Síndrome de transfusão feto-fetal: revisão de literatura / Twin-twin transfusion syndrome: a literature review

A síndrome de transfusão feto-fetal é uma complicação das gestações gemelares monocoriônicas. Além de ocorrer comumente no segundo trimestre, apresenta elevada morbimortalidade fetal e neonatal, e taxas de incidência que variam de 10 a 15% dentre todas as gravidezes monocoriônicas. O objetivo deste estudo é realizar uma revisão de literatura a partir de levantamento bibliográfico acerca dos principais aspectos epidemiológicos, clínicos e terapêuticos da STFF. A base de dados PubMed foi consultada, uma vez que os termos de pesquisa utilizados foram "síndrome de transfusão feto-fetal", "diagnóstico" e "tratamento". Obtiveram-se sessenta e oito artigos de revisão de literatura e/ou revisão sistemática, sendo que apenas vinte e nove foram selecionados após aplicação dos critérios de elegibilidade. Em relação à fisiopatologia, a síndrome é explicada pela transferência sanguínea direta entre os fetos gemelares através de anastomoses arteriovenosas placentárias, conceitualmente determinando a existência de um feto receptor e outro doador. Embora as gestantes comumente se apresentam assintomáticas, as repercussões clínicas fetais costumam ser graves. O diagnóstico é exclusivamente ultrassonográfico e deve ser feito o mais precocemente possível, ressaltando-se a importância da detecção da corionicidade da gestação gemelar, além de acompanhamento ultrassonográfico seriado para rastreio do desenvolvimento da síndrome. Apesar de ainda não haver protocolo de tratamento bem estabelecido, a ablação dos vasos placentários a laser é tida como o padrão-ouro dentre as opções terapêuticas disponíveis. Apresenta elevada taxa de sobrevida de pelo menos um dos fetos e baixos índices de sequelas neurológicas neonatais, podendo ser realizada somente até a 26ª semana de gestação.

Twin-twin transfusion syndrome is a complication of monochorionic twin pregnancies. In addition to commonly occurring in the second trimester, it has high fetal and neonatal morbidity and mortality and incidence rates ranging from 10 to 15% among all monochorionic pregnancies. This study aims to perform a literature review based on a bibliographic survey about the main epidemiological, clinical and therapeutic aspects of TTTS. The PubMed database was consulted, as the search terms used were "twin-twin transfusion syndrome", "diagnosis", and "treatment". Sixty-eight literature review and systematic review articles were obtained, and only twenty-nine were selected after applying the eligibility criteria. About the pathophysiology, the syndrome is explained by direct blood transfer between the twin fetuses through placental arteriovenous anastomoses, determining the existence of a recipient fetus and another donor. Although pregnant women are usually asymptomatic, the clinical fetal repercussions are often severe. Diagnosis is exclusively ultrasonographic and must be made as early as possible, emphasizing the importance of detecting chorionicity in twin pregnancy, in addition to serial ultrasonographic follow-up to track the development of the syndrome. Although there is still no well-established treatment protocol, endoscopic laser ablation of vascular anastomoses is considered the gold standard among the available therapeutic options. It has a high survival rate for at least one of the fetuses and low rates of neonatal neurological sequelae and can only be performed until the 26th week of pregnancy.

Effects of inter-twin vascular anastomoses of monochorionic twins with selective intrauterine growth restriction on the contents of placental mitochondria DNA.

BACKGROUND: Placental mitochondrial DNA (mtDNA) has been proposed to be an indicator for placental hypoxia. This study was designed to evaluate the effect of vascular anastomoses between monochorionic (MC) twins on placental mtDNA. METHODS: In this study, twin-twin transfusion syndrome (TTTS) treated with laser therapy and MC twins without TTTS (without laser therapy) resulting in two live babies were included in this study. The placental mtDNA fold changes (FC) between the small and large twins were analyzed using real-time quantitative PCR. TTTS twins with selective intrauterine growth restriction (sIUGR) are categorized as group 1, TTTS without sIUGR as group 2, MC twins without TTTS but with sIUGR as group 3, and MC twins without both TTTS and sIUGR as group 4. RESULTS: There were seven cases in group 1, eight in group 2, 26 in group 3, and 24 in group 4 cases. The placental mtDNA FC were significantly higher in group 1 (1.57 ± 0.9) compared to that of the group 3 (0.86 ± 0.6). CONCLUSION: In MC twin pregnancies with sIUGR, the placental mtDNA FC between the small and large twins are different between cases with and without inter-twin anastomoses. These findings suggest that the inter-twin anastomoses in the MC twins with sIUGR may provide rescue perfusion from the appropriate-for-gestational-age twin to the sIUGR one.

Comparison of Solomon technique with selective laser ablation for twin-twin transfusion syndrome: a systematic review.

OBJECTIVE: To compare the Solomon and selective techniques for fetoscopic laser ablation (FLA) for the treatment of twin-twin transfusion syndrome (TTTS) in monochorionic-diamniotic twin pregnancies. METHODS: This was a systematic review conducted in accordance with the PRISMA statement. Electronic searches were performed for relevant citations published from inception to September 2014. Selected studies included pregnancies undergoing FLA for TTTS that reported on recurrence of TTTS, occurrence of twin anemia-polycythemia sequence (TAPS) or survival. RESULTS: From 270 possible citations, three studies were included, two cohort studies and one randomized controlled trial (RCT), which directly compared the Solomon and selective techniques for FLA. The odds ratios (OR) of recurrent TTTS when using the Solomon vs the selective technique in the two cohort studies (n = 249) were 0.30 (95% CI, 0.00-4.46) and 0.45 (95% CI, 0.07-2.20). The RCT (n = 274) demonstrated a statistically significant reduction in risk of recurrent TTTS with the Solomon technique (OR, 0.21 (95% CI, 0.04-0.98); P = 0.03). The ORs for the development of TAPS following the Solomon and the selective techniques were 0.20 (95% CI, 0.00-2.46) and 0.61 (95% CI, 0.05-5.53) in the cohort studies and 0.16 (95% CI, 0.05-0.49) in the RCT, with statistically significant differences for the RCT only (P < 0.001). Observational evidence suggested overall better survival with the Solomon technique, which was statistically significant for survival of at least one twin. The RCT did not demonstrate a significant difference in survival between the two techniques, most probably owing to the small sample size and lack of power. CONCLUSION: This systematic review of observational, comparative cohort and RCT data suggests a trend towards a reduction in TAPS and recurrent TTTS and an increase in twin survival, with no increase in the occurrence of complications or adverse events, when using the Solomon compared to the selective technique for the treatment of TTTS. These findings need to be confirmed by an appropriately-powered RCT with long-term neurological follow-up.

Laser therapy for twin-twin transfusion syndrome in the absence of fetoscopically visible placental vascular anastomoses.

Fetoscopic laser photocoagulation (FLP) was performed at 22 weeks of gestation for a pregnancy complicated with twin-twin transfusion syndrome (TTTS) and an anterior placenta. However, vascular anastomoses could not be identified by the fetoscope. To dichotomize the circulation between the twins, the terminal ends of the paired artery and vein of the recipient twin were coagulated. In addition, a line was drawn with the laser connecting the dots, which had been coagulated. The Doppler waveform as well as the amniotic fluid volume of each twin normalized after the procedure. The twins were delivered by cesarean section subsequent to onset of labor at gestational week 30; the recipient twin weighed 1,350 g and the donor twin weighed 550 g. Both twins had a normal neurologic exam at 6 months of age. Patent placental vascular anastomoses could not be detected. This case demonstrates that vascular anastomoses in TTTS may not be identified by a fetoscope and that FLP to coagulate the entire vascular equator closer to the area of the recipient twin was effective in this rare situation.

'In parallel' interconnectivity of the dorsal longitudinal anastomotic vessels requires both VEGF signaling and circulatory flow.

Blood vessels deliver oxygen, nutrients, hormones and immunity factors throughout the body. To perform these vital functions, vascular cords branch, lumenize and interconnect. Yet, little is known about the cellular, molecular and physiological mechanisms that control how circulatory networks form and interconnect. Specifically, how circulatory networks merge by interconnecting 'in parallel' along their boundaries remains unexplored. To examine this process we studied the formation and functional maturation of the plexus that forms between the dorsal longitudinal anastomotic vessels (DLAVs) in the zebrafish. We find that the migration and proliferation of endothelial cells within the DLAVs and their segmental (Se) vessel precursors drives DLAV plexus formation. Remarkably, the presence of Se vessels containing only endothelial cells of the arterial lineage is sufficient for DLAV plexus morphogenesis, suggesting that endothelial cells from the venous lineage make a dispensable or null contribution to this process. The discovery of a circuit that integrates the inputs of circulatory flow and vascular endothelial growth factor (VEGF) signaling to modulate aortic arch angiogenesis, together with the expression of components of this circuit in the trunk vasculature, prompted us to investigate the role of these inputs and their relationship during DLAV plexus formation. We find that circulatory flow and VEGF signaling make additive contributions to DLAV plexus morphogenesis, rather than acting as essential inputs with equivalent contributions as they do during aortic arch angiogenesis. Our observations underscore the existence of context-dependent differences in the integration of physiological stimuli and signaling cascades during vascular development.

The third time is the charm--anastomosis between the celiac trunk and the left colic artery.

An atypical case of abdominal vasculature, found in a 58-year-old woman is presented. The multidetector computed tomography angiogram revealed a large tortuous anastomotic vessel between the stem of the celiac trunk and the left colic artery, supplying branches for the left colon and pancreatic body and tail. We propose a simple embryological explanation for the development of this aberrant artery--the longitudinal ventral anastomosis, which connects the precursors of principal visceral arteries in a loop-like manner, loses its direct communication with the superior mesenteric artery but maintains its continuity above and below this level. This variation could pose a problem for radiological interpretation and affect surgical approaches to the aorta, left colon, and the pancreas.

Laser coagulation of placental anastomoses with a 30 degrees fetoscope in severe mid-trimester twin-twin transfusion syndrome with anterior placenta.

OBJECTIVE: To assess outcome after fetoscopic laser coagulation (FLC) of placental vascular anastomoses with the 30 degrees fetoscope in mid-trimester severe twin-to-twin transfusion syndrome (TTTS) with completely anterior placenta compared with the regular 0 degrees fetoscope in TTTS with other placental locations. METHODS: This was a prospective study of 176 consecutive monochorionic twin pregnancies undergoing FLC for severe TTTS. Of these, 51 patients required use of the 30 degrees fetoscope (study group) and 125 placental locations permitted use of the 0 degrees fetoscope (controls). RESULTS: The two groups had very similar outcomes. The median gestational age at FLC in the study group vs. control group was 21.0 (range, 17.4-24.6) weeks vs. 20.6 (range, 15.9-24.6) weeks. Both fetuses survived in 58.8% (30/51) of study patients vs. 66.4% (83/125) of controls. At least one fetus survived in 84.3% (43/51) of study patients and 88.8% (111/125) of controls (P = 0.45). Study patients delivered at a median of 34.1 (range, 25.0-38.4) weeks and controls at 34.0 (range, 25.0-40.3) weeks' gestation. CONCLUSIONS: Use of a 30 degrees fetoscope for FLC in cases of technically challenging extensive anterior placentation is associated with an outcome that is very similar to that achieved when a 0 degrees fetoscope is used in cases of more favorable placental location.

The retroperitoneal anastomoses of the gonadal veins in human foetuses.

In the retroperitoneal space the gonadal veins form a collateral circulation that has a great clinical impact on sclerotherapy or surgical ligation of varicoceles. The aim of this study was to examine the communications of the gonadal veins (according to classification, frequency of appearance, gender and syntopic differences) in human foetuses of both sexes (71 males and 59 females) aged 4--6 months of intrauterine life. On the right side the most frequently were found the gonadal-periureteral anastomosis (23%) and the gonadal-perirenal anastomosis (22%). A gonadal-lumbar anastomosis on the right side appeared in 7% of cases. On the left side the most frequent (37%) was the gonadalperirenal anastomosis, more frequently occurring as an ovarian-perirenal anastomosis (48%) than as a testicular-perirenal anastomosis (29%). Gonadal-periureteral anastomoses were found in a quarter of cases. Gonadal-lumbar anastomoses were observed in 7% of individuals. On the left side the gonadal-mesenteric inferior anastomosis was specifically observed (21%) as an ovarian-mesenteric inferior anastomosis (24%) and a testicular-mesenteric inferior anastomosis (19%). The cross-communications between the right and left gonadal veins (7%) were more frequently as the bilateral testicular (9.7%) than as the bilateral ovarian one (3%). In female foetuses gonadal-perirenal anastomoses occurred with statistically greater frequency than gonadal-periureteral anastomoses (p<=0.05). The frequency of cross-communications of the gonadal veins was three times greater in male foetuses (p

Placental angioarchitecture in monochorionic twin pregnancies: relationship to fetal growth, fetofetal transfusion syndrome, and pregnancy outcome.

OBJECTIVE: We sought to correlate placental vasculature with fetal growth and outcome in monochorionic twins. STUDY DESIGN: Eighty-two patients with consecutive monochorionic pregnancies underwent biweekly ultrasonography for determination of fetal growth and well-being. After delivery, blinded placental injection studies delineated vascular anastomoses and territory share. Degree of balance in arteriovenous anastomoses equaled the number of arteriovenous anastomoses in one direction minus the number in the other. RESULTS: Pregnancies affected by fetofetal transfusion syndrome (n = 21) had numbers of arteriovenous and venovenous anastomoses that were similar to those in pregnancies without fetofetal transfusion syndrome but fewer arterioarterial anastomoses (P <.0001). Fetofetal transfusion syndrome occurred in 78% of pregnancies with >/=1 arteriovenous and no arterioarterial anastomoses. Birth weight discordancy correlated with placental territory discordancy (P <.0001) and the degree of balance in arteriovenous anastomoses (P =.004). The larger placental share twin had a greater growth velocity than its smaller placental share co-twin (P =.008) for all but one anastomotic pattern. Where arteriovenous anastomoses were aligned with the net venous outflow to the fetus with the smaller territory, co-twins had similar birth weights and growth velocities irrespective of placental share. Fetal survival was higher in pregnancies with an arterioarterial anastomosis (P =.01) but lower with a venovenous anastomosis (P =. 01). Survival of both fetuses was inversely associated with birth weight discordancy (P <.0001). CONCLUSION: Although interrelationships among the various types of anastomoses are complex, our data suggest that the placental territory share and the pattern of arteriovenous anastomoses influence fetal growth, that arterioarterial anastomoses protect against fetofetal transfusion syndrome, and that venovenous anastomoses reduce perinatal survival.

[Persistent trigeminal artery and its variant. Contribution of MRI and MR-angiography]. / La persistance de l'artere trigéminée et sa variante. Apport de l'IRN et de l'angio-RM.

We describe the magnetic resonance imaging and magnetic resonance angiography findings in 5 cases of persistent trigeminal artery, and in two cases of variant trigeminal artery. Six patients underwent complete four-vessel angiography, performed to depict other pathology. Magnetic resonance imaging and magnetic resonance angiography allowed in each case to visualize this artery and to precise its latero or intrasellar situation. The variant is not defined on conventional magnetic resonance imaging, but may be individualized on magnetic resonance angiography. In each case, identification of these persistent artery is crucial if surgery of sellar or gasserian region is planned.

Development of arteriovenous anastomoses in Rattus norvegicus species during the fetal period.

In this study carried out on the development of arteriovenous anastomoses (AVAs) in Rattus norvegicus species, the fetus was followed up 10 days after post coitum (pc). The sections obtained from the fetuses of 10-20-day rats were subjected to the usual processes for examination under the light microscope. Various staining processes were applied on the preparations and the simple and glomus types of AVAs determined in the mesenchyme of fetuses observed to birth every day. The regions with AVAs were then photographed by photomicroscopy and evaluated. From the 10-day embryo to birth, an increase in the smooth muscles in the wall structure of simple anastomoses was observed. It was however very difficult to follow up this increase in glomus anastomoses because the wall structure is more complicated. Their morphology was examined and compared with that in literature.

Anastomosis anómala entre las arterias hepática y mesentérica superior / Anomalous anastomosis between the hepatic and superior mesenteric arteries

Variaciones anatómicas en las arterias de las regiones hepática y peripancréatica han sido descritas, en el 34 por ciento de los pacientes sometidos a angiografías preoperatorias del tronco celiaco y de la arteria mesentérica superior. Estas variaciones pueden complicar seriamente algunas intervenciones, como la cirugía laparoscópica, al alterar la disposición de los elementos en el hilio de los órganos; o hacer impracticable algunos actos quirúrgicos complejos, como el transplante hepático o la resección del páncreas. En este trabajo, presentamos un raro caso de anastomosis entre las arterias hepática y mesentérica superior. Este vaso anómalo, de trayecto tortuoso, dispuesto detrás del cuello del páncreas, mide 21 cms. de largo, presenta un calibre irregular y en la parte inicial de su trayecto da origen a las ramas gastroepiploica derecha y pancreático-duodenal superior. En el texto se discuten las posibles causas embriológicas que explican esta variación anatómica

Subpleural vascular anastomoses in lungs of human fetuses.

Studies were performed on 35 left lungs, originating from human fetuses, who died at the age of 20 to 29 weeks of fetal life, using corrosion casts, microangiographic technique or methyl salicylate induced translucency. A typical network of subpleural vessels was observed, which joined pulmonary arteries and veins and formed direct anastomoses between pulmonary arteries and veins within pulmonary acini of the subpleural layer.

Persistent hypoglossal artery in the fetus.

The hypoglossal artery in a human fetus studied by post mortem angiography and microdissection is described. In contrast to the fetal form of the trigeminal artery which differs from the adult form by possessing branches supplying the pons and anastomotic branches to the cerebellar and internal auditory arteries, there were no major anatomical differences between the fetal and the adult form of the hypoglossal artery. The incompetence of the vertebral arteries in the presence of a hypoglossal artery is also emphasized.

Persistencia de la arteria trigeminal primitiva; reporte de un caso diagnosticado por angiografía carotídea

De los tres sistemas de anastomosis entre la carótida y la que hay en el embrión: la acústica, la trigeminal y la hipoglosa, la segunda habían reportado 134 casos en la literatura mundial. El uso cada días más difundido de la arteriografía carotídea, ha permitido la visualización más frecuente de esta arteria que antiguamente era patrimonio casi exclusivo del anatomista. Su visualización constituye un hallazgo ya que no ocasiona de por sí sintomatología alguna, no obstante es útil el detectar su presencia en la planificación de determinadas técnicas quirúrgicas (AU)