Frequently Asked Questions

Elongated renal length is of secondary importance. Kidney length is not a factor in SFU grading, but it is common that kidneys with clinically significant obstruction and SFU Gr 3 HN show lengths above the range of normal. In addition almost all kidneys with SFU Gr 4 HN show elongate growth.

No, the sizes of the renal pelvis and calyces by themselves do not correlate with clinically significant obstruction.This is because obstruction seems to be correlate with the observation of uniformly dilated minor calyces, therefore:

• Noting a prominent extrarenal pelvis, without minor calyceal dilation, is not a sign of obstruction, and...

• Noting prominent major calyces, without minor calyceal dilation, is not a sign of obstruction.

No, the child's state of hydration does not influence SFU grading.

The grading method does not specify the state of hydration, so it is possible that a child will undergo ultrasonography one day and be relatively under hydrated and at another session be over hydrated. As this variability has not been researched, your own empiric judgments on hydration would apply. It is common sense, if you are performing the ultrasound in your office (IOUS), that you simply ask the family if the child is drinking normally.

SFU Grading asks for the bladder not to be over full, As it is recognized that an overfull bladder may impact on the extent of renal and ureteral dilation, waiting for the infant to void permits an opportunity to reassess the state of renal dilation. Oftentimes, pressure applied over the bladder by the ultrasound transducer will initiate a void and expedite making this comparison.

No, several examiners may perform one exam. As you review ultrasounds performed in a radiology department, be aware that the images may be a synthesis of pictures taken by more than one sonographer and/or radiologist. Because of this the image sequence may appear illogical. If this circumstances arises, consider inquiry if multiple examiners performed the test.

No, the position of the child is not stipulated in SFU grading.

Grading hydronephrosis requires a representative long view of kidney. Imaging kidneys with the child supine may restrict this panorama view as the kidney could reside under the rib cage and so elude such imaging. Having the child rotate into the prone position typically provides good long views without the obstacle of the ribs.

No, the grading method is designed to address unilateral hydronephrosis.

As the grading method was developed to address the most common clinical presentation, that of unilateral renal obstruction, cases with bilateral obstruction are not suitable for grading. It is not uncommon that in such cases, there is really a "worse" side which presents pathophysiological stresses on the "other" side is required to drain an increased urine output and so shows a higher grade of hydronephrosis than actually is present.

No, SFU grading does not apply to children with significant reflux (>Gr 3).

As the grading method was developed to address the most common clinical presentation, that of unilateral renal obstruction, cases with significant reflux are not suitable for grading.

No, SFU grading does not apply to children who are post urological surgery or older than 18 months of age?

As the grading method was developed to address the most common clinical presentation, that of surgical decision making in children with significant hydronephrosis, once children have had surgery, the principles of SFU grading do not apply.

SFU grading is validated for infants and not for older children.

No, specific patterns of hydronephrosis are not suitable to SFU grading of hydronephrosis: duplication anomalies, Prune belly syndrome, posterior urethral valves, spinal dysraphism.

The SFU grading was developed because the natural history of children with significant unilateral hydronephrosis in a single moiety kidney was unknown. This natural history is likely different from that of children with the specific pattern of renal duplication such as ectopic ureter or ureterocele. In these instances, the extent of renal dilation is not a major factor in clinical decision making.

In such cases it is reasonable to apply the grading method as a means to create a mental image as a thumbnail. Such that the pattern of SFU Gr 3 hydronephrosis might be noted in the lower pole of an ectopic ureter with grade 4 reflux, or a such a pattern might be noted in a child with spinal dysraphism with uncontrolled spastic bladder causing hydronephrosis. The grades of these thumbnail captures are not utilized in clinical decision making.

SFU grading applies to primary megaureters as follows: The natural history of megaureters seems to correlate to the SFU Grades of both the kidney collecting system and width of the pelvic ureter. Such kidneys are assessed by the SFU Score (sum of kidney and ureter grades).

Yes, they may not always be evident because of variations in development of the pyelocalyceal collecting system. In these instances imaginative intuition guides grading as show in these examples.

This application regards the meaning of these commonly interchanged terms as:

• Stasis - slow drainage which clinical judgment triages to surgery or not.

• Renographic UPJ Obstruction - stasis found in an otherwise well child in which the clinician judges that if left untreated, the child is likely to develop illness or loss of renal function.

• UPJ Obstruction - renographic obstruction in the face of urological illness such as pyelonephritis in the affected kidney.

No, grading of hydronephrosis is one piece of clinical information which the health professional will utilize to extend clinical care.