Sonographic Anatomy and Normal Measurements of the Human Kidneys: A Comprehensive Review.

Ultrasound is the primary, non-invasive imaging modality for evaluating renal anatomy and function in both acute and chronic settings. Familiarity with normal kidney morphology, cortical and parenchymal thickness, echogenicity, and Doppler parameters is essential for differentiating normal findings from early manifestations of disease. This review summarizes established reference ranges and anatomical variants from the 1950s to 2025, highlighting differences related to age, sex, body habitus, and ethnicity. Practical emphasis is placed on the interpretation of renal size, cortical thickness, echogenicity, and resistive indices in clinical scenarios such as chronic kidney disease, renovascular hypertension, acute obstruction, and renal transplantation. By integrating sonographic measurements with clinical and laboratory findings, clinicians can achieve timely diagnosis, monitor disease progression, and guide therapeutic decisions while minimizing the need for invasive or radiation-based imaging.