Good day! The baby is one month old, on ultrasound of the kidneys they…

Good day! The baby is one month old, on ultrasound of the kidneys they found that the Chalice-lochanic system is enlarged on the right kidney and there's also a small dispersed mass in it. Urine analysis is good. The baby is breastfed. This morning he didn't go to the toilet for a little while, only just now went a bit more and then a bit less. He ate as usual. Has anyone encountered something like this?