Horseshoe kidney: the kidneys are fused at the lower pole and placed close the midline. The anomaly itself is generally inconsequential. Also common in trisomy 18 and Turner syndrome.
Ectopic kidney: the kidney is not in the normal position, commonly located in the small pelvis. Ectopic kidney can be mistaken for renal agenesis at sonographic examination.
Horseshoe kidney (ren arcuatus) at trisomy 18, 26-week fetus: Ren arcuatus, Macro, autopsy (72083)