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Friday, April 6, 2007

Ovulation -- Detection

The initial infertility evaluation should always try to document ovulation. This can not always be done with absolute certainty. The human egg is microscopic. This means that it is invisible to the naked eye and cannot be seen without the aid of a microscope. Therefore, when you think about it the only real way to absolutely confirm the egg's release from the ovary is to achieve a pregnancy or to identify the egg under the microscope after flushing the microscopic egg out from the pelvis, fallopian tube or uterus (which is possibly immoral and certainly both impractical and difficult).

Useful methods of documenting ovulation

1. Obtaining the history of regular menstrual cycle intervals off all medication.

This is the oldest technique of documenting ovulation and it is both simple and fairly reliable. Additional support occurs if each menstrual flow is consistent in amount, there are premenstrual symptoms reflecting that hormonal shifts are occurring, and the menstrual intervals have been regular for a long period of time (eg., years). It should be confirmed that the cycle intervals are regular off all medication since some medications regulate the menstrual cycle (such as birth control pills).

2. The basal body temperature (BBT) record

This is another potentially useful source of information about ovulation. A woman's early morning temperature increases a little more than a half degree Fahrenheit after ovulation due to the effect of increased progesterone on her temperature regulator (which is in the hypothalamus of the brain). Typically, the woman's temperature rises from less than 98 degrees (prior to ovulation) to greater than 98 degrees (after ovulation). The classic biphasic pattern on the BBT record is good supportive evidence that ovulation is occurring. Unfortunately, up to 10% of women may not have a biphasic BBT record despite regular ovulation.

3. Cervical mucus characteristics

The cervical mucus is strongly influenced by estrogen and progesterone. The most commonly noted changes that can be seen by a woman include amount and elasticity (stringy quality) of the mucus. Just prior to ovulation, there is abundant elastic clear mucus at the cervix, the time of "maximal wetness." In my experience, there are only a relatively small handful of women sufficiently motivated to consistently check for changes in mucus. Although popular in some circles, I have not encouraged use of this method of detecting ovulation

4. Ovulation predictor kits

A modern and accurate way to test for ovulation relies on detection of the LH surge with ovulation predictor kits. The sudden increase in circulating LH when there is a mature egg in the ovary triggers that egg to undergo the final maturational steps that allow it to become fertilized by sperm and also triggers the egg's release from the ovary. One advantage of the ovulation predictor kits is detection prior to ovulation. These kits become positive about a day prior to ovulation since the circulating LH must be metabolized, processed through the kidneys and excreted from the bladder in urine to allow for detection. The ovulation predictor kits are useful in timing intercourse or artificial inseminations with sperm.

5. Random luteal phase progesterone concentration

The luteal phase of the menstrual cycle is characterized by high circulating progesterone concentrations. The uterine endometrium undergoes structural changes in the presence of progesterone that can be seen histologically (under the microscope). Pathologists can date the endometrium with respect to the day of ovulation with good accuracy. Therefore, a luteal phase endometrial biopsy has been used to confirm ovulation. Also, a random serum progesterone concentration in the luteal phase may confirm ovulation. One disadvantage of the random serum progesterone concentration is that the level is pulsatile with large changes every 5-15 minutes, so that if you obtained 3 different serum levels on the same day you could receive three very different concentrations. Cutoffs for deciding that ovulation has occurred are controversial with a wide range of accepted values from about 4 ng/ml to 10 ng/ml.

Additional techniques

The other available methods of ovulation detection are considerably more involved and are rarely warranted in the clinical setting. The additional effort and expense of this testing can be significant and the additional information gained is usually not useful clinically. These additional techniques include

1. Serial ultrasonography,

Daily transvaginal sonograms look for the development and eventual collapse of an ovarian follicle. This is expensive, time consuming and not much more informative than the ovulation predictor kit. It is also not uncommon to "miss ovulation" since the follicle can collapse with the release of the egg and reaccumulate with fluid to form the corpus luteum cyst (which can look like a follicle) between ultrasounds.

2. Frequent blood sampling,

Blood can be sampled up to every few (usually 10-15) minutes for days looking for subtle changes in hormone values that reflect ovulation. This testing is the "gold standard" for ovulation detection but is usually only useful in research where the additional gathered information may change the research findings. Clinically, this level of precision is not needed.

3. Flushing the body for eggs or embryos,

This is restricted to experimental settings, where the pelvic cavity or the uterine cavity is flushed and the washings are examined microscopically for the presence of eggs or embryos. This can involve minor surgical procedures, there are serious ethical and moral concerns and the retrieved products are not usually viable.

source: http://www.drdaiter.com/

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