Hydronephrosis (grading)

Grading systems of hydronephrosis have been devised to communicate the degree of upper collecting system dilatation. The most common system used (Society of Fetal Ultrasound, SFU) was originally designed for grading neonatal and infant hydronephrosis:

  • 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

Hydronephrosis grading systems (including the SFU) are controversial in terms of their intra-rater and inter-rater reliability.

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Article information

rID: 26383
Synonyms or Alternate Spellings:
  • Hydronephrosis grading
  • Grading of hydronephrosis

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Cases and figures

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    Case 1: severe left hydronephrosis
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