Answers to Case 1-1-10
1. There are no calculi or any renal tract calcifi cation on the control film
(Fig. 1-1-10.1a ). Post-contrast images show complete obstruction with a delayed
nephrogram still evident at 80 min (Fig.1-1-10 1b ) and no drainage past the pelviureteric
junction at 260 min (Fig.1-1-10.1c ). Figure at 80 min (Fig.1-1-10 1b ) and no drainage past the pelviureteric
junction at 260 min (Fig.1-1-10..2 , the MAG-3 activity
curve (graph marked ‘KIDNEY’) shows normal rapid uptake and exponential
clearance in the right kidney. There is normal uptake in the left kidney, but the
curve plateaus rather than decreasing despite administration of Frusemide at
15 min, in keeping with obstruction. Split function is still normal (LK = 49%).
2. The causes are:
• Idiopathic – more common in men and on the left (10% bilateral). Unknown
aetiology, aberrant lower pole vessels are a frequent fi nding, other possible
mechanisms include a persistent urothelial fold or obstruction secondary to
discontinuity in the muscle which disrupts normal peristalsis.
• Calculus – no calcifi cation seen on the control fi lm, but this could be a radiolucent
calculus.
• Tumour (e.g. TCC).
3. In patients with a typical clinical history and imaging fi ndings, no further investigation
is necessary. But in the elderly or those with haematuria, especially in
smokers, ureteroscopy and/or CT may be necessary to exclude a ureteric tumour.
Similarly if a stone is suspected then a CT KUB may be useful.