A 41-year-old woman, G2P1, comes to the physician for her first prenatal visit. Her last menstrual period was 16 weeks ago. Examination shows a uterine fundus that is palpated midway between the pubic symphysis and umbilicus. Her serum α-fetoprotein is 2.4 times the upper limit of normal. Which of following is the most appropriate next step in management?
Measurement of β-hCG, estriol, and inhibin A
Non-stress test
Pap smear
Repeat α-fetoprotein measurement
Ultrasonography
