In a postcoital test, the characteristics of a woman's cervical mucus are evaluated to determine how the sperm and muscus are interacting. Specifically, the following characteristics of the cervical mucus are evaluated:
- Ferning - When the cervical mucus dries on a microscope slide, it should take on the appearance of ferns. This assures that the mucus has been exposed to adequate levels of estrogen exactly at the time of ovulation and without any exposure to progesterone.
- Amount of cervical mucus - There should be a lot of cervical mucus production just prior to and at the time of ovulation.
- Clarity - The cervical mucus should be very clear, almost watery.
- Cellularity - There should be relatively few cells present, other than sperm.
- Spinnbarkeit - This is the stretchiness of the cervical mucus. It should be almost elastic and may stretch 10 cm or more.