The World Health Organization defines abortion as any spontaneous or induced pregnancy termination prior to how many weeks’ gestation?
Approximately what percentage of first-trimester abortions is anembryonic, that is, with no identifiable embryonic elements?
Most early pregnancy losses are clinically silent. Highly sensitive maternal serum β‑human chorionic gonadotropin assays indicate approximately what percentage of pregnancies is lost after implantation?
More than 80 percent of spontaneous abortions occur in the first 12 weeks of pregnancy. What percentage of first-trimester abortions results from chromosomal anomalies?
Which of the following chromosomal anomalies is most frequently identified with first-trimester abortion?
d. Balanced robertsonian translocation
Monosomy X (45,X) is the single most common specific chromosomal abnormality in abortuses. Cystic hygromas, shown here at the fetal neck, are a common sonographic finding with this syndrome and carry a poor prognosis. This syndrome is known by what eponym?
d. Wolf–Hirschhorn syndrome