A 28-year-old woman visits her gynecologist for a routine check-up. She reports that she and her partner have been trying to conceive for the past 6 months without success. She has regular menstrual cycles with a duration of 30 days. She denies any history of pelvic pain or abnormal bleeding. Past medical history is unremarkable. She takes a prenatal vitamin daily. Vital signs are within normal limits. Pelvic examination is unremarkable. Transvaginal ultrasound shows no abnormalities.
In a normal pregnancy, during which phase of the menstrual cycle does the blastocyst typically implant?
The correct answer is:
B) Luteal phase
In a normal menstrual cycle, the blastocyst typically implants into the endometrium during the luteal phase. This phase follows ovulation and is characterized by increased progesterone levels, which support the endometrium for potential implantation and pregnancy.
Answer choice A: Follicular phase, is incorrect. The follicular phase precedes ovulation and is characterized by follicle growth in the ovary in response to follicle-stimulating hormone (FSH).
Answer choice C: Menstruation, is incorrect. Menstruation occurs during the early part of the menstrual cycle when the endometrium sheds if fertilization and implantation do not occur.
Answer choice D: Ovulation, is incorrect. Ovulation marks the release of the mature egg from the ovary, typically occurring midway through the menstrual cycle.
Answer choice E: Proliferative phase is incorrect. The proliferative phase follows menstruation and is characterized by endometrial growth and thickening in response to estrogen.
Key Learning Point
In a normal menstrual cycle, the blastocyst typically implants into the endometrium during the luteal phase, which follows ovulation and is characterized by increased progesterone levels.
