Reliability of society of fetal urology and Onen grading system in fetal hydronephrosis.

Both the SFU and Onen grading systems showed good intra-observer agreement in prenatal ultrasonography. The inter-observer agreement was decreased in SFU grades 1 and 3 and Onen grades 2 and 3. Therefore, more focus should be given to SFU grades 1 and 3 and Onen grades 2 and 3 for trainees.