Ultrasound in the First Trimester and Earlier: How to Keep It Safe -- Ultrasound and Infertility -- Maternal Comorbidities and First-Trimester Ultrasound Examination -- First-Trimester Embryology: An Overview -- Elements of Teratology -- First-Trimester Ultrasound: Guidelines -- Normal First Trimester Pregnancy -- Aneuploidy Screening: The Ongoing Role of First-Trimester Ultrasound -- Fetal Biometry in Early Pregnancy -- Threshold, Discriminatory Zone, and "The New Rules" -- The Fetal Heart in Early Pregnancy -- Doppler Sonography in Early Pregnancy -- Three-Dimensional Ultrasound: A Role in Early Pregnancy? -- Multiple Gestations-Multiple Headaches -- First-Trimester Ultrasound: Early Pregnancy Failure -- Ectopic Pregnancy: Pregnancy of Unknown Location (PUL) -- A Consequence of Cesarean Delivery: First-Trimester Cesarean Scar Pregnancy -- First-Trimester Ultrasound in Gestational Trophoblastic Disease -- The First Trimester Fetal Brain -- The First Trimester Fetal Face and Neck -- The First TrimesterFetal Gastrointestinal Tract -- The First Trimester Fetal Genitourinary Tract -- The First Trimester Fetal Skeletal System -- Invasive procedures -- Diagnosis of Fetal Genetic Syndromes in the First Trimester -- Pelvic masses -- The role of 3D imaging for Congenital Mullerian Malformations in the First Trimester.