Absence of Kidneys

Renal agenesis is defined as the complete absence of both kidneys and ureters. As a result, the fetus cannot produce urine. The main ultrasound feature of this condition is the impossibility to visualize both kidneys and bladder, and it is associated with severe oligohydramnios after the 16th week of gestation.

Unilateral renal agenesis (URA) is the complete absence of one kidney and ipsilateral ureter. This condition occurs 1-2:1000 births, and frequently goes unrecognized even though it is detectable by ultrasound. In fact, in contrast to bilateral renal agenesis, in URA, no indirect signs are associated.

Renal ectopy (from the Greek word “ectopia” meaning “wrong position”) is defined by a kidney malposition due to early embryologic failure of the kidney to ascend to the retroperitoneal renal fossa.