Cerebroplacental ratio as a prognostic factor for perinatal survival in pregnancies with placental insufficiency

Abstract

During pregnancy, the placenta is the organ responsible for gas exchange and to provide nutritional substrates for the fetus to ensure his development and survival. As the pregnancy progresses with placental dysfunction or insufficiency, as a result of prolonged hypoxemia, several changes occur in fetal circulation, culminating with the brain sparing, characterized by blood flow redistribution with priority to important organs such as brain, heart and adrenals at the expense of spleen, kidney and peripheral circulation. To evaluate this phenomenon, the most commonly used method has been the Doppler, allowing noninvasive evaluation of maternal and fetal circulations. The cerebroplacental ratio (CPR) is obtained by the ratio between the pulsatility index (PI), middle cerebral artery (MCA) and umbilical artery (UA), obtained by Dopplervelocimetry of these vessels, and has been suggested as an important method in prediction of prognosis in high risk pregnancies. The aim of this study is to evaluate the relationship CPR in pregnancies complicated by placental insufficiency and to investigate the role as a prognostic factor for perinatal survival. Methods: We will assess data of pregnant women with placental insufficiency (60 cases) who were admitted to birth at the Hospital das Clínicas da faculdade de Medicina da Universidade de São Paulo (HCFMUSP) from May 2007 to April 2010. We will analyze the clinical data and complementary exams, obtained by analyzing medical records, in addition to an active search through phone contact to obtain data for perinatal survival. The inclusion criteria: gestational age at diagnosis of placental insufficiency between 26 and 34 weeks; diagnosis of placental insufficiency (characterized by increased umbilical artery PI), single pregnancy, live fetus at the beginning of the follow-up of fetal well being; evaluation of CPR until three days before delivery, absence of suspected premature rupture of membranes, absence of fetal anomalies, chromosomal or other abnormalities detected during antepartum or post-natal period; absence of chorioamnionitis at birth or other perinatal infections; birth at the HCFMUSP. The outcome variable is the occurrence of early neonatal death (up to 7d) or late (up to 28d), and infant mortality in the first year of life. We will analyze the association between results of fetal assessment tests performed before birth (cardiotocography, fetal biophysical profile, Dopplervelocimetry of fetal circulation, placental and cerebroplacental ratio) with the occurrence of neonatal death or until the first year.