American Board of Family Medicine (ABFM) Practice Exam

In the context of evaluating infertility, particularly in a patient with regular menstrual cycles and a normal sperm analysis, the next logical step is to assess the luteal phase of the menstrual cycle for ovulatory function. The luteal phase is crucial for successful implantation of an embryo, and a luteal-phase progesterone test can provide insight into whether ovulation is occurring adequately.

Progesterone is produced by the corpus luteum after ovulation, and its levels should rise in the luteal phase. If the progesterone level is insufficient, it may indicate a problem with ovulation, such as luteal phase deficiency, which could contribute to difficulty in conceiving. Therefore, measuring the luteal-phase progesterone levels can help determine if the hormone production is adequate for maintaining a potential pregnancy.

While other tests might be useful in a broader infertility workup, in this specific scenario with the patient's regular periods and normal sperm analysis, checking the luteal-phase progesterone is a vital step to ensure that implantation conditions are being met. It focuses directly on potential ovulatory issues, which is particularly pertinent in this clinical picture.