Magnetic resonance imaging and ultrasonography in the antenatal evaluation of conjoined twins

Three-dimensional ultrasound for prenatal assessment of conjoined twins: additional advantages?

Conjoined twins are a rare, but serious, complication of monozygotic twins. Early prenatal diagnosis of conjoined twins is increasingly made with transvaginal ultrasound and color Doppler studies. Most prenatally diagnosed conjoined twins are terminated due to the high perinatal mortality, but advancement in pediatric surgery has allowed for successful postnatal separation in a small number of cases, and some parents may consider this option over termination of pregnancy. It is important to get a detailed prenatal ultrasound for the site and extent of fusion for an accurate categorization. Three-dimensional ultrasound (3DUS) provides images that can facilitate counselling for the parents. Additional information that impacts on diagnosis, prognostication, and perinatal management of conjoined twins could be obtained from selective use of 3DUS, particularly those with atypical fetal union. Most of the proposed additional benefits of 3DUS are based on case reports. Magnetic resonance imaging (MRI) has been increasingly used for the purpose of identifying intricate organ sharing. Because of the rarity of this condition, and the heterogeneity of fetal fusion, added benefits of either 3DUS or MRI for prenatal diagnosis and perinatal management of conjoined twins have not been demonstrated by well-conducted clinical trials. This article aims to review clinical application of various 3DUS display modes in prenatal assessment of conjoined twins, focusing on their potential additional benefits, risks and misuses. 3DUS may help detecting additional findings that are not possible with 2DUS, but, it has not been scientifically shown to improve the survival rate of the twins or reduce maternal morbidity.

Parasitic twin with gastroschisis is one of the rarest variant of conjoined twins: a case report

We report a case of parasitic twin or incomplete or heteropagus twining of extra portions of a pelvis, lower and upper limbs, duplication of genitalia and herniation of intestinal tract with spleen-variant of conjoined twinning (CT) consistent with fusion of two embryos followed by resorption of the caudal half of one of them, resulting in a normal male baby with the upper half of a male parasitic twin fused to his chest.

Conjoined twins

Conjoined twins have been a source of fascination for both the general public and the medical profession since time immemorial. Their birth was initially viewed as an ominous sign of impending disaster. This was followed by a prolonged period through the Middle Ages and into the nineteenth century when they were regarded as freaks or monstrosities and were exhibited with substantial financial reward at circuses and sideshows. Recently, conjoined twins have attracted intense media interest, which has coincided with increasing success in their separation. This article gives an overview of the role of prenatal ultrasound in assessing the prognosis and discusses the post-natal surgical management and outcome.

Prenatal diagnosis of cephalothoracopagus janiceps disymmetros using three-dimensional power Doppler ultrasound and magnetic resonance imaging

We report the prenatal imaging findings of a rare case of cephalothoracopagus janiceps disymmetros diagnosed at 28 weeks' gestation. Two-dimensional ultrasound and magnetic resonance imaging demonstrated janiceps conjoined female twins with a single fused cranial vault, duplicated cerebra, two faces, four eyeballs, a fused thorax, two hearts, two thoracic spines, eight limbs and polyhydramnios. Three-dimensional and power Doppler ultrasound established the definitive classification of cephalothoracopagus conjoined twins and displayed the shared circulation between the two separate hearts.

Gemelidade imperfeita: avaliação pelos métodos de imagem

Os gêmeos acoplados são raros e constituem um desafio para os radiologistas e cirurgiões pediátricos. O estudo pré-natal é essencial para a definição da fusão anatômica e de outras anormalidades associadas, visando o adequado planejamento cirúrgico e a avaliação do prognóstico fetal. Os autores apresentam os achados clínicos e de imagem de um caso de gêmeos toracópagos, unidos pela porção anterior do tórax e compartilhando o coração e o fígado, diagnosticados ao estudo ultra-sonográfico e submetidos ao estudo por ressonância magnética fetal intra-útero para confirmação dos achados e detecção de outras anormalidades.

Role of magnetic resonance imaging in fetal surgery

Prenatal magnetic resonance imaging (MRI) has several advantages over obstetric ultrasound, including a larger field of view, superior soft-tissue contrast, more precise volumetric measurements, and greater accuracy in the demonstration of intracranial abnormalities. Prenatal MRI has been shown to positively and incrementally influence management in a substantial proportion of patients being considered for fetal intervention. Despite these findings, precise indications for prenatal MRI in the setting of fetal surgery are not yet established, because both prenatal MRI and fetal surgery are relatively new techniques that remain in evolution. Conditions in which prenatal MRI appears to contribute to fetal surgical planning and postoperative evaluation are described in this review. These conditions include congenital diaphragmatic hernia, cystic adenomatoid malformation, sacrococcygeal teratoma, complicated twin pregnancies, upper airway obstruction, and myelomeningocele.

Cardiac catheterization in diagnosis and management of congenital heart disease in thoracopagus conjoined twins

Over the last two decades, surgical separation of thoracopagus conjoined twins has become increasingly feasible. Delineation of the degree of cardiac involvement is essential to establish the feasibility of surgical separation. We describe our experience of cardiac catheterization both in the diagnosis and management of nine sets of thoracopagus twins who presented to a single center over three decades and discuss its role in conjunction with other modern diagnostic modalities.

Intrauterine effects of electromagnetic fields--(low frequency, mid-frequency RF, and microwave): review of epidemiologic studies

Electromagnetic radiations are named according to frequency or to wavelength (which is inversely proportional to frequency) and create electromagnetic fields (EMFs). Frequencies widely vary according to sources: high-voltage power lines, electrically heated beds, MRI, VDTs, microwave ovens, satellite, and radio/TV transmissions or cellular phone transmitters/receivers. Public concern has increased about the potential health effects of EMFs. There are arguments in favour of EMFs being biologically active, but no mechanism has been identified that explains the link between EMFs and bioeffects. Human data reviewed concern the potential reproductive effects (mainly spontaneous abortions, low birthweight and congenital malformations) of exposure to sources of EMFs: maternal residence, electrically heated beds, occupational exposure (mainly video display terminals), and medical exposures. The available epidemiologic studies all have limitations that prevent to draw clearcut conclusions on the effects of EMFs on human reproduction. EMFs are ubiquitous and unavoidable exposures. The matter of possible effects cannot be considered closed, but until our understanding of the biologic important parameters of EMFs exposures is stronger,design of new studies will be difficult and small epidemiologic studies are unlikely to provide definitive answers and should not be given high priority. No conclusion can be drawn for radiofrequencies and microwaves because of lack of data. There is no convincing evidence today that EMFs of the sort pregnant women or potential fathers meet in occupational or daily life exposures does any harm to the human reproductive process.

Extremely rare type of conjoined twins: cephalothoracopagus deradelphus

Occurrence of conjoined twins (CT) with a chromosomal abnormality is a very rare event. The case presented is that of a cephalothoracopagus Deradelphus twin with one cerebrum and two brain stems joined at the cranial end of the midbrain. This rare condition and its diagnosis and management are discussed with regard to counselling and obstetrical care.

Conjoined twins--the Cape Town experience

This paper records our experience in the management of 25 sets of conjoined twins seen over a 32 year period (1964 - 1996). The twins were classified into 14 complete and symmetrical sets and 11 incomplete or heteropagus. The 14 symmetrical sets included 9 thoracopagus, 2 ischiopagus, 1 craniopagus and 1 omphalopagus twins. In the incomplete heteropagus group there was 1 ischiopagus, one twin being anencepahlic, 2 dipygus, 5 parasitic, 2 fetus-in-fetu and I cranial and caudal. The management is detailed case by case. Overall 10 of 14 symmetrical sets underwent attempts at separation with 16 surviving the procedure, but there were 3 late deaths. In the incomplete group 10 of 11 were operated on with 9 survivors. The importance of a multi-disciplinary approach, the extensive investigations required pre-operatively to define areas of organ and bony conjunction, congenital anomalies of each twin and surgical teamwork is emphasized. Specific problems encountered were identified. In thoracopagus twins the hearts were of paramount importance as conjuction was usually fatal, being associated with major congenital defects. The greater the extent of thoracic cage fusion the greater the chance of associated severe anomaly. Skin expansion to assist coverage of the defects after separation was of great assistance, as was the use of collagen coated vicryl. Evaluation of the liver and pancreatico-biliary systems with isotope excretion scanning was crucial to pre-operative planning. Where there was fusion of the duodenum a single pancreatico-biliary system could be expected and prior strategies for separation and Roux-en-Y enteric drainage of both pancreatic and biliary secretion should be planned. Gastro-oesophageal reflux led to considerable morbidity in both twins of a thoraco-omphalopagus set. In ischiopagus and dipygus conjoined twins bilateral posterior iliac osteotomies were an essential component to anatomic reconstruction of the pelvic ring and wound closure. Also in this group, due to the frequency and extent of shared genital, urinary and ano-rectal structures, long-term morbidity was expected and a component of this might be due to spinal cord tethering, or as in one of our cases, a progressive hydrosyringomyelia. Timing of separation was ideally set at between 5 and 9 months with 6 to 8 weeks of prior tissue expansion but earlier operation was frequently required because of cardio-respiratory problems or organ failure in one twin. In most cases the goal of obtaining separate, independent and intact individuals was achieved.

Teratogen update: electromagnetic fields

Public concern is increasing about the potential health effects of extremely low frequency (ELF) electromagnetic fields (EMFs) naturally present or generated by electrical appliances and those of very low frequency (VLF) fields, like those generated by video display terminals (VDTs). There are arguments in favour of EMFs being biologically active but no mechanism has been identified that explains the link between EMFs and bioeffects. More than 50 studies on exposures of animals to EMFs have been performed within the last few years. Although there were a few statistically significant effects in the studies reviewed, no replicable results were found among laboratories. The extent of effects observed, if any, was always low, and deserves further investigation before relevance to humans can be considered. Human data reviewed concern the potential reproductive effects (mainly) spontaneous abortions, low birthweight, and congenital malformations) of exposure to various sources of EMFs: maternal residence, heated waterbeds, electric blankets, and ceiling heating coils, occupational exposure (mainly video display terminals), and magnetic resonance imaging. The totality of the evidence that is thus far available provides no convincing evidence to indicate that low frequency EMFs of the sort that might be met in occupational or daily life exposures does any harm to the human reproductive process. It is suggested that those counseling pregnant women follow the guidelines established by WHO in agreement with the International Non-ionizing Radiation Committee. This group does not consider that the results of published studies provide a basis for restricting human exposure to electromagnetic fields and radiation.

The antenatal diagnosis of cephalothoracopagus Janiceps conjoined twins

A case of cephalothoracopagus conjoined twins (Janiceps twins) is presented. The abnormality was detected antenatally by the use of ultrasonography and confirmed postnatally, clinically and by computed tomography (CT scan).

Prenatal diagnosis of anatomical connections in conjoined twins by use of contrast magnetic resonance imaging

Omphalopagus conjoined twins were diagnosed by ultrasonography in a pregnant woman at 21 weeks' gestation. In order to clarify the anatomical connections, magnetic resonance imaging (MRI) was performed, having achieved fetal paralysis by intravascular injection of 100 mg of pancuronium into each twin. Prior to MRI, 2 ml of a 0.0001 mmol/ml solution of gadolinium DTPA was also injected into the stomach of one twin. The contrast agent opacified the bowel loops of both twins, indicating bowel to bowel anastomosis. Following pregnancy termination, autopsy confirmed the prenatal diagnosis.

Anatomical study of five prenataly diagnosed sternopagus twins

Among conjoined twins (1 out 50000 births), thoracopagus occurs most frequently and is generally lethal. Our anatomical study of five sets of sternopagus twins (3 female, 2 male) was performed to determine the ability of prenatal sonography to detect these anomalies. Autopsy in four cases revealed identical malformations: common sternum, single malformed heart, joined hepatic parenchyma, and a common small bowel leading to a cystic dilatation situated on the ileal segment at the end of the superior mesenteric artery. The diagnosis of conjoined twins was made in all cases by prenatal sonography at the mean time of 24.6 gestation weeks (range 19-34). The malformations detected by prenatal sonography were a single cardiac mass (all cases), joined hepatic parenchymas (3 cases), and an ileal cystic dilatation (1 case). Pregnancy was terminated in four cases. In one case cesarean delivery was performed, and the infants died 48 hours later. Prenatal sonography currently seems to be the best examination for diagnosis of sternopagus twins and the detection of lethal malformations thus allowing interruption of pregnancy.

Conjoined twins: medical, surgical and ethical challenges

Four sets of conjoined twins were reviewed. One set was of the omphalopagus type with no associated abnormalities and were successfully separated at 12 days of age. The other three were of the thoracoomphalopagus type with major cardiac and other abnormalities, they were not amenable to surgery and did not survive. Conjoined twins require precise clinical and radiological evaluation. Many factors contribute to the management of such twins and ethical issues must be considered before surgical separation is undertaken.

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.

Ischiopagus tetrapus twins: urological aspects of separation and 10-year followup

Conjoined twins occur once in 50,000 births. Only 6% of conjoined twins are of the ischiopagus type in which the twins are joined symmetrically at the pelvis and fusion begins at the level of the common umbilicus. The longitudinal axis extends in a straight line in opposite directions and the genitourinary and gastrointestinal tracts are shared. Tetrapus is a subtype in which all 4 lower extremities are present and oriented at right angles to the axis of the common trunk. Two sets of female ischiopagus tetrapus twins were born in 1977 and successfully separated at the St. Louis Children's Hospital in the following year. We describe the genitourinary and associated anomalies, surgical separation and long-term urological followup of these 2 sets of ischiopagus tetrapus twins.

Effects of pulsing electromagnetic fields on the prenatal and postnatal development in mice and rats: in vivo and in vitro studies

Electromagnetic fields (EMF) might have various biological effects on the developing embryo. We studied the effects of pulsing electromagnetic fields (PEMF) on the in vitro development of preimplantation mouse embryos and of early somite rat embryos as well as on the in vivo development of rat embryos. We used PEMF at frequencies of 1, 20, 50, 70, and 100 Hz with a tension of 0.6 V/m. The embryos were exposed to PEMF throughout the experimental period. PEMF at frequencies of 20 and 50 Hz were embryotoxic, inhibiting over 50% of blastocysts from hatching and further development, all within 72 h of culture. PEMF at frequencies of 50 and 70 Hz induced 22% and 30% incidence of malformations in 10.5 day old rat embryos after 48 h in culture. The main malformations were absence of telencephalic, optic, and otic vesicles and of forelimb buds. In addition, retarded growth and development manifested by fewer somites, reduction in crown-rump length, and retarded closure of the neural tube were found in many embryos. No significant pathological changes were found by TEM in PEMF-exposed embryos. Disappearance of microvilli and collapse of apical parts of endodermal cells were observed by SEM in many yolk sacs of embryos exposed to 50 and 70 Hz PEMF. A slightly reduced litter average, a reduction or increase of weight, and a delay in eye opening was observed among offspring of pregnant rats exposed throughout pregnancy to PEMF at frequencies of 20, 50, and 100 Hz. No malformations were observed among these offspring. The mechanism of PEMF-induced embryotoxicity and teratogeneity is unknown, as is the mechanism of the "protective effects" of the mother on the rat embryos exposed to PEMF in vivo.

Management of conjoined twins

A case of thoracopagus conjoined twins encountered in the second stage of labor is presented. Delivery was possible by the vaginal route after reducing the fetal bulk by destructive operations. Problems in obstetric management of these cases are discussed and the importance of proper antenatal evaluation is stressed.

Twenty-three-year follow-up of separated ischiopagus tetrapus conjoined twins

This paper presents a 23-year follow-up of the separation of ischiopagus tetrapus conjoined twins reported in Annals of Surgery in December 1966. One twin died of septicemia at age 2 years after bilateral pelvic osteotomies for the treatment of her marked pelvic diastasis. The surviving twin has done reasonably well, and her most significant problem is related to her musculoskeletal system. She has an increasing T7-10, L-1 apex right congenital scoliosis with wedged vertebra at T-10, as well as marked pubic diastasis and bilateral subluxation of her hips. This has resulted in a somewhat aberrant physical appearance and a "waddling" gait. Her colostomy functions well and she has normal renal and bladder function. This patient's history illustrates that many problems remain after successful separation of conjoined twins. However these problems are manageable and do not preclude the possibility that such a patient may be a productive member of society.

Use of magnetic resonance imaging in planning the separation of omphalopagus conjoined twins

Magnetic resonance imaging (MRI) was used for the first time in the preoperative planning for separation of conjoined twins. In these omphalopagus infants, MRI showed normal biliary and cardiovascular structures and demonstrated, in detail, a relatively avascular plane through the liver bridge, which enabled safe separation with minimal blood loss at 3 1/2 months of age. A single MRI study supplied information superior to that obtained with multiple previously available imaging studies. MRI should be an essential part of the preoperative workup of all types of conjoined twins.

Intrauterine diagnosis of hydranencephaly by magnetic resonance

Magnetic resonance imaging (MRI) was used to confirm an ultrasound diagnosis of hydranencephaly in utero. MRI provided an accurate anatomical assessment, influencing the pregnancy management. The result supports previous reports suggesting that MRI may be a useful complement to ultrasonography in intrauterine diagnoses.

Surgical problems in the fetus: a multidisciplinary approach

Over a 2 year period, 90 cases of potential fetal pathologic conditions were presented to a multidisciplinary fetal board. Members, including persons from perinatology, neonatology, genetics, radiology, pathology, pediatric surgery, neurosurgery, and urology, met monthly to discuss new referrals, follow-up ongoing cases, and present findings and treatment in delivered cases. Of 90 referred cases, 76 surgical diagnoses occurred in 71 fetuses (79 percent), with central nervous system and genitourinary anomalies predominating. A formal presentation during a single meeting with the variety of specialists necessary to manage surgical problems in the fetus facilitated perinatal management and allowed for the appropriate specialist to counsel the parents as early as possible.