A little bit of bad news at 20 weeks scan...

So yesterday I had my 20 week anatomy scan and today I got an email from my doctor saying that the baby looks healthy, however one of the kidneys was slightly enlarged. I know this could be a marker for Down syndrome but we had all that testing and it came back negative for that. So does anyone know what it could possibly be? Or has been through the same thing? Anything would help me right now since my doctor is now out of town for 2 days and I just want some kind of information 🙏🏻