Ovulation prediction and detection.

The development of a single technique for the accurate prediction and determination of ovulation has not yet occurred. A technique which enables one to predict ovulation and signals the end of the ovums lifespan would be of great assistance to those practicing periodic abstinence or those only using contraception during the period of potential fertility. The only positive confirmation of ovulation comes through the detection of a pregnancy or by identifying the ovum in the female reproductive tract. There are 3 methods which up to now have been used to estimate the time of ovulation and probable fertile period: 1) biological 2) biochemical and 3) biophysical. However 3 methods have been developed and used as reference procedures for the evaluation of simpler techniques. 1) Ultrasonography provides good presumptive but not definitive evidence that ovulation has occurred. Results indicate that it is possible to determine the time limits during which ovulation occurs about 85% of spontaneous or induced ovarian cycles. 2) An increase in the amplitude of the pulses of luteinizing hormone (LH) released from the pituitary is a prerequisite of ovulation. 3) Urinary LH levels determined from early morning specimens indicate that ovulation occurred 20-44 hours after a defined rise in urinary LH concentration. A rise or peak in plasma or urinary LH may be used as a reference point for oogenesis luteinization and dividing the cycle into phases. In order to recover mature oocytes it is necessary to predict ovulation within 3 or 4 hours; changes in LH level have been used for this purpose. Attempts are now being made to improve existing methods and develop new ways to pinpoint the fertile period. At present there are 4 useful indices of the 1st fertile day in each menstrual cycle: 1) the shortest of the last 6 menstrual cycles minus 18; 2) the 1st day of cervical mucus detectable at the lips of the vulva; 3) the day of defined rise in estrone-3-glucuronide (E1-3-G) concentration; and 4) the day of a defined rise in the ratio of E1-3-G/Pd-3alpha-G. There are also indices for the last fertile day in a cycle.