What are the indicators of ovulation?

Ovulation is invariably followed by formation of corpus luteum and progesterone secretion. Tests for ovulation are essentially tests for confirming an increased progesterone secretion during the postovulatory phase.

While these can be confirmed by direct hormonal assay or endometrial biopsy, two simple methods are the basal body temperature charting and the cervical mucus test, (i) Basal body temperature charting. Progesterone is associated with a 0.2°C-0.5°C rise in basal body temperature, which occurs immediately following ovulation and which persists during most of the luteal phase.

The basal body temperature dips during the follicular phase. This temperature increment is used clinically as an index of ovulation, (ii) Cervical mucus test. The cervical epithelium secretes a watery mucus in response to estrogen stimulation. During the preovulatory phase, estrogen makes the cervical mucus thinner and more alkaline.

The mucus is thinnest at the time of ovulation, and its elasticity, or spinnbarkheit, increases so much that by mid-cycle, a drop can be stretched into a 8-12 cm long, thin thread. In addition, it dries in an arborizing, fern-like pattern when a thin layer is spread on a slide. In the postovulatory phase, progesterone makes the cervical mucus thick, tenacious, and cellular.

It fails to form the fern pattern on drying and the spinnbarkheit is no longer possible. Anovulatory cycles are indicated by the persistence of spinnbarkheit and fern pattern.