Objective: The elevation in blood pressure associated with preeclampsia appears to be associated with a shift in the renal pressure natriuresis curve. Pressure natriuresis is modulated by renal medullary pressure. In obstructive uropathy, Doppler sonography has been used to indicate changes in renal venous impedance, possibly measuring alterations in medullary pressure and compliance in this condition. The hypothesis tested in this study was that an elevation in renal venous pulsation may occur in preeclampsia compared with normal pregnancy.
Methods: Seven patients with clinical evidence of preeclampsia were referred for fetal well-being confirmation by sonography in the third trimester. Seven pregnant patients without renal disease or hypertension reviewed in the third trimester served as a control group. Doppler studies of the interlobar arteries and veins of both kidneys were performed, with a total of 14 kidneys imaged per group. Arterial and venous impedance indices were obtained. The impedance indices for the patients were compared by the Student t test.
Results: No significant difference was noted between the arterial resistive indices. The mean venous impedance index for the hypertensive patients was 0.50 +/- 0.12, and that for the control patients was 0.37 +/- 0.06 (P = .003).
Conclusions: Preeclampsia in the third trimester appears to be associated with altered medullary venous pulsation, possibly indicating reduced medullary pressure.