A 22-year-old woman, 14 weeks pregnant, visits her doctor for a prenatal appointment. She claims to be in good health, with the exception of occasional moderate weariness. So far, her pregnancy has been trouble-free. The patient's abdomen seems bigger than would be expected at 14 weeks on physical examination. An obstetrical ultrasound reveals male and female twins. Which of the following best defines this patient's form of twin placentation?

Question

Quizplus · Accepted Answer

Eductional Objective: Dizygotic twins are formed when two oocytes are fertilized by two separate sperm, can be of different sexes, and virtually invariably have two chorions and two amnions (eg, dichorionic/diamniotic). Monozygotic twins, on the other hand, are the same sex, result from the fertilization of a single oocyte, and can be dichorionic/diamniotic (days 0-4), monochorionic/diamniotic (days 4-8), monochorionic/monoamniotic (days 8-12), or monochorionic/monoamniotic conjoined twins (> 13 days).

A 22-Year-Old Woman, 14 Weeks Pregnant, Visits Her Doctor for a Prenatal