Perfusão Arterial Invertida em Gémeos

A perfusão arterial invertida em gémeos foi descrita pela primeira vez em 1533 por Benedetti. Esta patologia também é conhecida como TRAP (Twin Reversed Arterial Perfusion) ou monstro acárdico. É uma patologia que ocorre na gravidez múltipla monocoriónica caracterizada pela presença de um gémeo dador e outro receptor, anómalo, muitas vezes sem estrutura morfológica definida. É uma situação rara (1/35000 partos) mas grave, podendo ocorrer a morte do gémeo normal em cerca de 50 (¹,²,³)- 75% (¹,²) dos casos, consoante as séries consultadas. Foi efectuado um estudo retrospectivo dos casos de gémeos acardicos vigiados na Consulta de Gravidez Múltipla e no Centro de Diagnóstico Pré-Natal da Maternidade Dr. Alfredo da Costa, entre os anos de 1994 e 2002. Num total de 597 gravidezes múltiplas, 120 caracterizadas como monocoriónicas, foram diagnosticados três casos.

Resultado do Obstétrico de Gravidezes Gemelares Resultantes de Fecundação in Vitro, Microinjeção e Estimulação da Ovulação em Comparação com Espontâneas

Introduction: Uncontrolled studies suggest that twins conceived by in vitro fertilization have increased rates of preterm birth and low birth weight and would warrant increased antenatal monitoring. The objective of this study was to compare the obstetric outcome of twin pregnancies conceived by in vitro fertilization or intracytoplasmic sperm injection (IVF/ICSI) and ovulation induction with those conceived spontaneously. Methods: All twin deliveries achieved by IVF/ICSI (n=235) and ovulation induction (n=68) from September 1994 through December 2010 were evaluated. Both groups and an additional control group who conceived spontaneously (n=997) and was delivered during the same time period were compared with each other. Results: In univariate analysis, patients who conceived with the assistance of IVF/ICSI had a significantly higher risk of being older (p=0.01), nulliparous (p=0.01), having hypertensive disorders (p=0.012), gestational diabetes mellitus (p=0.031), cesarean section (p=0.008) and lower gestational age at birth, compared with the control group. Newborns had similar birthweights in all groups (2229±544g; 2102±619g; 2251±553g). Spontaneous pregnancies had a higher risk of being monochorionic 38.4% versus 16.2% and 10.2% (p=0.01). Multivariate analysis however showed that patients who conceived with the assistance of IVF/ICSI only had a higher risk of gestational diabetes (OR=1.91,95%CI 1.168-3.120; p=0.01). Conclusions: Our study shows that twin pregnancies conceived with the assistance of IVF/ICSI had a higher risk of gestacional diabetes and a lower gestacional age at birth. Birthweights were similar, as was the incidence of perinatal death, low birth weight infants, and congenital malformations.

Partial Rhombencephalosynapsis.

Clinical history - A 4-year-old boy, born prematurely at 29 weeks (twin pregnancy), with periventricular leukomalacia and epilepsy underwent brain MRI. Neurological examination showed severe developmental retardation with axial hypotonia, spastic tetraparesis and convergent strabismus. Imaging findings - Cranial MRI revealed typical aspects of partial rhombencephalosynapsis with vermian hypoplasia, midline fusion of the cerebellar hemispheres and transversely oriented folia and fissures. There was also mild dilatation and dysmorphism of the ventricular system, the septum pellucidum was absent, the hippocampi were malrotated and had vertical orientation and additional finding of associated periventricular cystic leukomalacia. Discussion - Rhombencephalosynapsis (RS) is a rare congenital defect of the cerebellum classically characterised by vermian agenesis or hypogenesis, fusion of the hemispheres, and closely apposed or fused dentate nuclei. It is now considered to result from an absence of division of the cerebellar hemispheres, following an insult between the 28th and 44th day of gestation (i.e., before the formation of the vermis). Other features have also been described such as fusion of the thalami and cerebral peduncles, malrotated hippocampi, corpus callosum agenesis, hypoplastic chiasm, absence of the septum pellucidum, ventriculomegaly, agenesis of the posterior lobe of the pituitary and cortical malformations. Musculoskeletal, cardiovascular, urinary tract, and respiratory abnormalities have been reported. Typical symptoms consist of swallowing difficulties, delayed motor acquisitions, muscular hypotonia, spastic quadriparesis, cerebellar signs including dysarthria, gait ataxia, abnormal eye movements, and seizures and hydrocephalus. The major MRI signs consist of fused cerebellar hemispheres, with absent or hypoplastic vermis, narrow diamond-shaped fourth ventricle and fused dentate nuclei. In a minority of cases, partial RS has been identified by MRI, demonstrating the presence of the nodulus and the anterior vermis and absence of part of the posterior vermis with only partial fusion of the hemispheres in the inferior part. Other cerebellar malformations involving vermian agenesis or hypoplasia include the Dandy–Walker continuum, Joubert syndrome, tectocerebellar dysraphy or pontocerebellar hypoplasias, and are now easily distinguished from RS by both brain MRI and morphology.

Prospective Risk of Intrauterine Death of Monochorionic-Diamniotic Twins

OBJECTIVE: The purpose of this study was to calculate the prospective risk of fetal death in monochorionic-diamniotic twins. STUDY DESIGN: We evaluated 193 monochorionic diamniotic twin pregnancies that were followed and delivered after 24 weeks. Surveillance included cardiotocography and sonography performed at least once weekly. The prospective risk of fetal death was calculated as the total number of deaths at the beginning of the gestational period divided by the number of continuing pregnancies at or beyond that period. RESULTS: The fetal death rate was 5 of 193 pregnancies (2.6%; 95% CI, 1.1, 5.9); the prospective risk of stillbirth per pregnancy after 32 weeks of gestation was 1.2% (95% CI, 0.3% - 4.2%). CONCLUSION: Under intensive surveillance, the prospective risk of fetal death in monochorionic-diamniotic pregnancies after 32 weeks of gestation is much lower than reported and does not support a policy of elective preterm delivery.

Perinatal Outcome and Change in Body Mass Index in Mothers of Dichorionic Twins: a Longitudinal Cohort Study

We used a prospective cohort to analyze the effect of change in BMI rather than change in weight, in mothers carrying dichorionic twins from a population that did not receive any dietary intervention. A total of 269 mothers (150 nulliparas and 119 multiparas) were evaluated. The average change (%) from the pre-gravid BMI was 7.2+/-6.1, 17.4+/-8.2, and 28.7+/-10.8, at 12-14, 22-25, and 30-34 weeks, respectively, without difference between nulliparas and multiparas. The comparison between maternities below or above the average change from the pregravid BMI failed to demonstrate an advantage (in terms of total twin birthweight and gestational age) of an above average change from the pregravid BMI, even when the lower versus upper quartiles were compared. Our observations reached different conclusions regarding the recommended universal dietary intervention in twin gestations. A cautious approach is advocated towards seemingly harmless excess weight gain, as normal weight women may turn overweight, or even obese, by the end of pregnancy, and be exposed to the untoward effects of obesity on future health and body image.

Morte Fetal de um Gémeo. Que Problemas para o Gémeo Sobrevivente?

Na gravidez bigemelar, a morte de um dos fetos no segundo e terceiro trimestre é uma complicação rara, variando a taxa de incidência entre 2,6 e 6,8%. Este acontecimento determina um aumento das taxas de morbilidade e mortalidade perinatal para o gémeo sobrevivente, especialmente em gravidezes monocoriónicas, quando a morte fetal é devida à síndroma de tranfusão feto-fetal. Para alguns autores o atraso de crescimento intrauterino e a prematuridade são os principais factores de risco para o aumento da morbilidade e mortalidade do gémeo sobrevivente. A patofisiologia de instalação dos distúrbios cerebrais no gémeo sobrevivente após a morte do feto irmão não está definida, nem o intervalo de tempo que medeia entre a morte e o estabelecimento das lesões. Também não existe um protocolo definitivo de seguimento destas gravidezes e, posteriormente, do gémeo sobrevivente. No período de 1 de Setembro de 1994 a 31 de Dezembro de 1998, foram seguidas, na consulta de Gravidez Múltipla da Maternidade Dr. Alfredo da Costa, 235 gravidezes bigemelares. Em nove casos (3,8%) ocorreu morte de um dos fetos com idade gestacional acima das 13 semanas. Em cinco das nove gravidezes foi conhecida a causa de morte, quatro das quais foram atribuídas à síndroma de tranfusão feto-fetal. A taxa de prematuridade do gémeo sobrevivente foi de 44,4% (4/9) e a de mortalidade de 11,1%(1/9). A taxa de morbilidade neonatal foi de 62,5% (5/8), na maioria dos casos por complicações inerentes à prematuridade. A taxa de morbilidade neurológica foi de 37,5% (3/8). A taxa de lesões neurológicas major foi de 25% (2/8) e ocorreu em recém-nascidos de termo. A síndroma de transfusão feto-fetal, como causa de morte fetal, associou-se aos casos com pior prognóstico no que se referiu ao gémeo sobrevivente.O crescimento do gémeo sobrevivente parece depender das lesões provocadas pela morte do feto irmão. Os autores finalizam com uma proposta de atitudes obstétricas e pediátricas em relação ao gémeo sobrevivente.