What is the most appropriate next step in the management of this patient who has been referred to you for further evaluation of postmenopausal bleeding and had a recent exam and Pap smear that were normal, a transvaginal ultrasound showing a homogeneous endometrial lining measuring 5.0 mm, and a subsequent office endometrial sample that returned with rare atypical cells?
1) Repeat office endometrial sample
2) Follow-up ultrasound in eight to twelve weeks
3) Return visit in three to six months
4) Abdominopelvic CT scan
5) Dilation and curettage