Renal Doppler as a Diagnostic Clue to Post-ductal Coarctation of the Aorta in an Adolescent Male: A Case Report.

Renal Doppler ultrasonography is a widely used, non-invasive modality in the evaluation of secondary hypertension, particularly in detecting renovascular causes such as renal artery stenosis. It was chosen as the initial modality in this case due to its non-invasive nature, absence of radiation, and established role in young patients with suspected secondary hypertension. However, it may also reveal indirect hemodynamic signs of proximal aortic obstruction. We report a rare case of a 15-year-old male who presented with unexplained systolic and diastolic hypertension and was subsequently diagnosed with post-ductal coarctation of the aorta, initially suspected based on bilateral tardus-parvus waveforms, an uncommon and often overlooked finding on renal Doppler. Further evaluation with CT aortography confirmed a post-ductal narrowing just distal to the left subclavian artery, with well-developed collateral circulation. Rather than being a novel function, the presence of bilateral parvus-tardus patterns illustrates the clinically valuable indirect role of renal Doppler in raising suspicion of upstream aortic obstruction. This case highlights the importance of considering coarctation in the routine workup of hypertensive adolescents and underscores the role of renal Doppler as an indirect but valuable diagnostic clue in extra-renal vascular abnormalities.