Pelvi-ureteric junction obstruction

Pelvi-ureteric junction (PUJ) obstruction/stenosis, also known as ureteropelvic junction (UPJ) obstruction/stenosis, can be one of the causes of an obstructive uropathy. It can be congenital or acquired with a congenital PUJ obstruction being one of the commonest causes of antenatal hydronephrosis.

It may present in both paediatric and adult populations although they tend to have differing aetiology. The estimated incidence in paediatric populations is ~1 per 1000-2000 newborns, and there is a male predominance (M:F = 2:1).

Many cases are asymptomatic and identified incidentally when the renal tract is imaged for other reasons. When symptomatic, symptoms include recurrent urinary tract infections, stone formation and even a palpable flank mass. They are also at high risk of renal injury even by minor trauma.

Classically intermittent pain after drinking large volumes of fluid or fluids with a diuretic effect is described, due to the reduced outflow from the renal pelvis into the ureter 8.

PUJ obstruction is most commonly unilateral but is reported to be bilateral in ~30% (range 10-49%) of cases 10. There is a recognised predilection towards the left side (~67% of cases).

During embryogenesis, the pelvi-ureteric junction forms usually around the fifth week and the initial tubular lumen of the ureteric bud become recanalised by ~10-12 weeks. The PUJ area is the last to recanalize. Inadequate canalization is thought to be the main embryological explanation of a PUJ obstruction. Extrinsic obstructions secondary to bands, kinks, and aberrant vessels also are commonly encountered.

Aetiology
  • congenital (neonatal)
    • idiopathic and often unknown; proposed causes include
      • abnormal muscle arrangement at the PUJ
      • anomalous collagen collar at PUJ
      • ischaemic insult to PUJ region
      • urothelial ureteral fold
    • extrinsic ureter compression or encasement
      • crossing vessel (at PUJ)
  • adult
    • preceding renal pelvic trauma
    • obstructing calculus immediately distal to PUJ
    • previous pyelitis with scarring
    • intrinsic malignancy, e.g. upper tract urothelial carcinoma
    • extrinsic ureter compression or encasement
      • fibrosis
      • crossing vessel (at PUJ)
      • malignancy
Associations
Fluoroscopy/IVU

Traditionally intravenous urography/pyelography (IVU/P) has been performed for assessing for PUJ obstruction. The administration of Furosemide/Lasix may be used to assist confirming the diagnosis, in particular, to exclude a dilated non-obstructed upper collecting system (so-called 'baggy pelvis').

Ultrasound
  • will often show a dilated renal pelvis with a collapsed proximal ureter
  • Doppler sonography: the obstructed kidneys may show higher resistive indices
CT

May show evidence of hydronephrosis +/- caliectasis with collapsed ureters. Useful for assessing crossing vessels at the PUJ, especially when surgical intervention is planned 5,7.

Renal scintigraphy

Renal scintigraphy can quantitate the degree of obstruction:

  1. 99mTc MAG3: Agent of choice due to a high extraction rate, which may be necessary for an obstructed system. Diuretic (Furosemide) renogram is performed to evaluate between obstructive vs. nonobstructive hydronephrosis. The non-obstructive hydronephrosis will demonstrate excretion (downward slope on renogram) after administration of diuretic from the collecting system. Whereas mechanical obstructive hydronephrosis will show no downward slope on renogram, with retained tracer in collecting system
  2. 99mTc DTPA: Not the agent of choice because of 99mTc-DTPA predominantly glomerular filtration. Glomerular function declines earlier and more rapidly than does tubular function in obstructive uropathy. 99mTc-DTPA may be used if the kidney is known to have a good renal function.

Treatment depends on the underlying cause. In a majority of congenital cases, the condition is essentially benign, and usually, no intervention is required. However, when there is a definitive structural obstruction (commonly adult cases), surgical intervention with pyeloplasty or stenting may be necessary.

General imaging differential considerations include:

Share article

Article information

rID: 9714
Section: Pathology
Synonyms or Alternate Spellings:
  • PUJ obstruction
  • UPJ obstruction
  • Renal pelvic dilatation
  • Ureteropelvic junction obstruction (UPJO)
  • UPJO
  • Ureteropelvic junction (UPJ) obstruction
  • Pelviureteric junction obstruction
  • PUJ stenosis
  • UPJ stenosis
  • Ureteropelvic junction stenosis
  • Pelviureteric junction stenosis

Support Radiopaedia and see fewer ads

Cases and figures

  • Drag
    Figure 1: hydronephrosis due to PUJ obstruction
    Drag here to reorder.
  • Drag
    PUJ Obtruction
    Case 1: hydrographic MR urogram
    Drag here to reorder.
  • Drag
    PUJ Obtruction
    Case 1: 3D
    Drag here to reorder.
  • Drag
    Right PUJ obstruc...
    Case 2: ultrasound
    Drag here to reorder.
  • Drag
    Renogram activity...
    Case 2: scintigraphy
    Drag here to reorder.
  • Drag
    Case 3: from accessory renal artery
    Drag here to reorder.
  • Drag
    PUJ obstruction
    Case 4
    Drag here to reorder.
  • Drag
    PUJ obstruction
    Case 4
    Drag here to reorder.
  • Drag
    PUJ obstruction
    Case 5: with calculus
    Drag here to reorder.
  • Drag
    Case 6
    Drag here to reorder.
  • Drag
    Case 7
    Drag here to reorder.
  • Drag
    Left hydronephros...
    Case 8: extrinsic ureter compression by fibrosis
    Drag here to reorder.
  • Drag
    Mru2
    Case 9: post-pyeloplasty
    Drag here to reorder.
  • Drag
    Excretory MR urogram
    Case 10: excretory MR urogram
    Drag here to reorder.
  • Drag
    Case 11: involving lower pole moiety of duplex kidney
    Drag here to reorder.
  • Drag
    Case 12
    Drag here to reorder.
  • Drag
    Case 13: with contralateral bifid ureter
    Drag here to reorder.
  • Drag
    Case 14: with extrarenal pelvis
    Drag here to reorder.
  • Drag
    Case 15
    Drag here to reorder.
  • Drag
    Case 16: chronic PUJ obstruction
    Drag here to reorder.
  • Updating… Please wait.
    Loadinganimation

    Alert accept

    Error Unable to process the form. Check for errors and try again.

    Alert accept Thank you for updating your details.