Hello,
I am very sorry for what had happened to you. It was very unfortunate. Fluid in the fetal abdomen would definitely be visible with a high resolution sonogram and so is the fluid collection elsewhere. In today's world where operations are performed on an unborn child, it is very unfortunate that such things still happen. The organ enlargement raises suspicion of 'Hydrops Fetalis' and this should be excluded so as to take precautions in future. Other rare genetic diseases are also a possibility. If, there was no known organomegaly earlier, the sudden death may have been caused due to a tight cord around the neck, placental separation, severe infection etc. Hope this helps.