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

Abstract

ObjectiveTo evaluate the reliability of the Society for Fetal Urology (SFU) and Onen grading systems for fetal hydronephrosis inprenatal ultrasound according to the level of experience of the examiner. MethodsWe reviewed the prenatal ultrasound images of 146 fetuses (292 kidneys) that were diagnosed as havinghydronephrosis between January 2005 and December 2014. One expert and two trainees assessed the prenatalrenal ultrasound images using the SFU and Onen grading systems. The three examiners independently assessedeach ultrasound image with both grading systems and reassessed the same images after 7 to 14 days. Cohen’s kappastatistic was used to estimate intra- and inter-observer reliability in prenatal ultrasound images according to traininglevel. ResultsThe intra-observer reliability of the SFU grading system (κ 0.873–0.945) showed almost perfect agreement and that ofthe Onen grading system (κ 0.749–0.913) showed substantial to almost perfect agreement. The overall inter-observerreliability of the SFU grading system (κ 0.620–0.825) showed substantial to almost perfect agreement and that of theOnen grading system (κ 0.618–0.724) showed substantial agreement. The weighted kappa value of inter-observeragreement was 0.223 to 0.400 for SFU grade 1 and 0.064 to 0.346 for SFU grade 3. For Onen grading, the interobserveragreement was 0.012 to 0.214 for grade 2 and 0.193 to 0.334 for grade 3. ConclusionBoth the SFU and Onen grading systems showed good intra-observer agreement in prenatal ultrasonography. Theinter-observer agreement was decreased in SFU grades 1 and 3 and Onen grades 2 and 3. Therefore, more focusshould be given to SFU grades 1 and 3 and Onen grades 2 and 3 for trainees.