Which finding is expected in the contralateral kidney given the pathology depicted in this image?

The ultrasound image shows a sagittal view of the right kidney with multiple anechoic (black), non-communicating cysts of varying sizes distributed throughout the renal parenchyma, consistent with autosomal dominant polycystic kidney disease (ADPKD).

ADPKD is a hereditary disorder characterized by the progressive development of multiple bilateral renal cysts, which leads to renal enlargement and eventual loss of function. This condition typically affects both kidneys, making bilateral polycystic involvement expected. Therefore, the same cystic appearance is anticipated in the contralateral (left) kidney as well.

Comparison of answer choices:

A. Duplicated collecting system: This is a congenital anomaly but does not result in diffusely cystic kidneys.

B. Polycystic kidney: Correct. Bilateral renal involvement is the hallmark of ADPKD.

C. Parapelvic cysts: These are simple cysts located in the renal sinus and do not exhibit the diffuse pattern seen here.

D. Atrophic kidney: Not typical in the contralateral side in ADPKD; the disease affects both kidneys symmetrically.