Hydronephrosis found on 34 week ultrasound

At my 34 week ultrasound, it was found that one of my baby’s kidneys is slightly enlarged. The OB said the upper range of normal is 7mm and his measured 9mm. Everything seemed fine on the anatomy scan at 20 weeks so I’m worried that it’s suddenly showing up now.

She said my fluid is perfect which means he is urinating, so it will likely self resolve.

She still referred me to MFM and said he will likely need another ultrasound before being discharged from the hospital.

Has anyone else had a normal 20 week scan but then have hydronephrosis show up in the third trimester?

I know every case is different and that this is super common but I’m trying not to spiral.