The grading system of hydronephrosis developed by the Society of Fetal Urology (SFU) was devised to assess the degree of hydronephrosis. This particular system is thought to be the most common in use and was originally designed for grading neonatal and infant pelvicalyectasis:
-
grade 0
- no dilatation, calyceal walls are apposed to each other
-
grade 1 (mild)
- dilatation of the renal pelvis without dilatation of the calyces (can also occur in the extrarenal pelvis)
- no parenchymal atrophy
-
grade 2 (mild)
- dilatation of the renal pelvis (mild) and calyces (pelvicalyceal pattern is retained)
- no parenchymal atrophy
-
grade 3 (moderate)
- moderate dilatation of the renal pelvis and calyces
- blunting of fornices and flattening of papillae
- mild cortical thinning may be seen
-
grade 4 (severe)
- gross dilatation of the renal pelvis and calyces, which appear ballooned
- loss of borders between the renal pelvis and calyces
- renal atrophy seen as cortical thinning
All hydronephrosis grading systems are controversial in terms of their intra- and interobserver reliability 4.