Maternal renal interlobar vein impedance index is higher in early- than in late-onset preeclampsia

Abstract

Aims: To compare Renal Interlobar Vein (RIV) Doppler parameters during uncomplicated pregnancy (UP), early onset (EPE) and late onset preeclampsia (LPE), and to evaluate postnatal persistence of gestational abnormalities. Methods: All women had a renal duplex scan according to a standard protocol. Women with UP were evaluated at 28 to 32w and at 34 to 37 weeks, those with preeclampsia were evaluated once during pregnancy, and all women were rescanned between 4 w and 18 months after delivery. During the scan, 3 consecutive measurements of RIV maximum (MxV) and minimum (MnV) velocities per kidney were printed ; afterwards, the mean of these 3 values was recorded, and Delta velocity (DeltaV) and Impedance Index (RIVI) were calculated respectively as MxV-MnV and DeltaV/MxV. Preeclampsia at gestation < 34 weeks was defined EPE, and at gestation „d 34 weeks was defined LPE. For UP, EPE and LPE, gestational and non-gestational values were categorised. Group- specific means „b SD were calculated and compared with T- and F-test. Results: A total of 18 women with UP, 21 with EPE and 19 with LPE were evaluated. For both left and right kidney, RIVI was significantly higher in EPE than in LPE (0.48„b0.11 versus 0.41„b0.07, p=0.02, resp. 0.46„b0.15 versus 0.36„b0.11, p=0.02), and also higher than in UP (0.48„b0.11 versus 0.36„b0.04, p = 0.0001 resp. 0.46„b0.15 versus 0.33„b0.04, p = 0.001). For LPE, the differences with UP were not or borderline significant. None of the gestational differences persisted after delivery. Conclusion: RIV Impedance Index is significantly higher in EPE than in LPE and UP. This observation is consistent with other reports, showing evidence for high systemic vascular resistance in EPE, but not in LPE. RIV Doppler studies are not useful to evaluate persistence of hemodynamic abnormalities after preeclampsia.