Prenatal Diagnosis Of Congenital Anomalies

Eunice Kennedy Shriver National Institute Of Child Health & Human Development

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Abstract

Quantifying calcium changes in the fetal spine using quantitative susceptibility mapping as extracted from STAGE imaging (1) Even though ultrasound is the standard method to image the fetus, it has limitations, e.g., characterizing the state of mineralization of the fetal spine. Computer tomography (CT) could be considered an alternative, but it carries the risk of ionizing radiation to the fetus and the mother. The fetal skeletal bone development during pregnancy has been qualitatively described by different imaging modalities, yet there is a paucity of quantitative evidence of bone development as a function of gestational age in the second and third trimesters. Similar to iron, calcium in the bones also induces severe-phase dephasing at longer echo times. However, as opposed to iron, which is paramagnetic with positive susceptibility, calcium is diamagnetic, meaning that it shows a negative susceptibility. Quantitative susceptibility mapping (QSM) has also been introduced as an in vivo non-ionizing imaging alternative to CT from which bone calcification can be monitored and quantified longitudinally over the course of pregnancy. We have successfully evaluated the susceptibility of the fetal spine and demonstrated a strong decreasing susceptibility with gestational age. For the first time, our results have been able to evaluate changes in fetal bone calcification over time. The role of the placenta in spontaneous preterm labor and delivery with intact membranes (2) Preterm birth is the leading cause of death in children younger than 5 years of age. It accounts for 35% of deaths in neonates and affects 10.6% of live births. Infants who survive a preterm birth have a higher rate of long-term morbidity, including neurologic and developmental disabilities, and a shorter life expectancy compared to infants born full term. Fetal nutrition depends on the blood flow and its circulation on the maternal and fetal sides of the placenta. Therefore, an important pathway whereby the placenta causes non-infection/inflammation-related complications of pregnancy must involve abnormalities of the fetoplacental circulation that impair the exchange function of the placenta. This study was conducted to determine whether placental vascular pathology and impaired placental exchange (due to maturational defects) are involved in the etiology of spontaneous preterm labor and delivery in cases without infection/inflammation, i.e., without histologic acute chorioamnionitis. An evaluation was performed for 184 cases of pregnancies resulting in spontaneous preterm labor and delivery (<37 weeks of gestation) and for 2471 controls in uncomplicated pregnancies that delivered fetuses at term (3742 weeks of gestation). We found that the frequency of maternal blood flow abnormalities represented pathologically as lesions of maternal vascular malperfusion was greater in the placentas of patients with preterm labor than in the control group 14.1% (26/184) vs. 8.8% (217/2471). Likewise, placental developmental abnormalities termed as disorders of villous maturation were more frequent in the group with preterm labor (41.1%; 39/95) than in the control group: delayed villous maturation: 31.6% (30/95) of cases vs. 2.5% (13/519) of controls; accelerated villous maturation: 9.5% (9/95) of cases vs. 0% of controls. We demonstrated that maturational defects of placental villi contributed to unexplained spontaneous preterm labor and delivery of appropriate-for-gestational-age fetuses in the absence of acute inflammatory lesions of the placenta.