DOI: 10.1148/rg.241035027
Detection of Fetal Structural Abnormalities with US during Early Pregnancy1
Katherine W. Fong, MB, BS, FRCPC,
Ants Toi, MD, FRCPC,
Shia Salem, MD, FRCPC,
Lisa K. Hornberger, MD, FRCPC,
David Chitayat, MD, FRCPC,
Sarah J. Keating, MD, FRCPC,
Fionnuala McAuliffe, MD, MRCOG, MRCPI and
Jo-Ann Johnson, MD, FRCSC
1 From the Department of Medical Imaging (K.W.F., A.T., S.S.), Prenatal Diagnosis and Medical Genetics Program (D.C.), Department of Pathology and Laboratory Medicine (S.J.K.), and Department of Obstetrics and Gynecology (F.M., J.J.), Mount Sinai Hospital and University of Toronto, 600 University Ave, Rm 570, Toronto, ON, Canada M5G 1X5; and the Department of Pediatrics, Hospital for Sick Children and University of Toronto (L.K.H.). Presented as an education exhibit at the 2002 RSNA scientific assembly. Received February 4, 2003; revision requested April 9 and received June 19; accepted June 19. All authors have no financial relationships to disclose. Address correspondence to K.W.F. (e-mail: katherine.fong@sympatico.ca).
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Figure 1. Rhombencephalon. Transvaginal US image of a 7.5-week embryo shows a cystic area at the cephalic end (arrow), which represents the rhombencephalic cavity. YS = yolk sac.
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Figure 2a. Normal head at 12 weeks gestation. (a) Axial transabdominal US image of the fetal head shows ossified frontal and parietal bones (arrows) and echogenic choroid plexuses (C) filling the lateral ventricles. (b) Axial US image obtained caudad to a shows the thalamus (T). (c) Coronal US image shows the ossified frontal bone (arrow) and orbits.
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Figure 2b. Normal head at 12 weeks gestation. (a) Axial transabdominal US image of the fetal head shows ossified frontal and parietal bones (arrows) and echogenic choroid plexuses (C) filling the lateral ventricles. (b) Axial US image obtained caudad to a shows the thalamus (T). (c) Coronal US image shows the ossified frontal bone (arrow) and orbits.
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Figure 2c. Normal head at 12 weeks gestation. (a) Axial transabdominal US image of the fetal head shows ossified frontal and parietal bones (arrows) and echogenic choroid plexuses (C) filling the lateral ventricles. (b) Axial US image obtained caudad to a shows the thalamus (T). (c) Coronal US image shows the ossified frontal bone (arrow) and orbits.
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Figure 3a. Acrania and exencephaly at 12 weeks gestation. Coronal (a) and sagittal (b) transvaginal US images of the fetal head show an absent cranial vault and an amorphous mass of neural tissue (arrow). The facial structures and orbits are present.
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Figure 3b. Acrania and exencephaly at 12 weeks gestation. Coronal (a) and sagittal (b) transvaginal US images of the fetal head show an absent cranial vault and an amorphous mass of neural tissue (arrow). The facial structures and orbits are present.
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Figure 4. Encephalocele at 14 weeks gestation. Axial transvaginal US image of the fetal head shows an occipital encephalocele (arrow), with brain tissue herniating through a defect in the occipital bone. The head is microcephalic.
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Figure 5a. Meckel-Gruber syndrome at 12 weeks gestation. (a) Sagittal transabdominal US image of the fetus shows an occipital encephalocele (arrow). (b) Coronal transvaginal US image of the fetal abdomen shows large, echogenic kidneys (cursors). The urinary bladder is not visible. (c) Transvaginal US image of the fetal hand shows postaxial polydactyly (arrow).
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Figure 5b. Meckel-Gruber syndrome at 12 weeks gestation. (a) Sagittal transabdominal US image of the fetus shows an occipital encephalocele (arrow). (b) Coronal transvaginal US image of the fetal abdomen shows large, echogenic kidneys (cursors). The urinary bladder is not visible. (c) Transvaginal US image of the fetal hand shows postaxial polydactyly (arrow).
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Figure 5c. Meckel-Gruber syndrome at 12 weeks gestation. (a) Sagittal transabdominal US image of the fetus shows an occipital encephalocele (arrow). (b) Coronal transvaginal US image of the fetal abdomen shows large, echogenic kidneys (cursors). The urinary bladder is not visible. (c) Transvaginal US image of the fetal hand shows postaxial polydactyly (arrow).
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Figure 6. Lemon sign and ventriculomegaly at 13 weeks gestation. Axial transabdominal US image of the fetal head shows bilateral frontal indentation (arrows) and ventriculomegaly, as evidenced by a dangling choroid plexus (C) and convexity of the lateral wall of the lateral ventricle (arrowheads).
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Figure 7a. Arnold-Chiari malformation with the banana sign and meningomyelocele at 14 weeks gestation. (a) Axial transabdominal US image of the fetal head shows a banana-shaped cerebellum (arrows) and effacement of the cisterna magna (CM). (b) Sagittal US image of the fetal lumbosacral region shows a meningomyelocele (arrow).
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Figure 7b. Arnold-Chiari malformation with the banana sign and meningomyelocele at 14 weeks gestation. (a) Axial transabdominal US image of the fetal head shows a banana-shaped cerebellum (arrows) and effacement of the cisterna magna (CM). (b) Sagittal US image of the fetal lumbosacral region shows a meningomyelocele (arrow).
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Figure 8. Holoprosencephaly at 14 weeks gestation. Coronal transabdominal US image of the fetal head shows fused thalami (T), a monoventricle (M) with virtually no cerebral tissue, and absence of the interhemispheric fissure and falx. Small echogenic choroid plexuses (arrow) are seen on either side of the fused thalami.
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Figure 9a. Dandy-Walker complex at 12 weeks gestation. (a) Axial transvaginal US image of the fetal head shows a cyst (arrow) in the posterior fossa. (b) Coronal transvaginal US image of the fetal mouth shows a bilateral cleft lip (arrows). The fetus had trisomy 13.
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Figure 9b. Dandy-Walker complex at 12 weeks gestation. (a) Axial transvaginal US image of the fetal head shows a cyst (arrow) in the posterior fossa. (b) Coronal transvaginal US image of the fetal mouth shows a bilateral cleft lip (arrows). The fetus had trisomy 13.
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Figure 10. Normal nasal bone ossification at 12 weeks gestation. Transabdominal US image of the fetal facial profile shows ossification of the nasal bone (NB).
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Figure 11. Absent nasal bone ossification at 12 weeks gestation in a fetus with trisomy 21. Transabdominal US image of the fetal facial profile shows no ossification in the expected location of the nasal bone (NB).
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Figure 12. Normal NT thickness at 12 weeks gestation. Sagittal transabdominal US image of the fetus shows an NT thickness of 1.5 mm (cursors). The amnion is seen separately (arrow).
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Figure 13a. Increased NT thickness at 12 weeks gestation associated with trisomy 21. (a) Sagittal transvaginal US image of a fetus with trisomy 21 shows an increased NT thickness of 8 mm (cursors). The skin is elevated along the back due to subcutaneous edema. (b) Photograph of another fetus with trisomy 21 shows a subcutaneous fluid collection at the back of the neck (arrow). (Fig 13b courtesy of Eva Pajkrt, MD, PhD, University College London Hospitals, England.)
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Figure 13b. Increased NT thickness at 12 weeks gestation associated with trisomy 21. (a) Sagittal transvaginal US image of a fetus with trisomy 21 shows an increased NT thickness of 8 mm (cursors). The skin is elevated along the back due to subcutaneous edema. (b) Photograph of another fetus with trisomy 21 shows a subcutaneous fluid collection at the back of the neck (arrow). (Fig 13b courtesy of Eva Pajkrt, MD, PhD, University College London Hospitals, England.)
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Figure 14a. Cystic hygroma and hydrops fetalis in a 13-week fetus with Turner syndrome. (a) Axial transabdominal US image of the fetal neck shows a hygroma with a typical midline septum (arrow). Note the normal cervical spine (S), which helps differentiate a hygroma from a meningocele. (b) Axial US image of the fetal thorax shows a right pleural effusion (arrow) and edema of the skin (arrowheads).
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Figure 14b. Cystic hygroma and hydrops fetalis in a 13-week fetus with Turner syndrome. (a) Axial transabdominal US image of the fetal neck shows a hygroma with a typical midline septum (arrow). Note the normal cervical spine (S), which helps differentiate a hygroma from a meningocele. (b) Axial US image of the fetal thorax shows a right pleural effusion (arrow) and edema of the skin (arrowheads).
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Figure 15. Ventricular septal defect at 12 weeks gestation. Transvaginal US image of the fetal thorax (four-chamber view) shows a small ventricular septal defect (arrowhead) and a small pericardial effusion (arrow). The fetus had trisomy 18, along with an increased NT thickness and an omphalocele.
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Figure 16. Ectopia cordis at 14 weeks gestation. Transvaginal US image of the fetal thorax and upper abdomen shows both ventricles and at least one of the atria protruding from the anterior chest wall. LA = left atrium, LV = left ventricle, RA = right atrium, RV = right ventricle, S = stomach.
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Figure 17a. Left atrial isomerism with complex heart disease at 14 weeks gestation. (a) Axial transabdominal US image of the fetal abdomen shows a left-sided stomach (S) and midline liver (L) with a right-sided descending aorta (Ao) and left-sided azygos vein (Az). (b) Transabdominal US image of the fetal thorax (four-chamber view) shows dextrocardia; the morphologic left ventricle (LV) is on the right side, and the morphologic right ventricle (RV) is on the left side. There is also an atrioventricular septal defect (arrow). Other views showed both great arteries arising from the morphologic right ventricle. M-mode imaging showed a 2:1 atrioventricular block. The fetus developed progressive obstruction of both outflow tracts, complete atrioventricular block, and hydrops fetalis and died in the neonatal period.
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Figure 17b. Left atrial isomerism with complex heart disease at 14 weeks gestation. (a) Axial transabdominal US image of the fetal abdomen shows a left-sided stomach (S) and midline liver (L) with a right-sided descending aorta (Ao) and left-sided azygos vein (Az). (b) Transabdominal US image of the fetal thorax (four-chamber view) shows dextrocardia; the morphologic left ventricle (LV) is on the right side, and the morphologic right ventricle (RV) is on the left side. There is also an atrioventricular septal defect (arrow). Other views showed both great arteries arising from the morphologic right ventricle. M-mode imaging showed a 2:1 atrioventricular block. The fetus developed progressive obstruction of both outflow tracts, complete atrioventricular block, and hydrops fetalis and died in the neonatal period.
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Figure 18. Physiologic herniation of the midgut at 10 weeks gestation. Transvaginal US image shows a small (4-mm-diameter) echogenic mass at the base of the umbilical cord (arrow) as it enters the fetal abdomen (A).
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Figure 19. Omphalocele at 12 weeks gestation. Axial transabdominal US image of the fetal abdomen shows a 1.7-cm-diameter mass (arrow), which has herniated through a defect in the anterior abdominal wall. It contains the liver (L) and stomach (S). The fetus had trisomy 18, as well as multiple anomalies.
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Figure 20a. Gastroschisis and skeletal dysplasia at 13 weeks gestation. (a) Sagittal transabdominal US image of the fetus shows free-floating bowel loops (arrow), which have herniated through a defect in the anterior abdominal wall. The NT thickness is 5 mm (cursors). (b) Axial transabdominal US image of the fetal abdomen shows the insertion of the umbilical cord (curved arrow), which is to the left of the bowel loops (straight arrow). S = stomach. (c) Transabdominal US image shows the femur, which is 7 mm long (cursors), below -4 standard deviations for gestation. All of the long bones were abnormally short. Bilateral clubfoot was also seen. These findings were confirmed at pathologic examination; the skeletal dysplasia was a form of chondrodysplasia punctata.
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Figure 20b. Gastroschisis and skeletal dysplasia at 13 weeks gestation. (a) Sagittal transabdominal US image of the fetus shows free-floating bowel loops (arrow), which have herniated through a defect in the anterior abdominal wall. The NT thickness is 5 mm (cursors). (b) Axial transabdominal US image of the fetal abdomen shows the insertion of the umbilical cord (curved arrow), which is to the left of the bowel loops (straight arrow). S = stomach. (c) Transabdominal US image shows the femur, which is 7 mm long (cursors), below -4 standard deviations for gestation. All of the long bones were abnormally short. Bilateral clubfoot was also seen. These findings were confirmed at pathologic examination; the skeletal dysplasia was a form of chondrodysplasia punctata.
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Figure 20c. Gastroschisis and skeletal dysplasia at 13 weeks gestation. (a) Sagittal transabdominal US image of the fetus shows free-floating bowel loops (arrow), which have herniated through a defect in the anterior abdominal wall. The NT thickness is 5 mm (cursors). (b) Axial transabdominal US image of the fetal abdomen shows the insertion of the umbilical cord (curved arrow), which is to the left of the bowel loops (straight arrow). S = stomach. (c) Transabdominal US image shows the femur, which is 7 mm long (cursors), below -4 standard deviations for gestation. All of the long bones were abnormally short. Bilateral clubfoot was also seen. These findings were confirmed at pathologic examination; the skeletal dysplasia was a form of chondrodysplasia punctata.
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Figure 21. Normal kidneys at 13 weeks gestation. Coronal transvaginal US image of the fetal abdomen shows normal kidneys (cursors). Fluid is seen in the renal pelves (arrowheads).
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Figure 22a. Multicystic dysplastic kidney. (a) Sagittal transabdominal US image of a fetus at 14 weeks gestation shows several cysts (arrow) in a slightly enlarged kidney (cursors). (b) Follow-up transabdominal US image obtained at 18 weeks gestation shows multiple cysts (arrows) in the enlarged kidney (cursors).
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Figure 22b. Multicystic dysplastic kidney. (a) Sagittal transabdominal US image of a fetus at 14 weeks gestation shows several cysts (arrow) in a slightly enlarged kidney (cursors). (b) Follow-up transabdominal US image obtained at 18 weeks gestation shows multiple cysts (arrows) in the enlarged kidney (cursors).
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Figure 23a. Cloacal exstrophy at 14 weeks gestation. (a) Sagittal transabdominal US image of the fetal lower abdomen shows an irregular mass (arrows) arising from the anterior abdominal wall. The bladder is not seen. There is mild hydronephrosis (H). (b) Postmortem photograph of the fetus at 15 weeks gestation shows a defect in the anterior abdominal wall below the umbilicus (U) and an irregular mass of exposed intestine and exstrophied bladder (arrows). No intact bladder, external genitalia, or anus can be identified.
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Figure 23b. Cloacal exstrophy at 14 weeks gestation. (a) Sagittal transabdominal US image of the fetal lower abdomen shows an irregular mass (arrows) arising from the anterior abdominal wall. The bladder is not seen. There is mild hydronephrosis (H). (b) Postmortem photograph of the fetus at 15 weeks gestation shows a defect in the anterior abdominal wall below the umbilicus (U) and an irregular mass of exposed intestine and exstrophied bladder (arrows). No intact bladder, external genitalia, or anus can be identified.
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Figure 24. Megacystis at 12 weeks gestation. Sagittal transabdominal US image of a male fetus shows a distended thick-walled bladder (arrow), which is 13 mm long. It did not empty during a 30-minute examination. There was no hydronephrosis. At subsequent US examinations, the bladder remained large, but it was seen to empty partially on several occasions when the observation was prolonged (up to 1 hour). Postnatal US showed a large bladder (no thickening or trabeculation) and normal kidneys. Voiding cystourethrography performed at 3 months of age showed a large bladder (which accepted 100 mL of contrast material), a diverticulum in the proximal urethra, and bilateral vesicoureteric reflux. Further follow-up is not yet available.
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Figure 25. Clubfoot and polydactyly at 14 weeks gestation. Transabdominal US image shows varus deformity of the foot (arrow) and six toes.
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Figure 26. Jarcho-Levin syndrome at 13 weeks gestation. Sagittal transabdominal US image of the fetus shows major ossification and segmentation errors of the thoracolumbar spine (arrows).
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Figure 27. Dichorionic diamniotic twins at 13 weeks gestation. Axial transabdominal US image of the uterus shows the twin peak sign (arrow). P = single placental mass due to contiguous or fused placentas.
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Figure 28. Monochorionic diamniotic twins at 12 weeks gestation. Axial transabdominal US image of the uterus shows a thin intertwin membrane (arrow). P = single placenta.
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Figure 29. Conjoined twins at 12 weeks gestation. Transvaginal US image shows two fetuses joined at the chest (C) and abdomen (A). A thick NT with septa (arrow) is seen in both fetuses.
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Figure 30a. Complete hydatidiform mole with a coexistent fetus at 13 weeks gestation. (a) Axial transabdominal US image of the uterus shows a large posterior hydatidiform mole (M), a separate anterior placenta (P), and a live fetus (F). (b) Photograph of the curettage specimen shows multiple grapelike vesicles (hydropic villi) up to 9 mm in diameter (arrows). Immunostaining for p56 kiP2 indicated a dual genetic population of chorionic villi, thus confirming the diagnosis of a twin gestation: a complete hydatidiform mole and a normal fetus.
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Figure 30b. Complete hydatidiform mole with a coexistent fetus at 13 weeks gestation. (a) Axial transabdominal US image of the uterus shows a large posterior hydatidiform mole (M), a separate anterior placenta (P), and a live fetus (F). (b) Photograph of the curettage specimen shows multiple grapelike vesicles (hydropic villi) up to 9 mm in diameter (arrows). Immunostaining for p56 kiP2 indicated a dual genetic population of chorionic villi, thus confirming the diagnosis of a twin gestation: a complete hydatidiform mole and a normal fetus.
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Copyright © 2004 by the Radiological Society of North America.
