Ovulation detection methods

1. Menstrual history is often all that is required. A well-documented clinical diagnosis of oligomenorrhea or amenorrhea warrants therapy without further testing. Conversely, while clinical symptoms of ovulation such as mittelschmerz (midcycle discomfort associated with ovulation) and moliminal signs are reassuring, more objective data are necessary to confirm ovulation.

2. Basal body temperature (BBT) charting is inexpensive and can be useful to retrospectively confirm regular ovulatory cycles as indicated by a sustained rise in temperature above baseline for at least 11 days. The rise in temperature coincides with increased circulating progesterone secreted from the corpus luteum. However, BBT charting has significant limitations because the temperature rise occurs 1 to 2 days after ovulation and some ovulatory women have monophasic BBT patterns.

3. Serum progesterone levels greater than 3ng/mL infer that ovulation has occurred. However, progesterone levels above 10ng/mL may be associated with greater reproductive potential. Because progesterone peaks during the midluteal phase, the best time to assay progesterone levels are 7 to 10 days after ovulation. The timing of the midluteal progesterone level should be based on objective data such as a BBT chart or an ovulation predictor kit and not arbitrarily assessed on cycle day 21 or 23. For example, a woman who has a 35-day menstrual cycle is likely to ovulate on cycle day 21 and her progesterone level on the day of ovulation will invariably be 10ng/mL. This only suggests that the patient received poor instructions not poor luteal phase function.

4. Urinary luteinizing hormone detection kits are the most cost-effective means to prospectively predict ovulation in spontaneously cycling women. These kits are available over the counter and are commonly known as ovulation predictor kits. Because the LH surge may only last 36 hours, it is important to test at the same time each day. Depending on the sensitivity and accuracy of a particular kit (not all ovulation predictor kits are created equal), detection of LH in the urine provides patients with a convenient signal of the day of and just prior to ovulation, which are the days that conception is most likely.

5. Endometrial biopsy has been used to confirm ovulation by looking for distinct histologic changes in the endometrium that occur only after the proper sequence of exposure to estradiol then progesterone. This test is relatively expensive and debate continues as to its relevancy in the evaluation and treatment of infertility patients.

6. Serial ultrasound measurements of ovarian follicle growth and collapse provide good presumptive evidence of ovulation but this method is expensive, time-consuming, and rarely necessary.

Quality of ovulation and measurements of fertility potential have been created in an attempt to evaluate the effectiveness or probability of success with or without various treatment regimens. Although the only true measure of egg quality is the delivery of a healthy child, several indirect measures of ovarian function are often useful in counseling patients when they are considering treatment options. For example, if a preliminary test suggests that the probability of having a live birth is <5%, the patient may not want to spend $10,000 on fertility treatments for such poor odds of success.

1. Serum progesterone levels <10ng/mL, when appropriately timed, may indicate ovulatory dysfunction and warrant treatment with clomiphene. When patients are receiving clomiphene citrate as treatment, progesterone levels >15ng/mL are desirable. Serum progesterone levels can vary widely during the day and are worth repeating when low and timed appropriately.

2. Day 3 follicle-stimulating hormone (FSH) levels along with serum estradiol have been used to estimate fertility potential, also called ovarian reserve. In simplistic terms, high FSH levels indicate that the brain is working harder in an attempt to stimulate egg production. An elevated day 3 FSH is a sign of diminished ovarian reserve, which suggests poor pregnancy rates for a woman with any form of fertility treatment that relies on the use of her own eggs. The actual level of FSH that is considered high depends mainly on the assay methodology. In laboratories that use an automated chemiluminescence system, an FSH >10mIU/mL usually signifies diminished ovarian reserve. It should be noted that a low FSH level does not imply an increased likelihood of pregnancy. For example, a 40-year-old woman with a day 3 FSH of 4mIU/mL has the same low chances of pregnancy as any other 40-year-old woman.

3. Clomiphene citrate challenge test (CCCT) is an extension of the day 3 FSH level. Day 3 FSH and estradiol levels are obtained. Clomiphene citrate 100 mg is administered on cycle days 5 to 9 and the FSH level is repeated on day 10. The prognostic results are based upon the highest (worst) FSH value. The CCCT is felt to be more sensitive than a day 3 FSH since up to 40% women with a normal day 3 FSH will have an elevated day 10 FSH.