The Relationship of Early Diastolic Notch in Uterine Artery Doppler Velocimetry and the Renal Function of Patients with Pregnancy Induced Hypertension

Choi, E K; Choi, H M; Lee, Y H; Yoo, Y K; Cho, J S; Park, Y W; Kim, J U

Abstract

The pregnancy induced hypertension is a grave complication of mid or late pregnancy but its cause and pathophysiology remain unclear. Multiorgan dysfunction can occur but the kidney is one of the most vulnerable organs and the renal functional deteriorations are due to a decrease of the renal blood flow and glomerular filtration rate caused by intrarenal vasospasm. Recently the development of Doppler velocimetry of uterine artery in mid and third trimester of pregnancy, the obstetrician can expect pregnancy induced hypertension by abnormal Doppler study. Among the many parameters, the early diastolic notch in uterine artery is stressed because its sensitivity and positive predictive value are higher compared to resistance index or pulsatility index. It is the typical waveform in uterine artery Doppler velocimetry due to high vascular resistance and its consistency after midtrimester is related with ischemic changes of placenta, pregnancy induced hypertension and poor perinatal prognosis. We hypothesize if a patient with pregnancy induced hypertension shows low notch index (NI: early diastolic minimal flow velocity (A)/diastolic maximal flow velocity (B)) in uterine artery Doppler velocimetry, the degree of systemic endothelial damage and increase of vascular resistance are more severe than that of a patient shows no notch and more profound influences take on renal function. This study is designed to evaluate the relationship of NI and maternal renal function of patients with pregnancy induced hypertension by NI. From January 1994 to December 1996, we studied 156 pregnant women showing early diastolic notch in uterine artery beyond the 28th weeks of gestation and delivered her baby within 4 weeks from the uterine artery Doppler velocimetry. We looked into the maternal random urine protein, proteinuria for 24 hours, maternal serum blood urea nitrogen (BUN) and creatinine, maternal blood pressure, creatinine clearance, got and compared the mean NI of each parameters. We suggest that the NI is highly related with not only occurrence of pregnancy induced hypertension or poor perinatal outcome, but also maternal renal function such as the grade of proteinuria or creatinine clearance in the patients with preeclampsia and we should be alert to maternal renal function in patients with early diastolic notch in uterine artery Doppler velocimetry.