Double Trouble: Complications in Twin Pregnancies.

With the increasing rate of twin pregnancies due to increase in maternal age and use of assisted reproduction, it is important to be aware of unique diseases which occur specifically to twin pregnancies, especially in monochorionic twin pregnancies. These entities include twin to twin transfusion syndrome, twin anemia polycythemia sequence, twin reversed arterial perfusion, cotwin demise, and conjoined twins. Early evaluation and documentation are imperative to guide management which ultimately leads to better patient outcomes.

Three-dimensional ultrasonographic features of diamniotic conjoined twins with body stalk anomaly.

BACKGROUND: Since conjoined twins were thought to be monoamniotic in the past, diamniotic conjoined twins would be improbable theoretically. Body stalk anomaly is a severe defect of the body wall, which is rare among twins. Body stalk anomaly in monochorionic diamniotic conjoined twins has never been reported prenatally so far as we know. CASE PRESENTATION: Here we present an extremely rare case of concordant body stalk anomaly in monochorionic diamniotic conjoined twins. Ultrasonography at 9 + 5 weeks revealed one chorionic and two amniotic cavities, close apposition of abdomen, limited movement, and common umbilical vessels. Follow-up ultrasonography at 11 + 6 weeks and 13 + 2 weeks showed close apposition of the lower abdominal region with cystic structures and a small bowel-like mass between the two fetuses. Three-dimensional ultrasonography assisted in observing the entire appearance of both twins in earlier first trimester, including amnioticity, conjoined region and umbilical vessels. We attribute this diamniotic conjoined twin in our case to the fusion theory. A single yolk sac was observed, challenging the idea that yolk sac number predicts amnionicity. Identification of single yolk sac and its allantois may form a common body stalk during this fusion, leading to concordant body stalk anomaly in monochorionic diamniotic twins. CONCLUSIONS: Our case may provide important insights into both ultrasonographic features and embryogenesis of this extremely rare anomaly.

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

In this article, we provide a comprehensive overview of multiple facets in the puzzling genesis of symmetrical conjoined twins. The etiopathogenesis of conjoined twins remains matter for ongoing debate and is currently cited-in virtually every paper on conjoined twins-as partial fission or secondary fusion. Both theories could potentially be extrapolated from embryological adjustments exclusively seen in conjoined twins. Adoption of these, seemingly factual, theoretical proposals has (unconsciously) resulted in crystallized patterns of verbal and graphic representations concerning the enigmatic genesis of conjoined twins. Critical evaluation on their plausibility and solidity remains however largely absent. As it appears, both the fission and fusion theories cannot be applied to the full range of conjunction possibilities and thus remain matter for persistent inconclusiveness. We propose that initial duplication of axially located morphogenetic potent primordia could be the initiating factor in the genesis of ventrally, laterally, and caudally conjoined twins. The mutual position of two primordia results in neo-axial orientation and/or interaction aplasia. Both these embryological adjustments result in conjunction patterns that may seemingly appear as being caused by fission or fusion. However, as we will substantiate, neither fission nor fusion are the cause of most conjoined twinning types; rather what is interpreted as fission or fusion is actually the result of the twinning process itself. Furthermore, we will discuss the currently held views on the origin of conjoined twins and its commonly assumed etiological correlation with monozygotic twinning. Finally, considerations are presented which indicate that the dorsal conjunction group is etiologically and pathogenetically different from other symmetric conjoined twins. This leads us to propose that dorsally united twins could actually be caused by secondary fusion of two initially separate monozygotic twins. An additional reason for the ongoing etiopathogenetic debate on the genesis of conjoined twins is because different types of conjoined twins are classically placed in one overarching receptacle, which has hindered the quest for answers. Clin. Anat. 32:722-741, 2019. © 2019 Wiley Periodicals, Inc.

Prenatal and postnatal radiologic evaluation of conjoined twins.

Imaging of conjoined twins requires the use of multiple modalities, in both the prenatal and postnatal setting. Prenatal imaging, including both ultrasound and magnetic resonance imaging, benefits from an organized, worksheet-based approach, careful labelling of all images, and adoption of supplemental techniques. Postnatal imaging should be informed by the prenatal imaging findings and should be thoughtfully planned prior to performance. Complete evaluation prior to planned surgical separation will require the use of complementary modalities and multidisciplinary review and discussion.

Role of simulation in preparation for the care of conjoined twins-prenatal preparation to separation.

The rarity and complexity of conjoined twins creates a challenge for prenatal planning, delivery resuscitation, and postnatal management. The modality of simulation offers a safe practice environment for a multidisciplinary group consisting of neonatal providers, nurses, respiratory therapists, and surgeons in which to identify and address clinical decision making, procedural, and behavioral plans related to routine and emergency care of these patients. Simulation-based clinical rehearsals (SbCR) provide a unique opportunity to prepare for rare, complex, and patient specific clinical procedures and scenarios. This primer serves as a revisable tool that promotes the development of proper timing, technique, and confidence to allow for an optimal setting for delivery of safe care to conjoined twins. We describe the development and implementation of a simulation approach to all stages of care from the antenatal life, NICU care, to preparation for postnatal separation of conjoined twins.

Conjoined twins: From conception to separation, a review.

Conjoined twins are suggested to result from aberrant embryogenesis. The two main theories proposed to explain the phenomena are fission and fusion. The incidence rate is 1 in 50,000 births; however, since about 60% of the cases are stillborn, the true incidence is approximated at 1 in 200,000. There is a higher predisposition towards female than male gender with a ratio of 3:1. Conjoined twins are classified based upon the site of attachment. The extent of organ sharing, especially the heart, determines the possibility and prognosis of a separation procedure. Meticulous preoperative evaluation, planning, and preparedness of the team are crucial for a successful separation. Separation of conjoined twins poses several technical, legal, and ethical issues. Clin. Anat. 30:385-396, 2017. © 2017 Wiley Periodicals, Inc.

Leftward Flow Determines Laterality in Conjoined Twins.

Conjoined twins fused at the thorax display an enigmatic left-right defect: although left twins are normal, laterality is disturbed in one-half of right twins [1-3]. Molecularly, this randomization corresponds to a lack of asymmetric Nodal cascade induction in right twins [4]. We studied leftward flow [5, 6] at the left-right organizer (LRO) [7, 8] in thoracopagus twins in Xenopus, which displayed a duplicated, fused, and ciliated LRO. Cilia were motile and produced a leftward flow from the right LRO margin of the right to the left margin of the left twin. Motility was required for correct laterality in left twins, as knockdown of dynein motor dnah9 prevented Nodal cascade induction. Nodal was rescued by parallel knockdown of the inhibitor dand5 [9, 10] on the left side of the left twin. Lack of Nodal induction in the right twin, despite the presence of flow, was due to insufficient suppression of dand5. Knockdown of dand5 at the center of the fused LRO resulted in asymmetric Nodal cascade induction in the right twin as well. Manipulation of leftward flow and dand5 in a targeted and sided manner induced the Nodal cascade in a predictable manner, in the left twin, the right one, both, or neither. Laterality in conjoined twins thus was determined by cilia-driven leftward fluid flow like in single embryos, which solves a century-old riddle, as the phenomenon was already studied by some of the founders of experimental embryology, including Dareste [11], Fol and Warynsky [12], and Spemann and Falkenberg [13] (reviewed in [14]).

Xenopus, an ideal model organism to study laterality in conjoined twins.

Conjoined twins occur at low frequency in all vertebrates including humans. Many twins fused at the chest or abdomen display a very peculiar laterality defect: while the left twin is normal with respect to asymmetric organ morphogenesis and placement (situs solitus), the organ situs is randomized in right twins. Although this phenomenon has fascinated already some of the founders of experimental embryology in the 19th and early 20th century, such as Dareste, Fol, Warynsky and Spemann, its embryological basis has remained enigmatic. Here we summarize historical experiments and interpretations as well as current models, argue that the frog Xenopus is the only vertebrate model organism to tackle the issue, and outline suitable experiments to address the question of twin laterality in the context of cilia-based symmetry breakage.

Dicephalous v. diprosopus sharks: record of a two-headed embryo of Galeus atlanticus and review of the literature.

As far as is known, this paper gives the first description of a two-headed shark embryo belonging to an oviparous species, Galeus atlanticus (Carcharhiniformes: Scyliorhinidae). The specimen was detected among 797 embryos intended for cardiovascular studies, which represents a defect incidence of 0·13%. Each head had a mouth, two eyes, a brain, a notochord and five gill openings on each side. The two heads fused behind the gills. On the single body, there were four anticipated dorsal fins, two anterior, right and left and two posterior, right and left. Ventrally, the specimen possessed two pairs of pectoral fins, a pair of pelvic fins and one anal fin. Two adjacent notochords, two neural tubes and two dorsal aortas ran along the body, which bent 180° at its posterior portion. There were two hearts, two oesophaguses, two stomachs, two livers, but a single intestine with a spiral valve. Previous reports of conjoined twins in sharks are scarce and only refer to oviparous and ovoviviparous species. Seven dicephalous sharks reported so far were similar to the specimen described here, namely, with two totally separated heads on one body. Instead, only one case of diprosopus shark has been reported; it had a single body and a single head with partial duplication of the face. Two further cases described in the literature as dicephalous or simply as abnormal sharks should be better regarded as diprosopus, while another three cases, also considered dicephalous, showed a mixture of characteristics of diprosopia and dicephalia.

Separation of Thoraco-Omphalo-Ischiopagus Conjoined Twins: Surgical Planning, Management, and Outcomes.

BACKGROUND: Conjoined twins are a rare medical phenomenon that offers a unique challenge for medical professionals. The complex anatomy of conjoined twins dictates their survival and amenability to separation, making each case different in terms of medical management, surgical planning, and patient outcomes. Thoraco-omphalo-ischiopagus twins, joined from the thorax to the pelvis, are one of the rarest orientations recorded in the medical literature, and successful separation of this subset of conjoined twins has not been documented. This report presents a novel case of thoraco-omphalo-ischiopagus tetrapus twins who were successfully separated at 10 months of age. The preoperative planning, operative details, and postoperative course are discussed as they relate to the reconstructive effort. METHODS: Three-dimensional medical modeling was pursued early in the planning process and was used to estimate the soft-tissue requirements for reconstruction and to design custom tissue expanders. RESULTS: The reconstructive effort required postponement until respiratory status was optimized. Even with elaborate preoperative planning, primary closure of the abdomen was limited because of tissue edema and other less predictable patient factors. Delayed closure of the abdominal wall was made possible with negative-pressure wound therapy and secondary flap advancements. CONCLUSION: Preoperative coordination with necessary vendors, a multidisciplinary surgical effort, and optimal timing of the surgical intervention all contribute to the successful separation and long-term survival of thoraco-omphalo-ischiopagus conjoined twins. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, V.

Salmonid fish: model organisms to study cardiovascular morphogenesis in conjoined twins?

BACKGROUND: There is a gap in knowledge regarding the cardiovascular system in fish conjoined twins, and regarding the cardiovascular morphogenesis of conjoined twins in general. We examined the cardiovascular system in a pair of fully developed ventrally conjoined salmonid twins (45.5 g body weight), and the arrangement of the blood vessels during early development in ventrally conjoined yolk sac larvae salmonid twins (<0.5 g body weight). RESULTS: In the fully developed twins, one twin was normal, while the other was small and severely malformed. The mouth of the small twin was blocked, inhibiting respiration and feeding. Both twins had hearts, but these were connected through a common circulatory system. They were joined by the following blood vessels: (i) arteria iliaca running from arteria caudalis of the large twin to the kidney of the small twin; (ii) arteria subclavia running from aorta dorsalis of the large twin to aorta dorsalis of the small twin; (iii) vena hepatica running from the liver of the small twin into the sinus venosus of the large twin. Among the yolk sac larvae twins investigated, distinct vascular connections were found in some individuals through a joined v. vitellina hepatica. CONCLUSIONS: Ventrally conjoined fish twins can develop cardiovascular connections during early development, enabling a normal superior twin to supply a malfunctioning twin with oxygen and nutrients. Since the yolk sac in salmonids is transparent, twinning in salmonids may be a useful model in which to study cardiovascular morphogenesis in conjoined twins.

Conjoined Fetal Twins in a Harbor Seal (Phoca vitulina).

In July 2013, a stranded harbor seal (Phoca vitulina) died giving birth to conjoined fetuses. The twins were joined at the abdomen and thoracolumbar spine with the vertebral axis at 180°. The cause of this unique anomaly--a first for this species--was not identified.

Conjoined twins: scientific cinema and Pavlovian physiology.

Through the lens of a 1957 documentary film, "Neural and humoral factors in the regulation of bodily functions (research on conjoined twins)," produced by the USSR Academy of Medical Sciences, this essay traces the entwined histories of Soviet physiology, studies of conjoined twins and scientific cinema. It examines the role of Ivan Pavlov and his students, including Leonid Voskresenkii, Dmitrii Fursikov and Petr Anokhin, in the development of "scientific film" as a particular cinematographic genre in Soviet Russia and explores numerous puzzles hidden behind the film's striking visuals.

The management of conjoined twins: Cardiology assessment.

Structural cardiac defects occur in at least 1 twin in about 75% of conjoined twins with thoracic level fusion. Outcomes after surgical separation of thoracic level conjoined twins have been favorable when the hearts have been separate. However, even in this situation, the outlook is poor for an individual twin with an important cardiac defect. Arterial anastomosis between twin circulations is an important additional consideration, with poor outcomes for perfusion recipient twins. Surgical separation is contraindicated when ventricular level cardiac fusion exists. Cardiac assessment is a key component of prenatal counseling.

La imagenologia médica en el laboratorio de morfología: iconografía / Medical imaging laboratory Morphology: iconography of bicéfalo fetus / A imagiologia médica no laboratório de morfologia: iconografia do feto bicéfalo

El nacimiento de gemelos siameses es un fenómeno extraño en las salas de parto de todo el mundo, son producto de un mismo óvulo que por alguna extraña razón no llegó a dividirse; se presenta 1/50.000 o 1/120.000 nacimientos; se estima que el 50% nace muerto y el 35% muere el primer día de vida; y el 70% son de génerofemenino. Un feto bicéfalo es un producto desarrollado con dos cabezas que se unen entre sí por medio de sus porciones temporo-parietales mediales, estando conectados vascularmente y compartiendo o no órganos entre sí; son de tipo monocigóticos y producidos por la separación anormal o incompleta de la porción axial del disco germinativo bilaminar en etapas avanzadas del desarrollo embrionario. En el presente trabajo se expone un caso de siameses bicéfalo de sexo femenino, cuyo espécimen hacía parte de las colecciones de embriología del Laboratorio de Morfología de la Universidad Tecnológica de Pereira, el cual por registro de Historia Clínica y Consentimiento Informado de la madre, quien lo entregó a la Universidad, fue sometido a descripción anatomopatológica con el fin de exponer aspectos relacionados con las posibles causas que los originaron, así como el diagnóstico prenatal de estos defectos congénitos y su diagnóstico Imagineológico postmortem.

The birth of conjoined twins is a strange phenomenon in the delivery rooms around the world, are the product of a single egg that for some reason did not divide; is presenta1 / 50,000 or 1 / 120,000 births; is estimated that 50% stillborn and 35% die on the first day of life; and 70% are female. A two-headed fetus is a product developed with two heads that are joined together through their temporoparietal medial portions being connected vascularized organs and sharing with each other or not; are monozygotic type and produced by abnormal or incomplete separation of the axial portion of the bilaminar germ disc in advanced stages of embryonic development. In this paper a case of two-headed Siamese female, whose specimen was part of the collections of Morphology Embryology Laboratory of the Technological University of Pereira, who for record medical history and informed consent of the mother who is exposed delivered to the University underwent pathological description to explain aspects of the possible causes of these accidents and the prenatal diagnosis of these congenital defects and postmortem imaging diagnosis.

O nascimento de gêmeos siameses é um fenômeno estranho nas salas de parto de todo o mundo. São produto de um mesmo óvulo, que por alguma estranha razão não chegou a dividir-se; se apresenta em 1/50.000 ou 1/120.000 nascimentos. Estima-se que 50% nascem mortos e 35% morre ao primeiro dia de vida; e 70% são do gênero feminino.Um feto bicéfalo é um produto desenvolvido com duas cabeças que se unem entre si por meio de suas porções temporão-parietais mediais, estando conectados vascular-mente e compartilham ou não órgãos entre si; são de tipo monozigóticos e produzi-dos pela separação anormal ou incompleta da porção axial do disco germinativo bi laminar em etapas avançadas do desenvolvimento embrionário. Neste trabalho se expõe o caso de siamesas bicéfalas do sexo feminino, cujo espéci-men fazem parte das coleções de embriologia do Laboratório de Morfologia da Uni-versidade Tecnológica de Pereira, que por registro de Historia Clínica e Consenti-mento Informado da mãe, que o entregou à Universidade, foi submetido a descrição anatomopatológica com o fim de expor aspectos relacionados às possíveis causas que os originaram, assim como o diagnóstico pré-natal destes defeitos congênitos e seu diagnóstico Imagiológico post-mortem.

Going out on a limb for a difficult diagnosis: a case report.

Sacral tumors with fetiform features are rare and pose a diagnostic challenge to the ultrasonologist. Sacrococcygeal teratomas (SCT) and parasitic twins can have very similar sonographic features but have different implications to an affected pregnancy. While postnatal histopathology is ultimately necessary to distinguish between a SCT and a heteropagus twin, certain characteristics, such as the presence of a vertebral column and the pattern and rate of tumor growth, may be useful to guide counseling and management decisions.