CASE 22
History: A woman presents with uncertain menstrual dates in the late first trimester for evaluation of embryonic age.
1. What should be included in the differential diagnosis of Figure A? (Choose all that apply.)
A. Normal-appearing embryo with a crown-rump configuration
D. Dichorionic diamniotic twins
2. In the first trimester, what are the ultrasound findings to determine that a twin gestation is dichorionic-diamniotic (Di-Di)?
A. One sac with a membrane greater than 2 mm within
B. Two separate sacs and an interposed membrane greater than 2 mm
C. Two separate sacs and no interposed membrane
D. One sac with no interposed membrane
3. What is a problem of conjoined twins at birth?
A. Cesarean delivery is required.
B. Immediate intubation is required.
C. Maternal hemorrhage is a significant complication.
D. Preterm delivery is required.
4. What percentage of twins are fraternal?
A. 50%
B. 80%
C. 20%
D. 1%
