Presentation
Abdominal fullness, dull aching pain, tender on palpation.
Patient Data
Both kidneys are fused across midline in horseshoe configuration, forming renal isthmus at L2-L4 vertebral level.
Right kidney is composed of three distinct calyceal systems demarcated by well-defined cortical bands in between, making a triplex configuration. Isthmus of the horsheshoe configuration is made fully by the third moiety of the right kidney.
Left kidney is duplex in configuration.
All moieties of both kidneys, including the isthmus (third moiety of right kidney) show prompt and symmetric uptake of IV contrast. However, excretion is very slow in both moieties of left kidney.
Cortical thickness and corticomedullary differentiation are well-defined in all three moieties of the right kidney, with mild dilatation of calyces and pelves.
Left kidney shows severe cortical thinning in both moieties, with gross pelvicalyceal dilatation, clubbing of fornices and abrupt narrowing at pelviureteric junction (PUJ).
All three moieties of right kidney unite into a single ureter, which appears prominent (6 mm).
Left side has two ureters that are not dilated.
No radiodense stone is seen in either kidney or ureter.
Abdominal aorta is bifurcated at L2 level. IVC is bifurcated at L4 level as normal.
Both kidneys are fused across midline in horseshoe configuration, forming renal isthmus at L2-L4 vertebral level. Right kidney is triplex in configuration, with well-defined cortical bands in between. Left kidney is duplex.
Left kidney shows severe cortical thinning in both moieties, with gross pelvicalyceal dilatation, clubbing of fornices and abrupt narrowing at pelviureteric junction (PUJ).
Case Discussion
While horseshoe configuration and PUJ obstruction are not uncommon findings, triplex kidney is an extremely rare entity 1, and seldom occurs alone 1,2. Our patient is type-III based on Smith's classification of triplex kidneys 2, having all three ureters united and draining into a single vesical orifice. The importance of reporting the triplex configuration is to beware that an undetected or residual third moiety may turn out to be a source of persistent symptoms, or an unfortunate indication for repeated surgery 1.
We note that while the MRI shows most of the findings, it is the CT that shows all of them and in detail, reminding that CT urogram is the gold standard of urinary tract imaging 3.
We also note that the left-sided PUJ obstruction producing severe hydronephrosis has remained silent and undetected hitherto, highlighting the silent-killer nature of PUJ obstructions 3.
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