Pelviureteric Junction Obstruction

Epidemiology

• Occurs in both children and adults
• Incidence: 1 in 1000–2000 newborns
• Male to female ratio: 2:1

Pathophysiology

• Most often unilateral; bilateral in ~30%
• Left-sided predominance (~70%)
• During embryogenesis, the pelviureteric junction forms around the fifth week and the initial tubular lumen of the ureteric bud becomes recanalised by around 10-12 weeks. The PUJ area is the last region to recanalise. Inadequate canalisation is thought to be the main embryological explanation of a PUJ obstruction.
• Extrinsic obstructions secondary to bands, kinks, and aberrant vessels also are commonly seen.

Causes

Congenital (Neonates)

Intrinsic:

• Functional: absent/abnormal peristalsis
• Anatomical: narrowed/kinked PUJ, mucosal folds

Extrinsic:

• Aberrant renal vessels compressing the ureter

Associated anomalies:

• Renal duplication, multicystic dysplastic kidney, horseshoe kidney

Acquired (Adults)

Intrinsic:

• Trauma-induced scarring, distal calculi, pyelitis, malignancy

Extrinsic:

• Fibrosis, abdominal aortic aneurysm, malignancy

Complications

• Urinary tract infection
• Progressive renal impairment
• Renal pelvis rupture → uroma

Clinical Features

• Often asymptomatic; detected via imaging
• In adults:
  • UTI (due to obstruction)
  • Loin pain (post-fluid intake)
  • Worsening renal function

Investigations

Blood Tests

• FBE
• CRP
• U&Es, glucose

Imaging

Ultrasound:

• Dilated renal pelvis, collapsed ureter
• Doppler: Resistive index >0.7

CT with contrast:

• Demonstrates hydronephrosis, ureter collapse, renal thinning
• Detects crossing vessels

Renal Scintigraphy (Gold Standard):

• 99mTc-MAG3 preferred
• Diuretic renogram differentiates obstructive vs non-obstructive hydronephrosis
• 99mTc-DTPA for patients with good renal function

MRI Urography:

• No radiation; detailed anatomy and function
• Ideal for children

Management

• Observation for benign congenital cases

Surgical:

• Pyeloplasty (open or laparoscopic)
• Stenting
• Nephrostomy (for acute decompression in sepsis)

Disposition

All patients should be referred to Urology for specialist review and ongoing management

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References

FOAMed

• Cadogan M. Dietl’s Crisis. LITFL
• Hartung MP. Abdominal CT: GU imaging. LITFL
• Beech G. CT Case 067 LITFL

Publications

• Borin JF. Ureteropelvic Junction Obstruction in Adults. Rev Urol. 2017;19(4):261-264.
• Ureteropelvic Junction Obstruction. Stat Pearls