OBGYN -- Unit 2: Obstetrics - B. Abnormal Obstetrics

Terms in this set (180)

A. When a pregnancy is complicated by fetal growth restriction, various fetal physiologic parameters require assessment. In growth-restricted pregnancies, oligohydramnios is frequently found. This finding is presumably due to reduced fetal blood volume, renal blood flow and urinary output. Chronic hypoxia is responsible for diverting blood flow from the kidney to organs that are more critical during fetal life. The significance of the amniotic fluid volume with respect to fetal outcome has been well documented. Ninety percent of patients with oligohydramnios delivered growth restricted infants. These infants experienced a high rate of fetal compromise. The systolic/diastolic (S/D) ratio of the umbilical artery is determined by Doppler ultrasound. An increase in the S/D ratio reflects increased vascular resistance. It is a common finding in IUGR fetuses. A normal S/D ratio indicates fetal well-being. As vascular resistance increases, the S/D ratio increases. With severe resistance, there is absence and ultimately reversal of end-diastolic flow. These findings are associated with an increased rate of perinatal morbidity and mortality, and a higher likelihood of a long-term poor neurologic outcome. Options for antenatal testing include the non-stress test, contraction stress test, and the biophysical profile. Any of these may be used in a growth-restricted fetus as a means of detecting possible or probable fetal asphyxia. While fetal kick counts may be of value, additional fetal testing such as twice weekly NST with AFI and weekly umbilical artery Doppler studies is indicated in monitoring fetuses with IUGR.