Ovulation Predictor Kit (OPK)

Definition - What does Ovulation Predictor Kit (OPK) mean?

An ovulation predictor kit (OPK) is an at-home method for tracking when a woman is most likely to become pregnant by indicating when ovulation is due to occur. OPKs can aid in fertility awareness-based methods (FAM) of family planning when unprotected intercourse is timed to take place during ovulation. Women without standard cycles may not be able to accurately use OPKs, and may require physician assistance to monitor ovulation patterns.

OPKs may also be called fertility monitors or LH surge detectors.

FertilitySmarts explains Ovulation Predictor Kit (OPK)

OPKs test a woman’s urine for the presence of the luteinizing hormone (LH). When levels of LH rise, it is know as the LH surge, which occurs 24-48 hours prior to ovulation.

Prior to the LH surge, the body has been preparing for potential conception. The uterus lining is growing thick an egg is being matured in the ovaries. The egg is encased in a follicle. The LH surge occurs when the brain signals to the ovary that the egg has fully matured. The pituitary gland, a small node at the base of the brain, releases a wave of LH, causing LH surge. The follicle responds to the LH surge by thinning. Eventually the fully matured egg is able to break out of the follicle and begins its descent into the fallopian tube in search of sperm.

For women with standard length cycles (28-32 days) the LH surge occurs between the 12th and 16th day. In this case, monitoring LH levels is possible with an at home ovulation test, called an ovulation predictor kit (OPK). These kits are most accurate when taken in the morning and early afternoon. OPKs are a similar “pee on a stick” method as pregnancy tests.

OPKs are sold in drug stores. They are typically packaged in a set of 5-10. This number of sticks may be necessary, as it may take several days of testing to detect the LH surge. While individual test directions may be different based on brand, each includes directions that indicate how the test is to be taken, and how results are to be read. However, for every test, it is important to note that the morning is the most effective time of day to take the test. Additionally, it is important to not to consume a large volume of liquids prior to taking the test, as it may dilute the urine and invalidate the results.

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