At the end of each explained answer, there is a number combination in parentheses. The first number identifies the reference source; the second number or set of numbers indicates the page or pages on which the relevant information can be found.
1. (A) This is a surface-rendered image. (1:90)
2. (D) None of the above. This is a normal 12-week fetus whose abdominal wall is intact after physiologic herniation of bowel that was completed one week earlier. (1:90)
3. (D) None of the above. See explanation in answer 2. (1:90)
4. (C) None of the above. See explanation in answer 2. (1:90)
5. (A) This is a surface-rendered image taken in the midsagittal plane. (2:687)
6. (A) This is the corpus callosum, which forms from posterior to anterior. (2:687)
7. (D) None of the above. See explanation in answer 6. (2:687)
8. (C) Cannot tell the position of the fetus. (2:687)
9. (C) This is a coronal image of normal kidneys. (2:687)
10. (A) Normal. See explanation in answer 9. (2:687)
11. (D) The kidneys are enlarged and echogenic due to multiple dilated renal tubules. (2:687)
12. (A) Cannot be seen in their entirety. It is difficult to delineate the entire ureter on 3D. (2:267)
13. (D) This fetus is normal. (1:113)
14. (D) The cleft lip is best shown on 3D. (1:113)
15. A cleft lip is usually an isolated anomaly but can be associated with a sporadic karyotypic abnormality. (1:113)
16. (A) Transparency mode is used to delineate bony abnormalities. (1:90)
17. (A) This 3D sonogram of the umbilical cord shows two umbilical arteries and one umbilical vein. (1:99)
18. (D) All can be associated with a single umbilical artery. (1:99)
19. (A) The tightness of the coil of the umbilical cord is related to fetal movement in utero. (1:99)
20. (D) 3D is helpful in all of these. (1:99)
21. (D) These are normal feet and toes. (1:98)
22. (D) All of these are associated with a club foot. (1:116)
23. (D) See answer to question 22. (1:116)
24. (A) 3D is helpful in showing the relationship of the long bones of the leg to the foot. (1:116)
25. (C) There is a large marginal sinus hemorrhage. (1:138)
26. (B) This can severely compromise fetal well-being. (1:138)
27. (C) Both conditions may result in retroplacental hemorrhage. (1:138)
28. (C) Both are important parameters. (1:138)
29. (D) This fetus has anencephaly; none of the choices is correct. (1:111)
30. (C) The alpha-fetoprotein level is decreased. (1:111)
31. (A) Anencephaly is thought to be a true result of failed closure of the anterior neuropore. (1:111)
32. (A) Anencephaly is an example of a neural tube defect. Meningomyelocele is another. (1:111)
33. (A) This is an omphalocele. (1:115)
34. (D) Omphaloceles may be associated with all of the conditions listed. (1:115)
35. (A) Gastroschisis involves eccentric herniation of the umbilical cord from a weakening in the right side of the cord insertion. It is usually an isolated defect. (1:115)
36. (A) Omphaloceles may involve liver and bowel. (1:115)
37. (B) This shows labia major on a female fetus. (1:100)
38. (A) It may be helpful to diagnose a specific karyotypic abnormality. (1:100)
39. (C) Hypospadias involves abnormal penile opening of the urethra and can be associated with renal anomalies and hydronephrosis. (1:115)
40. (A) Surface rendering best shows external genitalia. (1:115)
41. (B) This is an ovarian mass with a papillary excrescence. (1:45)
42. (A) Low-level echoes are arising from hemorrhage. (1:45)
43. (A) The wall has a large papillary excrescence. (1:45)
44. (A) Papillary excrescences are frequently seen in borderline serous ovarian cystadenoma (1:45)
45. (A) This shows a polyp. (1:61)
46. (D) All of these may be associated with a polyp. (1:61)
47. (D) They can be removed hysteroscopically with polyp forceps. If there is a pedunculated submucosal fibroid, wire-loop resection is typically performed. (1:61)
48. (B) Polyps typically contain tiny cystic spaces representing glandular elements. (1:61)
49. (A) This is an endometrial polyp. (1:61)
50. (A) Low. Only 3% of polyps are cancerous. (1:61)