FCOG-1148

A 26-year-old woman had a history of dilation and curettage for septic abortion. Currently, she has developed amenorrhea for 6 months already. It was also noted that she smokes 10 cigarettes and drinks 2 standard alcoholic drinks every day. She was tested for beta-hCG but it was not detectable.

Which of the following is considered the most appropriate next step to establish a diagnosis?