Pelvi-ureteric junction obstruction
Key points
Antenatal hydronephrosis
Society for Foetal Urology (SFU) grading of antenatal hydronephrosis
Grade
0 - Normal
1 - Dilatation of renal pelvis - usually resolves in 3rd trimester - no need for MCUG in most circumstances
2 - Pelvis + major calyces
3 - Pelvis + major + minor calyces
4 - Grade 3 + cortical thinning
Normal = <10mm at 32/40
Normal for child is 7mm
HK Dhillon 1998 GOSH antenatal hydronephrosis experience:
12mm AP diameter: Not likely to need operation
12-50mm: Moderate risk
>50mm: Surgery likely
Causes of PUJ obstruction (PUJO)
Intrinsic obstruction – most common
‘Adynamic’ segment
Crossing vessels – 30%
Rare causes: fibroepithelial polyps and fungal balls
Horseshoe kidney – most common complication is PUJO due to ureter compression over isthmus
Retrocaval ureter
Tortuous, kinked dilated ureter
MAG3 - O'Reilly classification
1: Normal uptake with quick washout – normal
2: No washout with diuretic – obstructed
3a: Normal uptake, falls rapidly with diuretic – dilated, non-obstructed – no action needed
3b: Slow drainage with diuretic – do DMSA and perform pyeloplasty if function is affected
4: Second peak – Homsy’s sign associated with obstruction secondary to high urine flow
Management
Mild to moderate hydronephrosis - can monitor with 6 monthly USS as most will resolve
Give antibiotics for first year of life - trimethoprim 2mg/kg OD
Severe should have MAG3, if obstructing and if affected kidney renal function below 40-35% - operate
If symptomatic - operate
Less than 10% function consider nephrectomy
Can have both PUJO and VUJO - do retrograde and stent at time of pyeloplasty
Anderson Hynes Pyeloplasty success rate >95%
Bilateral PUJO
Operate on good side first to ensure safety
Only operate on one side, as post op complications such as sepsis, clot or obstruction can lead to renal failure if bilateral
Ureterocalycostomy
For recurrent PUJ and short ureter
PUJ in duplex systems
Always affects lower pole - should do fish mouth anastomosis to minimise blockage of upper pole
Standard scenario
Concerns:
1. Renal function
2. Sepsis
3. Pain
Ensure that patient is resuscitated, pain managed and sepsis treated
Review antenatal scans
AP diameter - can quote GOSH paper
Cortex thickness, cysts
Other features - liquor volume etc
History:
Review of all previous imaging and management
Episodes of pain after drinking
UTIs
Examination:
Palpable renal pelvis in infants
Investigations:
USS
MAG3 with diuretic
If nephrostomy in - antegrade pyelogram and DMSA
Management:
If <40%-35% function in affected kidney - Anderson-Hynes Pyeloplasty + JJ stent
Open retroperitoneal approach in age <2
Laparoscopic transperitoneal age >2
Other techniques:
Retroperitoneoscopic
Vascular hitch for crossing vessels
Y-V pyeloplasty
Scardino-prince (vertical flap)
Culp de Weerd (spiral flap)
For short ureter or complex redo - ureterocalycostomy - transect lower pole and anastomose to lower calyx
+/- mobilise kidney
Pyeloplasty follow up
USS in 3 months
If resolving dilatation, 6 month then yearly USS
MAG3 only if no improvement (or worsening) in dilatation
References
Fernbach SK, Maizels M, Conway JJ. Ultrasound grading of hydronephrosis: introduction to the system used by the Society for Fetal Urology. Pediatr Radiol. 1994;23 (6): 478-80
Essentials of Pediatric Urology, 3rd edition, 2022, Chapter 7 Upper Tract Obstruction
Dhillon HK. Prenatally diagnosed hydronephrosis: the Great Ormond Street experience. Br J Urol. 1998 Apr;81 Suppl 2:39-44. doi: 10.1046/j.1464-410x.1998.0810s2039.x. PMID: 9602794.