医学影像学课件：Gynaecology and Obstetrics.ppt

The yolk sac appears slightly enlarged The amnion is clearly visible. There was no cardiac activity by the M-Mode examination Large empty distorted intrauterine sac that is bulging toward the cervical canal Second and third trimesters of pregnancy Level of biparietal diameter demonstrates the paired thalami (large arrows) with the slit-like third ventricle between them (small arrows) Axial view of the normal cerebellum Eyes, nose and lips Second and third trimesters of pregnancy Spine. Longitudinal image of entire spine demonstrates parallel alignment of posterior ossification centers until they converge at the sacrum (arrow). Transverse view at the level of the four-chamber view of the heart demonstrates homogeneous lung tissue (arrows) filling the thorax around the heart (arrowhead). Second and third trimesters of pregnancy Transverse view of the abdomen at the level of the stomach (S) and intrahepatic portion of the umbilical vein (arrowhead) as it joins the left portal vein. The spine (SP) is seen in transverse posteriorly. Transverse view of the fetal abdomen at the level of the umbilical cord insertion (arrow) demonstrates an intact anterior abdominal wall. Transverse view of the fetal abdomen demonstrates a kidney (arrows) on either side of the spine (SP). Congenital Fetal Abnormalies Anencephaly Cephalocele Spina bifida Hydrocephaly Esophageal atresia Nonfetal abnormalities Placental abnormality Normal placente Placental abruption and Hematoma A collection of hypoechoic fluid lifts the edge of the placenta (P) away from the underlying myometrium (M). The fluid collection contains layering high-attenuation material (arrowhead), a finding consistent with blood. Placental abruption with retroplacental hematoma. There is a hypoechoic hematoma (long arrow and calipers) lifting the edge of the placenta (short arrow). Placenta previa (L)Transvaginal US image obtained at 20 weeks gestation shows a low-lying placenta (P). The placental margin comes to within