Randomized Clinical Trial Of Doppler Indices For Improving Obstetrical Outcome

Abstract

The ultimate goal of antepartum fetal surveillance is to prevent fetal death and improve perinatal morbidity. The Current standard antepartum tests are the non stress test, the contraction stress test and the biophysical profile. In this study, the efficacy of umbilical Doppler velocimetry and nonstress testing in improving perinatal outcome in a high risk pregnant population were compared. A reactive nonstress test depends on an adequate integrated neuromuscular system while Doppler vel<-.::imetry detects any change in the blood flow impedance in different fetal vessels. Both tests are known to be affected in compromised pregnancies.

During a normal pregnancy, vascular adaptive changes occuring in the maternal placental bed vessels are necessary to enable them to deliver 500 ml of blood/minute into the intervillous space (Brosens et al., 1967). The cytotrophoblast invades the media of the spiral arterioles, a process completed sometime between the 14th and the 20th week gestation, resulting in the convertion of the muscular spiral arteries into thin-walled, flaccid uteroplacental vessels which progressively dilate and loose their vasomotor tone. This is vital for adequate placentation and a normal uteroplacental blood flow (Robertson et a! 1975).

In preeclampsia and pregnanc1es complicated by I.U.G.R., this process of trophoblastic invasion does not occur, and consequently, the maternal blood flow to the placenta is less than normal (Robertson et a! 1975 and 1981).