Paediatric Renal pathology

Pelvic-Ureteric Junction (PUJ) Obstuction

  • Also called a uretro-pelvic junction (UPJ) obstruction.
  • May be developmental or acquired (generally a post-operative complication).
  • In an infant, it is usually a congenital, developmental stricture of the origin of the ureter at the renal pelvis.

Causes include:

  • Abnormal position of insertion of ureter to renal pelvis.
  • Anomalous vessel overlying/compressing the proximal ureter.
  • Ectopic or malrotated kidney.
  • Ureteral hypoplasia.

Diagram of a PUJ obstruction.

Note the normal, non dilated ureter.

Ultrasound of a neonate with a PUJ obstrucion.  There is preservation of the cortical thickness and no hydroureter.

Ultrasound image- Transverse view of a normal neonatal kidney.

Ultrasound of a neonate with a PUJ obstrucion. There is preservation of the cortical thickness and no hydroureter.

Vesico-Ureteric Reflux (VUR or urinary reflux)

VERY IMPORTANTLY: Ultrasound cannot exclude VUR. ie it is a poor negative predictor.

VUR is incompetence of the ‘valve’ like insertion of the ureter into the bladder, allowing urine to reflux back up from the bladder, particularly during micturition.

The ureter actually passes through a ‘mucosal-tunnel’ in the bladder wall. Bladder filling

Grading:

  • Grade I – Reflux into nondilated ureter
  • Grade II – Reflux into renal pelvis and calyces without dilation
  • Grade III – Reflux with mild to moderate dilation and minimal blunting of fornices
  • Grade IV – Reflux with moderate ureteral tortuosity and dilation of pelvis and calyces
  • Grade V – Reflux with gross dilation of ureter, pelvis, and calyces, loss of papillary impressions, and ureteral tortuosity.
    REF: The International Reflux Study in Children. J Urol. Nov 1992

Presentations:

The primary 2 presentations are:

  1. Pyelectasis or hydronephrisis/hydroureter seen on antenatal ultrasound
  2. Urinary tract infection.
    Investigations:

There is differing opinion on the best primary investigation for neonates/infants.

  1. Ultrasound
  2. DMSA – dimercaptosuccinic acid
  3. MCU – Micturating Cysto-urethrogram
  4. Radionucleid cystography

Ultrasound image- Right sided VUR.

Use of color doppler to demonstrate retrograde flow through the vesic-ureteric junction (VUJ).

Colour doppler is used to show retrograde flow (blue) back into the ureter following the normal ureteric jet (red).

Ultrasound image- Left sided Urinary reflux

Dilated ureter at the VUJ with reflux shown using colour doppler.

Duplication Anomoly

An 8 year old girl presented with a recent UTI.

Duplex anomaly on the right side with an obstructed atrophied upper pole moeity with its ureter ectopically inserting into the bladder base and obstructed by a small ureterocoele.

ltrasound image- There is an obstructive atrophied upper pole system.

Ultrasound image- The lower pole system shows mild to moderate hydronephrosis and minimal cortical thinning that may be accentuated by the hydronephrosis.

Ultrasound image- The lower pole ureter is more dilated i.e. has features of a mild megaureter 14mm in width.

Ultrasound image- There are findings on the right side consistent with a duplication anomaly with an obstructed atrophied upper pole moeity due to a ureterocoele lying ectopically at the bladder base just above the internal urethra.

Ultrasound image- Refluxing/partly obstructed lower pole system on the right side with a ureterocoele at its insertion site into the bladder base and a dilated ureter and collecting system.

Ultrasound image- Right and left ureteric jets.

Ultrasound image- The lower pole moiety /2nd ureter is also partly obstructed/refluxing due to a ureterocoele at its insertion site .

Ultrasound image- Dilated right sided ureters.