Detection of ovulation, a review of currently available methods

Abstract

The ability to identify the precise time of ovulation is important for women who want to plan conception or practice contraception. Here, we review the current literature on various methods for detecting ovulation including a review of point-of-care device technology. We incorporate an examination of methods to detect ovulation that have been developed and practiced for decades and analyze the indications and limitations of each-transvaginal ultrasonography, urinary luteinizing hormone detection, serum progesterone and urinary pregnanediol 3-glucuronide detection, urinary follicular stimulating hormone detection, basal body temperature monitoring, and cervical mucus and salivary ferning analysis. Some point-of-care ovulation detection devices have been developed and commercialized based on these methods, however previous research was limited by small sample size and an inconsistent standard reference to true ovulation.

Keywords: family planning; fertility window; ovulation detection.

Figure 1

Transvaginal ultrasonography of ovary and endometrium in early follicular phase (a–c), late follicular (shortly before ovulation) phase (d–f), and post‐ovulatory luteal phase (g–i). In early follicular phase, the endometrium (between the blue arrows) just after menstruation appeared thin and homogenous (a). Multiple small follicles (red arrows) could be seen inside the ovary (c). In late follicular phase, the endometrium was thickened, and a typical “triple line” appearance could be seen (d). A dominant follicle, approximately 2 cm in diameter, is about to ovulate in late follicular phase (f). After ovulation, the endometrium becomes “luteinized,” with increased echogenicity (whitening) (g). The dominant follicle transforms into a corpus luteum (i). Note the increased echogenicity and inhomogenous content (with filament‐like structure) inside the corpus luteum compared to the dominant follicle in picture f. Free fluid can be seen in the pelvis (white arrows in pictures g and f)

Figure 2

An illustration of BBT chart in degrees Celsius. This is a biphasic pattern in a normal ovulatory cycle. Ovulation can only be suggested after observing the rise and plateau of temperature above the purple “Coverline.” A drop in temperature occurs at the end of the luteal phase when progesterone decreases, which is followed by menstruation

Figure 3

(a) The left graph is the photo of Clearblue Easy Fertility Monitor (a) and the Persona (b).60 The right bar chart is the Serum LH surge relative to CPFM peak fertility. The X‐axis −2 and 2 represents >1 day before or after CPFM peak fertility, respectively. Cycles with no CPFM peak fertility (n = 13), no serum LH surge day (n = 10), or neither (n = 1) are excluded from the table.61 (b) The left graph is the illustration of DuoFertility® Sensor worn by patients. The right bar chart is the correlation between ultrasound scans and DuoFertility® result.62 (c) The left graph is the result of ferning patterns by Knowhen Ovulation Monitoring System. (a) Fertile (b) preovulatory (c) postovulatory.63 The accuracy of three proposed algorithms. Algorithm 1 is binarizing + dark pixel density. Algorithm 2 is binarizing + dark pixel density + thinning. Algorithm 3 is binarizing + Hough transform + thinning + decision tree.64 (d) The illustration of possible combination of smartphone ultrasound device and imaging processing algorithms as an ovulation detection device65