OK, well. Now we've been to see the experts and their boss. (And I've encountered the most amazingly convulted route to a car park I've ever seen, but that's another story entirely). And the consensus is that what originally appeared to be a dilated kidney is actually a collection of fluid (a urine bubble) at the outside of some kidney tissue, which is not fully developed. At some point during the development of that kidney & the vessels associated with it, a blockage (most likely) occurred, and it resulted in the malformation of the kidney. It was, at some point, at least, producing some urine (hence the bubble), but probably isn't functioning much anymore, if at all.

What does this mean? Well, there's no danger to the baby in utero (provided nothing happens with the other kidney, which is highly unlikely), and it's not even an emergency once he's born. The urine bubble should disperse itself gradually without intervention. At some point after he is born, they'll do some scans, possibly some x-rays, maybe some other diagnostic tests, with the purpose of seeing if the right kidney has any function at all, if it does, how much, and if there's any chance of it presenting a danger to the baby, in terms of infection or interference with other functions. It's possible that if they decide it poses a risk, they'll want to remove it eventually. The head of the department (the uber-specialist) says that he thinks that it's unlikely that the baby will have much functionality in the right kidney, but it's not something they can tell for certain until after he's born.

So, that's that. Apparently, it's officially known as a "dysplastic kidney" with some "perinephric fluid collection, likely to be a urinoma". In people speak, that's a kidney that's malformed, with a urine (or possibly other fluid, but most likely urine) bubble next to it. Anyway. They'll do a follow up scan in about 6 weeks time, just to check on stuff, and towards the end of the pregnancy we'll get to meet some of the paediatric urology specialists, who will be the ones dealing with him once he's born.

It's still not really a cause for worry (and anyway, there's nothing we can do about it now). I think that's about all they said, except that there's no way of telling for certain precisely when or why the problem occurred. But there's no reason to think that anything will happen with the left - this does not make it more likely that the left will have problems.

And the other good news is that there's nothing wrong with anything else - the rest of the baby - heart, brain, limbs, genitalia, and so on and so on are all perfectly normal - this is just one of those little glitches that sometimes happen. While it's somewhat frustrating to know about it now and therefore have it hanging over you, it's actually a good thing that they know about it before he's born, as they can then make sure that there is no potential for further damage, problems, infection, and so on. Without this kind of scanning, this kind of problem might not show up until much later, perhaps as a series of chronic urinary infections or something, which could potentially damage the other kidney, so knowing in advance that they'll need to check the right kidney & keep an eye on it and/or remove it if it looks like it might be a problem is a positive thing. Best to be prepared, as any boy scout will tell you :)