Renal Artery Duplex Examinations in Neonates

Introduction.—Hypertension in neonates, although uncommon, may be the result of congenital renal artery stenosis, or, more frequently, coarctation of the aorta. Renal artery duplex examinations have been used in our institution to evaluate neonates. The purpose of this study was to evaluate the efficacy of duplex ultrasound in the evaluation of renal arteries and kidneys in neonates.

Methods.—Eleven infants from January 2006 through January 2009 were studied with the use of color duplex ultrasound. Seven examinations were performed for hypertension, one for renal failure, one with increased creatinine, one for suspicion of renal vein thrombosis, and one for hematuria. Protocols were modified during this 3-year period and now consist of examining the kidneys, renal artery, and vein and aorta from both flanks with the use of a 9–3 MHz transducer.

Results.—By the use of standard renal artery protocols, 8 neonates were found to be healthy, with the exception that all subjects had greater-than-expected aortic velocities. Two subjects (identical twins) had abnormal signals in the aorta and renal arteries consistent with proximal aortic obstruction. One infant in renal failure had high resistance signals in both kidneys consistent with renal parenchymal disease. Kidney size varied with infant weight and ranged from 2 to 4 cm. Symmetrical measurements were interpreted as normal.

Conclusion.—This study demonstrates that duplex examinations in neonates is feasible and that minor adjustments in standard protocol and interpretation criteria allow for adequate assessment to evaluate for vascular causes of hypertension.