M. Sanz Cortes

OP11.06: Do placental and amniotic membrane pathological changes occur following open and fetoscopic neural tube defect (NTD) repair?: Short oral presentation abstracts

one showed a fluctuant colour, between bright red and dark purple (bidirectional flow), which is rare in this type of anastomoses that usually have unidirectional flow. Results: In 9 of the 10 cases, there was intrauterine demise of the sick twin within the next 4 weeks after surgery. The changing colour in the AV anastomosis which is supposed to be unidirectional, was due to the low central blood pressure of the premortem small twin which turns into a low vascular pressure in the chorionic arterial branch too low to overcome the pressure of the chorionic vein branch of the normal twin at the level of the AV anastomosis. Conclusions: MCDA twin pregnancies complicated with a severe sFGR type II with no superimposed TTTS and that showed during Fetoscopic surgery a fluctuant change of colour at the level of an AV anastomosis had a high mortality rate of the small twin.

Re: Diffusion‐weighted magnetic resonance imaging of the fetal brain in intrauterine growth restriction. O. J. Arthurs, A. Rega, F. Guimiot, N. Belarbi, J. Rosenblatt, V. Biran, M. Elmaleh, G. Sebag and M. Alison. Ultrasound Obstet Gynecol 2017; 50: 79–87.

This retrospective study used diffusion-weighted magnetic resonance imaging (DWI) to compare fetal brain microstructure at around 30 gestational weeks between a cohort of 30 severely compromised fetuses with growth restriction (FGR) and a group of 24 normal controls. Arthurs et al. found that, compared with controls, FGR fetuses had lower apparent diffusion coefficients (ADCs), which reflect water diffusivity within a tissue, in their frontal white matter, thalami, centrum semiovale and pons. They also detected that the frontal–occipital ADC ratio was lower in FGR fetuses than it was in controls. These changes were interpreted as indicating delayed brain maturation in the FGR fetuses. Two of the FGR cases underwent termination of pregnancy and the autopsy results showed signs of hypoxia-related brain injury. One FGR case suffered spontaneous demise and signs of acute neuronal anoxia were observed on pathological analysis. Of the 26 FGR cases that were liveborn, 11 were followed up postnatally, presenting with normal transcranial head ultrasound examination in all cases. In three of these cases, magnetic resonance imaging (MRI) was performed at term-equivalent age, showing normal brain anatomy, and ADC values were normal in two and increased in one case. Eleven cases were assessed for neurodevelopmental outcome at a mean age of 4.8 years; seven showed normal neurological development, three had significant neurological delay and one had developmental/learning difficulties. This study aimed to detect brain differences that are not detected on standard anatomical MRI sequences, in fetuses exposed to severe forms of placental insufficiency. The rationale was based on the notion that growth-restricted fetuses with significant Doppler abnormalities are exposed to a hypoxic environment and might be expected to be developing in acidotic conditions1. In this scenario, there could be ongoing processes of brain injury that, while not yet evident as structural abnormalities, may be detected as a restriction in the diffusion of water molecules within the brain parenchyma. One of the initial processes of brain ischemia is cellular edema, which could be responsible for such increased restriction. As an established method for the investigation of microstructural characteristics in different conditions involving suboptimal fetal growth2 and in cases of neonatal hypoxia3, DWI is an appropriate technique for the assessment carried out in this study. It has been reported that DWI can reveal hypoxic ischemic brain injury at an earlier stage than can conventional MRI in asphyxiated neonates4. In neonates, it has been proposed that ADC could have additional diagnostic value, especially in cases with diffuse lesions that may remain below the threshold of visual detection. Moreover, it has been shown that in neonates with hypoxic ischemic damage and an apparently normal brain, ADC values during the neonatal period could predict developmental outcome at early school age3. Moreover, fetal DWI feasibility studies and ADC normative data in the second and third trimesters of pregnancy have been reported. Arthurs et al. focused this study at the most severe end of the FGR spectrum, selecting fetuses with an estimated fetal weight (EFW) < 3rd centile, abnormal uterine artery Doppler and absent or reversed end-diastolic flow in the umbilical artery. Consistent with these inclusion criteria, birth weights in this group were < 1st centile in 79% of the cases. It is well established that fetuses showing such signs of deterioration are, as expected, acidotic and therefore represent a good model in which to test their hypothesis. The limitations of this study should be borne in mind. A significant proportion of the controls could be at risk for adverse neurodevelopmental outcome, including five cases with unior bilateral ventriculomegaly < 12 mm, four with bilateral clubfoot, two with bilateral cleft lip, two with isolated polyhydramnios and two whose mothers had an indication with possible consequences for fetal cerebral development (such as systemic lupus erythematosus or undergoing immunosuppressive therapy). It is also unknown whether they selected only control fetuses with EFW > 10th centile. The lack of a ‘healthy controls’ group may constitute a significant drawback in the methodological design of this study, as FGR is compared against a group with potential microstructural anomalies secondary to their underlying conditions. Regarding the postnatal developmental assessment, their attrition rate is high for neonates and infants that were born at such an early gestational age. Moreover, it is unknown which perinatal complication (extreme/moderate prematurity or hypoxia) was the predominant cause that led to the neurological deficits encountered in some of the FGR