Two is a Crowd: Two is a Crowd: On the Enigmatic Etiopathogenesis of Conjoined Twinning

Parasitic pygopagus conjoined twins' incidental findings in the obstructed labor of an intrapartum dead baby that had undergone emergency C-section: rare case report in South Papua

BACKGROUND

Conjoined twins (CT), which used to be historically defined as "monstrous human" and previously so-called Siamese twins in the early eighteenth century, are one of the very rare congenital malformations with an uncertain etiology and complex yet remain inconclusively debatable regarding its pathophysiological mechanisms of fusion and fission theories. Among all types of CT, parasitic CT, especially the pygopagus sub-type, is exceedingly rarer. To the best of the authors' knowledge, no parasitic CT had been reported in Papua, and this is the first finding in South Papua.

CASE REPORT

Herein, a 30-year-old multigravida female with 37th-week gestation, previous twice spontaneous miscarriage, and non-adequate antenatal care history is presented with a chief complaint of painful construction and greenish fluid leakage from the vagina, with an examination that showed a cephalic presentation with a "peculiar" big mass at the upper uterus and complete cervical dilation toward second-stage inpartu. Vaginal delivery was performed with a complication of obstructed labor due to uncommon dystocia with a suspected "big mass" below the fetal buttocks and intrapartum dead. Intrapartum transabdominal ultrasound demonstrates a gross anatomically like an organ inside a fluid-filled mass with unidentified parts, leading to a suspected type of congenital malformation at the baby's sacral region. Emergency C-section was done with findings of parasitic pygopagus CT, showing an attachment of a large irregular fluid-filled mass-like incomplete twin (parasite) with palpable soft tissue and bony structure inside to the buttocks of a male autosite twin, and an additional third leg which happened to be an under-developed lower extremity with a sacrum-like structure.

CONCLUSIONS

An obstetrician's routine ANC and critical radiological evaluation will increase the odds of identifying CT or other congenital malformations to provide better delivery planning or further management. Increasing maternal health knowledge in society, improving medical skills and knowledge levels for health providers, and advancing supporting facilities and specialists are future strategies for managing and preventing such cases in low-middle-income countries.

Monosymmetros Cephalothoracopagus Tetrabrachius and Tetrapus Piglets with Syndromic Evolution

Conjoined twins are rare congenital malformations that have been reported in mammals. Two different cases are presented in this study. Case No. 1 features monocephalic, thoracopagus-conjoined twin piglets with anencephaly and palatoschisis of the Pietrain breed, and case No. 2 features monocephalic, thoracopagus conjoined twin piglets with palatoschisis and bifid root tongue of a mixed breed. These cases were examined using post-mortem and computed tomography (CT) examinations. In both cases, the conjoined symmetrical twins had a single head, one neck, and fused thoracic cavities, while the abdominal cavities were separated. Similarly, in both cases, they had four forelimbs and four hindlimbs and duplicated foramen magnum. During CT examination, in case No. 1, severe abnormalities were observed in the skull and vertebral column. In the left twin, occult dysraphism was seen from the C2 vertebra until the end of the vertebral column, and in the right twin, from the C3 vertebra until the end of the state vertebral level. In case No. 2, the oral cavity contained a tongue with a bifid root connected with one hyoid bone, and the soft palate presented a small cleft. During CT examination, the parietal bone and the occipital bones were partially duplicated. This case also presented occult dysraphism, but only in the cervical vertebrae, C1-C6 for the left twin and C1-C5 for the right twin. In both cases, abnormalities of the internal organs were revealed during necropsy. Conjoined twins with multiple congenital anomalies presented here enhance our understanding of the various clinical forms of conjoined cases in veterinary medicine.

Monochorionic Twinning in Bioengineered Human Embryo Models

Monochorionic twinning of human embryos increases the risk of complications during pregnancy. The rarity of such twinning events, combined with ethical constraints in human embryo research, makes investigating the mechanisms behind twinning practically infeasible. As a result, there is a significant knowledge gap regarding the origins and early phenotypic presentation of monochorionic twin embryos. In this study, a microthermoformed-based microwell screening platform is used to identify conditions that efficiently induce monochorionic twins in human stem cell-based blastocyst models, termed "twin blastoids". These twin blastoids contain a cystic GATA3+ trophectoderm-like epithelium encasing two distinct inner cell masses (ICMs). Morphological and morphokinetic analyses reveal that twinning occurs during the cavitation phase via splitting of the OCT4+ pluripotent core. Notably, each ICM in twin blastoids contains its own NR2F2+ polar trophectoderm-like region, ready for implantation. This is functionally tested in a microfluidic chip-based implantation assay with epithelial endometrium cells. Under defined flow regimes, twin blastoids show increased adhesion capacity compared to singleton blastoids, suggestive of increased implantation potential. In conclusion, the development of technology enabling large-scale formation of twin blastoids, coupled with high-sensitivity readout capabilities, presents an unprecedented opportunity for systematically exploring monochorionic twin formation and its impact on embryonic development.

Morphological variations on vital systems in a conjoined twin

Conjoined twins (CTs), popularly referred to as Siamese twins, are a rare anomaly due to monochorionic and monoamniotic twin pregnancies. Dicephalus dibrachius dipus, a type of parapagus conjoined twin which is characterized by possessing two arms, two legs, a single trunk and two heads, epidemiologically, is an even rarer occurrence of CTs. In this article, a rare, well-preserved anatomical specimen of a dicephalus dibrachius dipus conjoined twin is presented. This study was conducted in a specimen which is part of the collection of the Embryology Museum of the institution by donation and approved by the Research Ethics Committee (REC). The female conjoined twins were born at full-term by cesarean section in the 1970s and died hours after birth. A thorough anatomical description was made through observational analysis, computed tomography and 3D reconstructed images. Major abnormalities were observed in the cardiovascular, respiratory and digestive systems. The internal anatomy exhibited a heart with three atria, two ventricles, two aortic arches, two pulmonary arteries, one innominate venous trunk and a respiratory system with two tracheas and four lungs. No other report was similar to our three atria heart description. This article provides a thorough anatomical description of all systems, which is valuable information for further studies on CTs.

Monochorionic triplet pregnancy complicated by conjoined twins and early twin-twin transfusion syndrome

BACKGROUND

The condition of monozygotic, monochorionic triplet fetuses with a pair of conjoined twins is extremely rare (close to one in a million births), presents challenges in its management, and with poor prognosis.

CASE REPORT

We report a case of monochorionic diamniotic triplet pregnancy, ultrasound at 14 weeks shows a pair of conjoined thoracopagus fetuses, sharing heart, liver, and umbilical cord, in addition to omphalocele. The third fetus, without malformations, presents signs of early heart failure compatible with twin-to-twin transfusion syndrome. It was decided to carry out expectant management where at 18 weeks, intrauterine death of the three fetuses occurs. An abortion is performed by hysterotomy.

CONCLUSIONS

The treatment in these cases is discussed, three management options have been proposed: expectant management, selective reduction of the conjoined fetuses, or termination of the pregnancy. A review of the literature found only 12 cases with this combination of pathologies, in which only 3 normal fetuses (25%) survived and none of the conjoined twins survived. To our knowledge, this case is the first of a monochorionic triplet pregnancy with conjoined fetuses complicated with early twin-to-twin transfusion.

Phenotypically Discordant Anomalies in Conjoined Twins: Quirks of Nature Governed by Molecular Pathways?

A multitude of additional anomalies can be observed in virtually all types of symmetrical conjoined twins. These concomitant defects can be divided into different dysmorphological patterns. Some of these patterns reveal their etiological origin through their topographical location. The so-called shared anomalies are traceable to embryological adjustments and directly linked to the conjoined-twinning mechanism itself, inherently located within the boundaries of the coalescence area. In contrast, discordant patterns are anomalies present in only one of the twin members, intrinsically distant from the area of union. These dysmorphological entities are much more difficult to place in a developmental perspective, as it is presumed that conjoined twins share identical intra-uterine environments and intra-embryonic molecular and genetic footprints. However, their existence testifies that certain developmental fields and their respective developmental pathways take different routes in members of conjoined twins. This observation remains a poorly understood phenomenon. This article describes 69 cases of external discordant patterns within different types of otherwise symmetrical mono-umbilical conjoined twins and places them in a developmental perspective and a molecular framework. Gaining insights into the phenotypes and underlying (biochemical) mechanisms could potentially pave the way and generate novel etiological visions in the formation of conjoined twins itself.

History and highlights of the teratological collection in the Narrenturm, Vienna (Austria)

The collection of the Narrenturm in Vienna houses and maintains more than 50,000 objects including approximately 1200 teratological specimens; making it one of the biggest collections of specimens from human origin in Europe. The existence of this magnificent collection-representing an important resource for dysmorphology research, mostly awaiting contemporary diagnoses-is not widely known in the scientific community. Here, we show that the Narrenturm harbors a wealth of specimens with (exceptionally) rare congenital anomalies. These museums can be seen as physical repositories of human malformation, covering hundreds of years of dedicated collecting and preserving, thereby creating unique settings that can be used to expand our knowledge of developmental conditions that have to be preserved for future generations of scientists.

The role of the University of Padua medical school in the study of conjoined twins between 18th and early 19th century

The Medical School of Padua (Italy) contributed profoundly to the study of teratology. Many famous physicians and professors of medicine, such as Liceti, Vallisneri, Morgagni, and Malacarne, have studied and investigated these anomalies to better understand the causes and to find a potential explanation, often preserving the specimens for future studies. The present study highlights some historical cases of conjoined twins and a conjoined triplet preserved at the Morgagni Museum of Human Anatomy to show the development of medical theories in the teratological field between the 18th and early 19th century. This approach will provide insights into different study methods and ideas of some of the most famous scholars working in Padua at that time. The current article focuses on rare cases, both human and animal, that were encountered by physicians who worked in the Veneto area in the late 18th and early 19th century. Their detailed descriptions are not only of historical but also of contemporary dysmorphological value.

A Detailed Description and Discussion on Conjoined Twins

Conjoined twins are described as having been physically fused during pregnancy and delivery. They were first mentioned a long time ago when there was not much known about this. They share some organs that are vital for survival, like the heart; these twins are almost impossible to save, but there are some cases wherein there is evidence of their survival. The article aims to present a unique discussion on conjoined twins. This article talks about the formation of conjoint twins, their types and nomenclatures, embryological concepts, past history/traditional tales, case studies, and the medical enhancements happening in this area. Both fission and fusion are thought to contribute to the disease. A monozygotic twin pregnancy cleaves when it occurs more than thirteen days after fertilization. There is just one placenta and one womb for conjoined twins (one amniotic sac). The twins that are born and stay alive after delivery usually stay alive for a few days or weeks. It’s pretty rare for them to live a long prosperous life, but this article shows the otherwise, too, like the Siamese twins, which is a unique example of conjoint twins who lived for a long time. This kind of pregnancy is a complex procedure that needs to be managed by a team of professionals.

A Case of Ischiopagus Dicephalus Conjoined Twins with Tetrabrachius Bipus from Dessie, Ethiopia

The development of conjoined twins always catches the eyes of researchers and clinicians. Beyond the rareness of the cases, how they develop is a debatable issue. This report presented a case of ischiopagus conjoined twins who had two heads (dicephalus), four upper extremities (tetrabrachius), and were joined below the chest with two lower extremities (bipus). The twin’s mother was referred from a primary hospital to Dessie Comprehensive Specialized Hospital for proper management of twin pregnancy, where a cesarean section was performed. The mother and her husband have no family history of birth defects or exposure to known teratogens. On imaging, the twins had separate hearts, lungs, and kidneys but a single liver, spleen, stomach, and intestine. They also shared genitourinary structures: a single penis with sub-coronal hypospadias and one imperforate anus. In addition, their placenta was single with one umbilical vein and two umbilical arteries. The conjoined twins had multiple accompanying cardiovascular anomalies but no external craniofacial, extremity, or brain anomalies. They passed away after 36 hours of follow-up in the neonatal intensive care unit at Dessie Comprehensive Specialized Hospital.

Conjoined Twins in Guinea Pigs: A Case Report

Simple Summary

Cases of newborn connected twins, so-called Siamese twins, are well known in humans, laboratory mammals, domestic and wild birds, reptiles, amphibians and fish. This report describes a unique case of newborn conjoined twins in guinea pigs (Cavia aperea f. porcellus). Connected twins in guinea pigs have been very rare, and there are only a few previous reported cases. This report is only the fourth described case of the birth of conjoined guinea pigs. They were born in breeding in the Czech Republic in 2020. The conjoined twins were males connected in the upper body by a cephalopagus-type connection, which has occurred in all three previous reports. The skeletons of both the bodies were connected by a broad shared skull and sternum. Both of the fused bodies had their own hearts and livers, but the lungs were mutual. The issue of this anomaly has not yet been clearly explained.

Abstract

The report describes a unique case of newborn conjoined twins in guinea pigs (Cavia aperea f. porcellus). Connected twins in guinea pigs have been very rare, and there are only a few previous reported cases. The newborns were stillborn in breeding in the Czech Republic in 2020 as two bodies conjoined into one. The external and internal structure of the body and the type of connection of both of the bodies are described. The weights of selected internal organs of the twins are compared with those of normally developed newborn guinea pigs.

Conjoined twins and conjoined triplets: At the heart of the matter

Conjoined triplets are among the rarest of human malformations, as are asymmetric or parasitic conjoined twins. Based on a very modest corpus of recent literature, we applied the embryonic disk model of conjoined twinning to 10 previously reported cases involving asymmetric anatomical multiplications to determine whether they concerned conjoined twins or conjoined triplets. In spite of their phenotypic similarities, we diagnosed four of these cases as conjoined twins and three of them as conjoined triplets. In the remaining three cases, no definite diagnosis could be made, as essential information was lacking from the reports. We conclude that it is not necessarily the expected duplication or triplication of structures that points to the correct diagnosis in these cases, but the number and mutual position of the hearts they presented with. Considering their rarity we stress to thoroughly investigate and describe internal (dys)morphology in novel cases of (asymmetric) conjoined twins and triplets to further unravel their pathogenicity and come to the correct diagnoses.

Excellent perinatal outcome of monoamniotic twin pregnancy with timely diagnosis and optimal management - a retrospective cohort study

OBJECTIVES

Monoamniotic twins represent a high-risk pregnancy requiring intense follow-up, elective birth and careful consideration of the mode and timing of delivery. We conducted this study to evaluate the perinatal and neonatal outcomes of monoamniotic twin pregnancies in the largest tertiary hospital in Finland.

METHODS

This was a retrospective cohort study including all monoamniotic twin pregnancies during a 17-year period (2002-2018) managed in Helsinki University Hospital. Data on mothers and children were collected from patient files. Chorionicity and amnionicity were defined in first-trimester ultrasound screening.

RESULTS

There were altogether 31 monoamniotic twin pregnancies during the study period, including four cases of conjoined twins which all underwent termination of pregnancy, and three miscarriages. In the remaining 24 pregnancies that continued past 24 weeks of gestation there was 97.9% survival (one intrauterine death). Three pregnancies were complicated with twin-to-twin transfusion syndrome. All children were delivered by cesarean section with a mean gestational age of 32 + 5 weeks (27 + 1-34 + 2 weeks). Respiratory distress syndrome (RDS) was observed in 57% (27/47) of neonates and grade I-II intraventricular haemorrhage (IVH) in 6.3% (3/47) of neonates. There were no neonatal deaths and no maternal complications.

CONCLUSIONS

Monoamniotic twinning is a rare form of pregnancy and carries risks for perinatal and neonatal complications. With timely diagnosis, close monitoring in specialized feto-maternal unit and elective delivery at 32-34 weeks the outcome is usually excellent.

Extended reality visualization of medical museum specimens: Online presentation of conjoined twins curated by Dr. Jacob Henle between 1844-1852

Background

The purpose of this study is to characterize a full-term conjoined twins' cadaver curated by Dr. Jacob Henle sometime between 1844 and 1852 and demonstrate digital distribution of an old and rare medical museum specimen using an extended reality (XR) model workflow.

Methods

The cadaver (Preparation 296) is in the Department of Anatomy and Cell Biology at the University of Heidelberg. An XR display workflow comprises image capture, segmentation, and visualization using CT/MR scans derived from the cadaver. Online radiology presentation to medical students focuses on diagnostic characteristics of anatomical systems depicted with XR models.

Results

Developmental defects in Preparation 296 include duplicated supradiaphragmatic structures and abnormal osteological features. Subdiaphragmatically, the gut is continuous on the right, but terminates at the distal esophagus on the left. One large liver occupies the abdomen with one spleen located on the left side. Observations suggest duplication of the primitive streak and separate notochords rostrally. Duplication occurs near the yolk sac and involves midgut formation while secondary midline fusion of the upper extremities and ribs likely results from the proximity of the embryos during development. Medical students access the model with device agnostic software during the curricular topic "Human Body Plan" that includes embryology concepts covering mechanisms of twinning.

Conclusions

The workflow enables ease-of-access XR visualizations of an old and rare museum specimen. This study also demonstrates digital distribution and utilization of XR models applicable to embryology education.

First Successful Separation of Craniopagus Twins in India—Plastic Surgical Considerations

Separation of total vertical craniopagus with shared venous sinuses poses multiple challenges. Provision of soft-tissue cover to the exposed brains at the time of total separation is one of them, due to the large size of the defect and paucity of local tissues. Staged separation of twins is advised with partial venous and parenchymal disconnection in the first stage and total separation in the second stage. Tissue expanders are inserted in the first stage, and second stage planned to coincide with the period of adequate expansion. In the child being reported, emergency second stage was done due to the deteriorating general condition of the children. Left with inadequate expanded skin, the critical defect in a twin was managed with bilateral trapezius myocutaneous flaps. High ionotropic support of the postoperative period resulted in superficial necrosis of the flap, which was managed by debridement, allograft application and autograft later. Both twins had well-healed wounds by 3 months.

Utility of Fetal Magnetic Resonance Imaging After Ultrasound in Differentiating Dicephalic Dibrachius Dipus Twin Gestation From Craniopagus Parasiticus

Conjoined twins represent a very rare congenital anomaly, and the dicephalic dibrachius dipus (DDD) type of conjoined twinning is so rare that the exact prevalence is unknown. Only a few published case studies have mentioned this anomaly. Not enough data are available where antenatal ultrasonography (USG) and MRI have been employed in the workup of such cases. This study describes the case of a 24-year-old woman who came to our department for an anomaly scan at 25 weeks of gestation and was diagnosed with a dicephalic type of conjoined twinning with multiple anomalies. However, USG could not differentiate between DDD twinning and craniopagus parasiticus; hence, the patient was referred for fetal MRI. On MRI, the diagnosis of DDD was confirmed. In craniopagus parasiticus twinning, the surgical removal of the parasitic head can allow an everyday life. However, DDD twinning with multiple anomalies is not compatible with life, and the mother was thoroughly explained the grave prognosis. In such doubtful cases, fetal MRI should always be employed to ascertain the diagnosis for proper management and counseling.

Conjoined twins in dichorionic diamniotic triplet pregnancy: a report of three cases and literature review

BACKGROUND

Conjoined twins are a rare and serious complication of monochorionic twins. The total incidence is 1.5 per 100,000 births, and about 50% are liveborn. Prenatal screening and diagnosis of conjoined twins is usually performed by ultrasonography. Magnetic resonance imaging can be used to assist in the diagnosis if necessary. Conjoined twins in dichorionic diamniotic triplet pregnancy are extremely rare.

CASE PRESENTATION

We reported three cases of dichorionic diamniotic triplet pregnancy with conjoined twins. Due to the poor prognosis of conjoined twins evaluated by multidisciplinary teams, selective termination of conjoined twins was performed in three cases. In case 1, selective reduction of the conjoined twins was performed at 16 gestational weeks, and a healthy female baby weighing 3270 g was delivered at 37 weeks. In case 2, the conjoined twins were selectively terminated at 17 weeks of gestation, and a healthy female baby weighing 2760 g was delivered at 37 weeks and 4 days. In case 3, the conjoined twins were selectively terminated at 15 weeks and 2 days, and a healthy female baby weighing 2450 g was delivered at 33 weeks and 6 days. The babies of all three cases were followed up and are in good health.

CONCLUSION(S)

Surgical separation is the only treatment for conjoined twins after birth. Early determination of chorionicity and antenatal diagnosis of conjoined twins in triplet gestations are critical for individualized management options and the prognosis of normal triplets. Expecting parents should be extensively counseled by multidisciplinary teams. If there are limitations in successful separation after birth, early selective termination of the conjoined twins by intrathoracic injection of potassium chloride may be a procedure in dichorionic diamniotic triplet pregnancy to improve perinatal outcomes of the normal triplet.

Dutch teratological collections and their artistic portrayals

Several teratologic collections containing specimens with malformations and syndromes are maintained in a number of Dutch anatomical museums. Technically, these are not works of art or antiquities. However, many have been depicted in illustrations of such high quality that they merit discussion here. We review a selection of specimens and their artistic portrayals which find their origin in four Dutch teratological collections. These museum specimens are more than just intriguing objects for the inquisitive museum visitor. As we will substantiate, these specimens—and their artistic depictions—can be used to find and describe rarely occurring birth defects, provide etiopathogenetic information and are a source of novel diagnosis. Additionally, we briefly discuss the ethical aspects and motivations of exhibiting these specimens, as these collections have to be protected meticulously by the new generation of museum professionals, who eventually determine what kind of past our future will have. It is therefore imperative that these collections of antique specimens are treasured as their importance is easily overlooked.

Characterizing the coalescence area of conjoined twins to elucidate congenital disorders in singletons

Shared anomalies, always located close to the area of coalescence and observable in virtually every type of conjoined twinning, are currently seen as separate anomalies caused by mostly unknown and seemingly unrelated pathways rather than being connected to the twinning mechanism itself. Therefore, most (case) reports about conjoined twins are mere descriptions of (external) dysmorphologies lacking reflections on the possible origin of their concomitant anomalies. As we will demonstrate in this article, shared anomalies are influenced, and in some cases solely and sequentially explained, by interaction aplasia and neo‐axial orientation; two embryological mechanisms to which each set of conjoined twins is subjected and are responsible for their ultimate phenotypical fate. In this review, we consider how the ventral, lateral and caudal conjunction types and their intermediates determine the phenotypic presentation of the twins, including patterns of shared malformations and anomalies, which in themselves can be indistinguishable from those encountered in singleton cases. Hence, it can be hypothesized that certain anomalies in singletons originate in a fashion similar to that in conjoined twins.

Conjoined twins in 2020 - state of the art and future directions

PURPOSE OF REVIEW

A number of high profile conjoined twin separations have been extensively covered by the world media. Anaesthesia for conjoined twins is a procedure rarely experienced by paediatric anaesthetists. The increased survival of the twins has prompted discussion as to the most appropriate selection of patients, teams and hospitals to provide exceptional anaesthetic care.

RECENT FINDINGS

The number of conjoined twins presenting for surgery remains low with many infants not surviving foetal or early neonatal life. Anaesthetic management of less common conjoined infants such as craniopagus twins has highlighted the benefit of careful patient selection, extensive preoperative investigations and meticulous multidisciplinary team planning. The role of simulation of possible adverse perioperative events has been highlighted. Three dimensional anatomical models and virtual reality systems have permitted surgical planning in advance of actual intervention. A number of legal and ethical concerns have been reported especially in the setting of emergency separation where surgery is likely to contribute to death of one of the twins.

SUMMARY

There appears to be an expanding role for international teams with extensive separation experience becoming involved in international teleconferencing to improve patient management in low-resource countries. Whether the perioperative outcome is better when the conjoined twins are transferred to major centres for surgery or teams operate in the twin's country of origin remains to be seen.

Symmetric and ventrally conjoined twins: prenatal evaluation by ultrasound and magnetic resonance imaging and postnatal outcomes

OBJECTIVE

To review the perinatal and long-term outcomes of symmetric and ventrally conjoined twins evaluated prenatally by ultrasound and fetal magnetic resonance imaging (MRI).

METHODS

From March 2010 to January 2019, cases of symmetric and ventrally conjoined twins, who were prenatally diagnosed and referred to the Clínica Diagnóstico por Imagem (CDPI), Rio de Janeiro, Brazil, for prenatal evaluation by ultrasound and MRI were selected. The postnatal information was collected from hospitals where the twins were born and/or treated and from parents' verbal and written information.

RESULTS

Four cases of symmetrical and ventrally conjoined twins were selected. Of these, two were omphalopagi and two thoracopagi. One pair of thoracomphalopagus died early in utero and the other died 6 days after birth. The outcome of the two omphalopagus pairs were separation in emergency surgeries after birth, with neonatal demise of one of the twins due to congenital malformations. In cases of omphalopagi, fetal MRI presented important information of the twins' anatomy before emergency separation of both pairs.

CONCLUSION

Despite the apparently similar conditions of twins with ventral fusion, ventrally attached twins have very different outcomes, most adverse for thoracomphalopagus and related to the singular anatomy of the pair, associated malformations and the extension of the adhesion, requiring individual evaluation of the cases. Fetal MRI is as an important tool for the postnatal surgery management of twin neonates, providing crucial information in cases where urgent separation is required.