Spina bifida can be diagnosed in unborn children. You already mentioned some of it. You are an expert in fetal surgery and in utero endoscopic surgery. Fetal surgery can be done on an unborn child with spinal bifida, which, you already mentioned, doesn't remove the spina bifida. Nevertheless, there are some indications for fetal surgery for spina bifida. Could you please summarize the benefits and risks of doing the endoscopic fetal surgery in situations where spina bifida is discovered before the birth of a child? So the advantage of intrauterine surgery for spinal bifida is that you prevent, on top of the malformation, the deleterious effect of the aggressivity of amniotic fluid on the exposed spine. Because the fetal spine is not protected by the bones nor the skin. So the amniotic fluid is quite aggressive on this spine. So it worsens the lesion and the effect. It's called the two-hit hypothesis. One is malformation. The second is the aggressiveness of the toxicity of the amniotic fluid on the spinal lesion. So you help by protecting the spinal lesion.

A good proportion of these babies do not need to be reoperated after birth, or sometimes they have a tethered spinal cord. And then it's a smaller operation than the whole Spina Bifida. So it's mainly to prevent that amniotic fluid-related morbidity. And that's probably why the effect of intrauterine surgery is not that major compared to postnatal surgery. But that helps. So for women who want to carry on with the pregnancy, which is not considering termination of pregnancy, that fetal surgery can help. The downside is the risk of prematurity because of the rupture of membranes. As for all endoscopic surgery, mainly, and therefore risks of prematurity. But prematurity for spinal bifida is kind of an open question. Apart from extremely premature delivery, where this is life-threatening, if that prematurity is moderate, it might be that this has a positive effect because there is less exposure of the baby to the amniotic fluid also. So you know that the relationship between all these is not very clear. But basically, you want to go ahead with your pregnancy. And you want to gain that little benefit, which is for 15 percent of the fetuses seem to benefit from intrauterine surgery. In contrast, about five to 10% of fetuses with spina bifida do not benefit from fetal surgery and get worse. So the balance is quite thin to find. What is the typical timing for the spina bifida surgery as in relation to the pregnancy? How much time usually passes before the delivery of baby after fetal endoscopic surgery? For all fetal surgery, there are two phases. Too early, and you get a very high rate of complications like rupture of membranes. So you have to do fetal endoscopic surgery about mid-pregnancy, between 20 and 25 weeks of pregnancy, of gestation is the right time. And that is true for all surgery. That's when the uterus is more tolerant of the aggression of the instruments. And that's when also the lesions are not that irreversible, probably, or not yet at a stage where no improvement can be expected. It will not make sense to operate on a fetus at 30 weeks of pregnancy, for example, for any fetal surgery. It is better to deliver the baby or the babies and do surgery after birth or just save them from Twin to Twin transfusion, for example. So then the attempt is to carry a pregnancy for another essentially ten weeks. Yeah, so that's what you expect a good two months in utero to grow, mature, and not be exposed to the lesions. Yeah. Does the pregnancy care after uterine surgery and fetal surgery differ significantly in those ten weeks. So what is the average? No, usually, that's an advantage of endoscopic surgery over open uterine surgery. If you do open surgery, there's no other way than Cesarean section, even if this woman gets into labor very early in gestation. Whereas if you operate endoscopically, she can deliver normally or vaginally at least anytime. And the care is not different. So you don't have to stay continuously in the hospital. You could be at home, doing a usual obstetrical follow-up? Not when the fetal endoscopic surgery is a one-shot thing. If you were thinking of what we were discussing about diaphragmatic hernia with a balloon that obstructs the trachea, then this baby cannot be born anywhere. The baby has to be born somewhere, either ideally after removing the balloon in utero. Or it is required to remove the balloon at birth by a very experienced team. So that's a different ballgame. But the spina bifida baby could be born in a back garden, that's not a problem, which might be an advantage for developing countries because this is a global problem. And in some countries where postnatal surgery of this condition exposes to perinatal infection before and after surgery after birth. It might be a good thing that these babies are operated on before they are born. That's a very important point. Thank you.