A 33-year-old patient presents with a lack of menstruation since her son was born 18 months ago.
She has no known chronic medical conditions, takes no medications, and had an uncomplicated vaginal birth.
Twenty-four hours after delivery she experienced a postpartum hemorrhage secondary to the retained placenta and was taken to surgery for suction curettage of the uterus to remove the retained tissue. This procedure was uncomplicated and she did not require a blood transfusion. She nursed her child for 12 months postpartum.
After discontinuing nursing, she has not noticed a return of her menstrual cycle and is interested in conceiving another pregnancy soon.
Her thyroid-stimulating hormone is normal. Her body mass index is 26 kg/m2. You prescribe oral estrogen for 2 weeks followed by medroxyprogesterone 10 mg orally for 10 days and she does not have a withdrawal bleed.
Based on the information given, which of the following is the most likely cause for her lack of menses?
This question appears in Med-Challenger OBGYN Exam Review with CME.