Pelviureteric obstruction - high-grade

Case contributed by Sally Ayesa

Presentation

Abnormal left kidney on antenatal ultrasound.

Patient Data

Age: 4 months

Dynamic Renal Scintigraphy (99m-Tc MAG3) with diuretic

Nuclear medicine

Dynamic images were acquired for 22 minutes post injection of tracer, with concurrent administration of lasix. Additional planar images have been acquired post void, as well as following a 90 minute delay. 

There is mild delay in perfusion to the left kidney, with reduced uptake of tracer by the left kidney compared to the right. Excretion of tracer by the left kidney is mildly delayed, demonstrated by 12 minutes. There is progressive accumulation of radiourine in the left collecting system over the course of the study, with no significant clearing demonstrated on post void or delayed phase images. 93% of counts remain in the left kidney on the 1.5 hour delayed image (compared to the post void image). A clearance time cannot be calculated as the renogram curve is upgoing.

Scan appearances of the right kidney are near normal, with prompt perfusion, normal extraction and satisfactory excretion of tracer. The lasix half clearance time of the right kidney is mildly prolonged (20 minutes) however normal clearance is observed on review of the images. 

The left:right differential function is calculated at 37%:63%.

Case Discussion

Imaging features are consistent with a high grade left PUJ obstruction. Over the course of the dynamic phase of the study, there is progressive accumulation of radiourine within the renal pelvis, with drainage not assisted by voiding, gravity or time. Over time, high grade PUJ obstruction can lead to a decrease in renal function, as seen in this case. 

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