The document discusses the significance of fetal hydronephrosis, a common congenital condition identified via antenatal ultrasonography, which can indicate conditions such as ureteropelvic junction obstruction that may require surgical intervention. A grading system for hydronephrosis in fetuses is established, highlighting that grades I and II may be benign, while grades IV and V generally necessitate surgery. It emphasizes the need for careful evaluation and monitoring of significant dilatations to prevent permanent kidney loss.

1. Dr/Ahmed Bahnassy
Consultant radiologist
Riyadh Military Hospital

2. Importance of the finding
• Most common congenital condition
discovered by antenatal US.
• ultrasonography enables us to detect the
correctable cause of hydronephrosis, such
as ureteropelvic junction obstruction.
• Failure of recognizing those needing
surgical intervention will result in
permanent loss of the kidney.

3. Fetal hydronephrosis Detection
• Grignon et al developed a grading system for hydronephrosis in
fetuses of 20 weeks gestation or greater in relation to their postnatal
findings.
• Grade I dilatations (AP renal pelvic diameter up to 1.0 cm) were
described as normal and physiologic because none of the affected
patients required surgery after birth.
• Grade II (>1.0–1.5 cm) and grade III (>1.5 cm with slight dilatation of
calices) dilatation was termed intermediate hydronephrosis; 50%
required postnatal surgical intervention.
• All patients with grade IV dilatation (>1.5-cm pelvis, moderate
dilatation of calices, no cortical atrophy) or grade V hydronephrosis
(>1.5-cm pelvis, severe caliceal dilatation, atrophic renal cortex)
required surgery.
• Their work suggests that one should be concerned with pelvic
dilatations greater than 10 mm particularly if there is associated
calyceal dilatation and loss of cortex.

4. • Clinically significant disease is more likely
if:
• (1) a grade 3 or 4 hydronephrosis is
present;
• (2) the renal pelvis diameter is > 10 mm;
• (3) the renal pelvis/kidney ratio is > 0.5.

5. Incidence:
• Pre-natal ultrasound
– detects fetal anomaly in 1% of
pregnancies, of which 20-30%
are genitourinary in origin and
50% manifest as hydronephrosis

6. Grading of Severity of
Hydronephrosis
Grade Central Renal Renal
Complex Parenchymal
Thickness
0 Intact Normal
1 Slight splitting Normal
2 Evident splitting Normal
3 Wide splitting Normal
4 Further dilatation Thin

7. Pathophysiology:
• Anatomic and functional processes
interrupts the flow of urine.
• There is a rise in ureteral pressure
causing stretching and dilation; if
pressures continue to rise, leads to
decline in renal blood flow and GFR.
• When significant obstruction is
persistent, it affects nephrogenic tissue
and results in varying degrees of cystic
dysplasia and renal impairment.

9. Proper evaluation protocol

11. I-Mild (Grade II)
• These images shows mild dilatation of the pelvis as well
as the calyces of the right kidney

12. II-Moderate (III)
• The above ultrasound images show cupping of the calyces with moderate dilation
(Right kidney) of the pelvis and calyces. Despite the hydronephrosis the renal
parenchyma is still preserved.

13. III-severe (IV)
• The above sonographic images show marked dilatation of the
pelvicalyces with sever thinning of the renal parenchyma. note
almost total absence of normal renal tissue (cortex).

15. VU reflux

16. PUJ obstruction..early

17. PUJ obstruction ..too late

18. What is this ?

20. Posterior urethral valve