ABSTRACT
Bilateral renal agenesis is usually a diagnosis of exclusion, with the presentation being that of severe oligohydramnios or anhydramnios in the second trimester. The renal fossae are hard to image due to the lack of liquor. Additionally, the suprarenal glands occupy the renal fossae when the kidneys are not formed. These can mimic normal renal tissue on scan, thus making the diagnosis complicated. The lack of a normally filled bladder and renal arteries in the setting of anhydramnios would be features in favor of bilateral renal agenesis. Absence of renal tissue in the normal site, namely the renal fossa, may be due to true agenesis or due to ectopic presentation of the kidney. This could be either in the fetal pelvis or due to a fusion with the contralateral kidney. In either case, the kidney could show signs of pelvicalyceal dilatation due to the abnormal position and contour of the drainage system.
