Validation of noninvasive fetal renal artery flow measurement by pulsed Doppler in the lamb.

Abstract

Our objective was to evaluate the accuracy of quantitative measurement of blood flow of the left renal artery in the fetal lamb by means of range-gated, two-dimensional pulsed Doppler ultrasonography. Doppler measurements were compared with invasive measurements obtained with a perivascular flow probe (Transonic) placed on the fetal renal artery. Renal blood flow was manipulated acutely either by volume expansion or depletion or by means of pharmacologic agents. With each manipulation values of the left fetal renal artery blood flow were obtained with both methods. The size of the fetal renal artery was determined by postmortem examination. A total of 36 paired flow measurements were obtained on five fetuses. One fetus had only Transonic determination of renal blood flow. Pulsed Doppler ultrasonography blood flow and transit-time ultrasonography blood flow estimations were correlated (F = 82.4, R2 = 0.73, p < 0.001). This study suggests that two-dimensional pulsed Doppler can reliably estimate renal blood flow in the fetal lamb.