Diagnosis of aortic coarctation by tardus-parvus renal artery Doppler signal in an infant with multicystic dysplastic kidney: a case report.

We report an infant with known unilateral multicystic dysplastic kidney (MCDK) who underwent renal ultrasonography and Doppler spectral waveform analysis for investigation of hypertension. A tardus-parvus waveform was demonstrated in the renal artery on the normal side suggesting either renal artery or more proximal stenosis. Coarctation of the aorta was subsequently demonstrated.