Hi, I just wanted to reply as I was in this situation a few months ago. Baby had dilated kidneys at the 20 week scan, and we were referred to fetal medicine where they found she had duplex kidneys and a uterocele in the bladder that was causing the swelling. They performed a (truly incredible!) procedure in-utero to puncture the uterocele.
Follow-up scans in my pregnancy showed a reduction in the swelling - the lower kidneys went back to normal measurements, and there was no scarring on the kidneys. But even so, I was in an absolutely terrible state while all of this was happening, it honestly felt like one of the most scary and challenging moments of my life and I was very anxious for the rest of my pregnancy.
But then our beautiful daughter was born a few weeks ago and she is thriving! She had a blood test to check her kidney function at birth which was normal, and will have another scan with the paediatric urology team to check on her kidneys and see if she needs another (minor, keyhole) operation. But I’m not worried about this at all now, even if this is needed! She’s on prophylactic antibiotics to make sure she doesn’t get an infection, but will come off these as soon as they can see it’s safe to.
So this is all to say that, even in my daughter’s much more rare case, where a procedure was needed in the pregnancy, it has all turned out fine!
The more people my husband and I speak to, the more people we hear of others having similar issues (with kidney issues/swelling) at scans and it turning out not as scary as it first seemed. My midwife even told me that she’d seen two other women recently whose babies were found to have a duplex kidney in a scan and their babies were completely fine. The scans are so good nowadays I think they’re finding these issues more and more. And the treatment we’ve received from the NHS has been amazing.
Sending a huge hug and wishing you all the very best.