Abdominal Ultrasound Registry Practice Test

The correct choice is the horseshoe kidney, which is a condition where the lower poles of both kidneys are fused together across the midline of the body, typically forming a U-shaped structure. This anatomical anomaly occurs during fetal development when the kidneys are forming and is characterized by the fusion of the renal tissue at the lower aspect.

The horseshoe kidney can lead to a variety of clinical implications, including obstruction of the urinary tract due to the altered position of the kidneys and a higher propensity for kidney stones or infections. The unusual position and shape can also be associated with other anatomical anomalies.

In contrast, renal dysplasia refers to an abnormal development of the kidney that often results in reduced function or non-functioning kidneys but does not involve fusion across the midline. Crossed fused ectopic kidney is a separate anomaly where one kidney is located on the opposite side of the midline and fused with the kidney in its normal position but does not typically connect the lower poles. A pelvic kidney is a condition where the kidney is located in the pelvis instead of the abdomen; it does not involve fusion across the midline either.

Overall, the defining feature of horseshoe kidney is its characteristic U shape formed by the fusion of the lower poles of the kidneys at