Hydronephrosis but no stones?

A few weeks (maybe longer) ago I had an episode of severe pain and peeing visible blood.

Went to hospital and given antibiotics for a uti, although the dip test came back negative for nitrites and the lab test also came back negative.

Today I had a scan of my kidney which showed mild hydronephrosis but no stones.

I don’t have a doctors appt to discuss this yet as doc will contact me once they receive scans.

Is it possible this swelling is due to a stone I passed weeks (maybe months?) ago? Any experiences? Ofc will not take anything here as medical advice just wanting to hear experiences :)