Chorionicity and Amnionicity in Twins
KEY FACTS Terminology • 70% dizygotic : 2 ova fertilized by different sperm; therefore, all are dichorionic • 30% monozygotic : Single ovum fertilized by single sperm, which then divides…
Trisomy 13
KEY FACTS Imaging • Holoprosencephaly is hallmark anomaly ○ Spectrum of severity: Alobar, semilobar, lobar ○ Associated facial anomalies – Close-set orbits (hypotelorism), fused eyes (cyclopia) – Small nose, proboscis…
Myoma in Pregnancy
KEY FACTS Terminology • Fibroid, leiomyoma • Definition: Benign smooth muscle tumor of uterus Imaging • Typically well-defined round or oval hypoechoic mass ± calcification • Myomas can grow during…
Müllerian Duct Anomalies in Pregnancy
KEY FACTS Terminology • Spectrum of congenital uterine malformations ○ 20% unicornuate : Single uterine horn ± rudimentary horns ○ 5% uterus didelphys : 2 separate horns, 2 cervices –…
Trisomy 18
KEY FACTS Terminology • Autosomal trisomy of chromosome 18 (T18) Imaging • Hallmark finding: Multiple anomalies ○ No single anomaly is hallmark of T18 • Most cases with findings at…
Twin-Twin Transfusion Syndrome
KEY FACTS Terminology • Monochorionic (MC) twin complication caused by intrauterine transfusion of blood from donor twin to recipient twin via arteriovenous placental anastomoses Imaging • Hallmark finding is oligohydramnios…
Cytomegalovirus
KEY FACTS Imaging • Fetal growth restriction • Brain findings ○ Microcephaly (up to 27%) ○ Ventriculomegaly (moderate to severe in 45%) – Intraventricular adhesions, abnormal periventricular echogenicity – Periventricular/parenchymal…
Germinal Matrix Hemorrhage
KEY FACTS Imaging • Germinal matrix hemorrhage (GMH) most common at caudothalamic (CT) groove in vascular germinal matrix • Grading system ○ Grade 1 : GMH only with globular echogenic…
VACTERL Association
KEY FACTS Imaging • Nonrandom association of 6 core abnormalities ○ V ertebral defects – Hemivertebrae: Best demonstrated in coronal plane, scoliosis originates at hemivertebra(e) – Fusion of vertebral bodies…
Amniotic Band Syndrome
KEY FACTS Terminology • Controversial as to etiology, but simplest concept is entrapment of fetal parts by disrupted amnion Imaging • Asymmetric distribution of bizarre “slash” defects is hallmark of…
