Reference methods to predict or detect ovulation have evolved substantially during the past few decades. The potential use and limitations of such methods are reviewed. The use of transvaginal ultrasonography with color flow mapping to monitor periovulatory changes in the intrafollicular morphology and blood flow is described.
PIP: Reference methods for the prediction and detection of ovulation are identified and evaluated. The methods currently being developed or already available are based on 1) calendar calculations, 2) a specific rise in basal body temperature, 3) the presence and type of cervical mucus, 4) changes in the concentration of circulating hormones, 5) the immunoassay of urinary steroid glucuronides and luteinizing hormone, 6) changes in ovarian morphology, and 7) changes in intrafollicular blood flow. Some of these methods include an improved algorithm for the day of shift basal body temperature, an electronic thermometer, a special syringe for sampling cervicovaginal fluid, and a visual test for determining the activity of peroxidases. A histologic endpoint has been determined for changes in the concentrations of circulating hormones. Immunotubes are available for measuring urinary estrone glucuronide and pregnanediol--3 alpha--glucuronide, and an immunostick for determining urinary luteinizing hormone. The concentration of plasma hormones and the time of follicular rupture (ovulation) can be viewed with ultrasonography. In the periovulatory period, transvaginal ultrasonography with color flow mapping shows changes in intrafollicular morphology and blood flow and those changes are described. The requirements of the markers are 1) to determine whether ovulation occurred, 2) to reveal the day of which the oocyte was released, 3) the prediction of ovulation, and 4) to specify the limits of the fertile period, which may be the 4th day before ovulation to 2 days after ovum release. Information that is necessary before performance assessment includes 1) the type of test and reproductive process being monitored, 2) the purpose, 3) the age and menstrual status of the user, 4) the endpoints for evaluation, and 5) the number of method failures. Clinical usefulness requires prospective randomized trials. Signs and reasons for anovulation are being investigated. Retrospective analysis shows that motivated and informed women have a low NFP failure rate. For fully lactating women and those approaching menopause, research is in progress. False positive and false negative tests are to be expected at the present level of technology, particularly among subfertile women.