospital allowed vaginal delivery of female conjoined twins. Visual and x-ray examination showed two heads, two vertebral columns, two feet, two arms, and fusion at the level of the pelvis. The baby was born dead, but the mother made an uneventful recovery. Parapagus (anterolaterally joined) dicephalus (two-headed) twins account for only 11-13% of all conjoined twins, and they rarely survive. Complex malformations of hearts, lungs and abdominal organs, duplication of the tracheae, upper gastrointestinal tract and spinal column, and either double or single versions of other organs have been reported in parapagus dicephalus cases. The incidence, anatomical, embryological, diagnostic, prognostic, obstetrical, perinatal, and ethical aspects of conjoined twins are reviewed, with a focus on parapagus dicephalus conjoined twins.

Conjoined twins in a triplet pregnancy: early prenatal diagnosis with three-dimensional ultrasound and review of the literature

We report two cases of conjoined twins complicating a triplet pregnancy diagnosed by two-dimensional ultrasound in the first trimester and evaluated further by three-dimensional ultrasound. A review of the literature over the last 30 years revealed 11 other cases diagnosed prenatally by ultrasound. Overall, three (23%) of these 13 pregnancies were achieved by assisted reproductive techniques and 10 (77%) were diagnosed before 18 weeks. Four women opted for termination of the whole pregnancy and three were managed expectantly, with two delivering before 32 weeks. Two monochorionic pregnancies underwent selective feticide with intrauterine demise of the non-conjoined fetus in both cases. All four dichorionic pregnancies undergoing selective termination or spontaneous embryo reduction to singleton in the first trimester resulted in term delivery of the non-conjoined fetus. The rare condition of conjoined twins in a triplet pregnancy poses a significant obstetric challenge from both diagnostic and management points of view. Accurate determination of chorionicity in these cases plays a critical role in determining management and outcome.

Spectrum of anorectal anomalies in pygopagus twins

BACKGROUND/PURPOSE

The literature lacks a concise description of the anorectal anomalies encountered in pygopagus twins.

METHODS

This is a retrospective literature review of 34 pygopagus twins highlighting their anorectal malformations.

RESULTS

Overall pygopagus twins represent 17% of all conjoined twins. Live-birth pygopagus twins are more commonly female (86%), whereas stillborns are commonly male (80%). Half of the twins had nonfused rectums, and half had fused rectums. The nonfused had 2 rectums (80%) or one rectum and one rectovaginal fistula (20%). The fused had high (46%) or low (54%) rectal junctions. All reported living male pygopagus twins have had nonfused rectums. All can be managed applying the principles of posterior sagittal anorectoplasty.

CONCLUSIONS

In general, live-born male pygopagus twins are likely to survive with a nonfused rectum and good bowel function, whereas live-born female pygopagus twins have a good chance of surviving with a fused rectum (high or low), which requires appropriate operative reconstruction.

The Ibadan conjoined twins: a report of omphalopagus twins and a review of cases reported in Nigeria over 60 years

An omphalopagus set of female conjoined twins, undiagnosed prenatally, who presented as obstructed labour needing operative delivery is reported. Their anatomic characteristics and clinical features, including overwhelming sepsis in twin II which forced early separation, and those which led to their demise are described. Twelve other cases reported in Nigeria over the past 60 years are reviewed with reference to the aetiology and epidemiology of conjoined twinning and the determinants of successful surgical separation.

Partial caudal duplication in a newborn associated with meningomyelocele and complex heart anomaly

BACKGROUND

Caudal duplication is a spectrum of rare congenital anomalies with a possible heterogeneous pathogenesis including incomplete separation of monovular twins.

METHODS

We report an autopsy case of a full-term infant with incomplete caudal duplication syndrome associated with multiple anomalies.

RESULTS

These anomalies included a duplicated penis; double urinary bladder with an attenuated tunica muscularis; duplication of lower bowel with two ilia, appendices and colons; colonic hypogangliosis and left imperforated anus associated with rectourethral fistula. Other anomalies consisted of sacral meningomyelocele, sacral duplication with hypoplastic left sacrum and pelvic bones, muscle atrophy and hypoplasia of the left lower extremity, abnormal lobation of liver with stomach entrapment, omphalocele, and right atrial isomerism syndrome. The complex pattern of anomalies suggests the possibility that partial caudal duplication might be part of the spectrum of conjoined twinning.

Diprosopus (partially duplicated head) associated with anencephaly: a case report

Craniofacial duplication (diprosopus) is a rare form of conjoined twin. A 16 year old mother with a twin pregnancy delivered one normally formed baby boy and one diprosopus male. The malformed baby was 33 weeks of gestation with a single trunk, normal limbs and various degrees of facial duplication. Of the following structures there were two of each: noses, eyes, ears (and one dimple), mouths, tongues and, with bilateral central cleft lips and cleft palates. This was associated with holoprosencephaly and craniorachischisis. Internal organs showed no duplication. There were multiple congenital anomalies including diaphragmatic hernia, small lungs, two lobes of the right lung, ventricular septal defect, small adrenal gland and small left kidney with short ureter. The body also had a short neck, small chest cavities and kyphosis. X-ray revealed duplication of the vertebral column. The case presented here represents a type II of diprosopia of Rating (1933) and is the least common type reported. We also reviewed 22 recently reported cases of diprosopus. In addition to facial duplication, anencephaly, neural tube defect and cardiac malformations represent the more common congenital abnormalities associated with diprosopus. The pathogenesis of diprosopus is not well understood. Factors that play a role in diprosopus are probably similar to those factors (genetic, environmental and abnormal placental circulation) which affect monozoygotic twins as observed in this case report. Early ultrasonography diagnosis of diprosopus permits one to consider a vaginal therapeutic abortion.

Emergency separation of conjoined twins

Female omphalopagus conjoined twins were successfully delivered vaginally and required emergency surgical separation shortly after birth for gastroschisis. Shared tissue included conjoined bowel; one twin also had a complex cloacal abnormality and patent urachus. A 2-year follow-up is presented. A review of the relevant literature confirms that this is the first example of gastroschisis conjoining omphalopagus twins.

Conjoined twins--an epidemiological study based on 312 cases. The International Clearinghouse for Birth Defects Monitoring Systems

Data on conjoined twins have been collected from 14 different malformation monitoring programs around the world. Among over 28 million births, 312 cases were identified. After considering underascertainment in one large program, the best estimate of the incidence based on the sum of induced abortions and births is 1.3 per 100,000 births. The distribution according to type of twinning, the sex distribution (39% males) and the stillbirth rate (47%) are presented. The presence of malformations not directly related to the area of fusion is discussed. In three women, thyroid disease was present and five women had been treated for infertility before conception.

Conjoined twins in Hungary, 1970-1986

The total prevalence of conjoined twins (birth + prenatally diagnosed) was 1:68,000 in the study of 1970-1986. Symmetrical cases (the so-called siamese twins) have an obvious predominance (92.3%). Associated major malformations occurred in 80% of conjoined twins and more than 1/5 were discordant. The surviving time of liveborn conjoined twin sets was not more than two days except in two surgically successfully separated pairs. The family study did not indicate a higher recurrence risk. The case group was compared to two control groups and it appeared that the periconceptional use of oral contraception and ovulation induction were mentioned more frequently in pregnancies resulting in conjoined twins.