Pelvic kidney. There are quite a few developmental anomalies of the kidneys that we can potentially pick up on cross-sectional imaging. This is one of the less common ones – failure of ascent of one of the kidneys, the left (LK) in this example. These can potentially cause some diagnostic confusion, for example if the patient develops an obstructing calculus their symptoms will be localized to the pelvis instead of the flank. Also, they can be mistaken for a pelvic mass on clinical examination. Other renal anomalies include duplex collecting systems, horseshoe kidney, and unilateral agenesis.