Urogenital ImagingAgenesis, renal
absence of the kidney. True
renal agenesis is defined as the complete
congenital absence of
renal tissue, in contrast to acquired absence of
renal tissue due to atrophy. Atrophy of sufficient degree to mimic agenesis may occur in conditions such as multicystic dysplastic kidney and ureteropelvic junction
obstruction. True agenesis may be the result of failure of formation of the ureteric bud (in which case
cystoscopy will reveal a hemitrigone) or due to maldevelopment of the metanephric blastema (in which case partial development of the
ureter may be present).
Renal agenesis occurs in 1 in 1000 to 5000 births. The male : female ratio is 1.8:1. The condition is slightly commoner on the left side. A familial tendency has been noted.
The diagnosis may be suggested on plain radiographs, when the renal outline is absent and the colon is seen to occupy the renal fossa on the affected side. However, the condition is usually detected as an incidental finding on ultrasound, when no kidney can be demonstrated on one side. Intravenous urography, CT (Fig.1), MRI, or renal scintigraphy can be used to confirm ipsilateral absence of renal tissue, and exclude the presence of an ectopic kidney. Significant anomalies of the contralateral kidney are rare. The ipsilateral adrenal gland is absent in less than 10% of cases. Conversely, genital anomalies are frequently associated, most commonly absence of the ipsilateral seminal vesicle in males, and unicornuate uterus or bicornuate uterus with a rudimentary ipsilateral horn in females. These latter findings are best evaluated with MRI. Bilateral renal agenesis is extremely rare and incompatible with life. About 75% of patients are male. The characteristic findings of Potter's syndrome are present.
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Axial contrast-enhanced CT section showing agenesis of the left kidney.
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Agenesis, renal, Fig.1 | |