To the Editor:

In the article written by Dr. Phillips and colleagues, they describe a suggested workup for women suspected of having anovulation.¹ The article recommends that clinicians obtain a day-21 progesterone level, and for levels less than 3 ng per mL (9.54 nmol per L), conclude that ovulation has not occurred. This method leaves out a group of people with a longer menstrual cycle. If a woman has a 35-day menstrual cycle, she may not ovulate until day 21 or 22; therefore, a day-21 progesterone level would be falsely low. The algorithm should recommend a midluteal progesterone level that would allow clinicians to discuss cycle specifics with their patients and determine which day would be the most accurate time to obtain a progesterone level. The American Society for Reproductive Medicine states, “Given the range of normal variation in ovulatory cycles, a serum progesterone measurement generally should be obtained approximately 1 week before the expected onset of the next menses, rather than on any one specific cycle day (e.g., cycle-day 21).”²

The article also states that the American College of Obstetricians and Gynecologists no longer recommends the examination of cervical mucus in infertility evaluation. Upon review of the cited reference, I could not find any such recommendation.³ On the contrary, the American Society for Reproductive Medicine states that cervical fluid tracking is an inexpensive method with moderate-quality evidence for increasing the likelihood of achieving pregnancy: “A retrospective cohort study involving 1,681 cycles observed that pregnancy rates were highest (approximately 38%) when intercourse occurred on the day of peak mucus (day 0) and appreciably lower (approximately 15% to 20%) on the day before or after the peak.”⁴

During a time when many patients feel a loss of control and lack of understanding, we can tailor infertility care and empower patients to understand more about their bodies.

In Reply:

This article was intended to serve only as a framework for the infertility workup. We agree that a patient with a longer menstrual cycle may have spuriously low progesterone levels at day 21. There are always patient-specific characteristics for which few algorithms can adequately account. We advise that the recommendations be adjusted as needed to address specific situations.

The sentence, “However, evaluation of cervical mucus is no longer routinely used in infertility evaluation” is from information provided in reference 10 and not 11, as incorrectly cited in the article. The article has been corrected online. We did not intend to suggest that cervical mucus screening cannot be used for certain patients; however, routine postcoital cervical mucus testing is not recommended by the American Society for Reproductive Medicine in the initial workup of infertility.¹