Measurement of progesterone in serum. Often measured to check the occurrence of prior ovulation. Used to infer the onset of ovulation in ovulation induction or assisted conception programs, and attaches extra significance to an apparently raised serum LH in judging the onset of the LH surge during monitoring. The result should be available within 4 hours for these purposes. Abbr. serum P4.

Menstrual cycles caused by ovarian activity (or ovarian cycles) not accompanied by ovulation. The serum progesterone stays low, whereas some development of tertiary follicles and production of estradiol takes place. See also anovulatory dysfunctional uterine bleeding.

Serial transvaginal ultrasounds of the ovary during the follicular phase to track the growth of one or more tertiary follicles, accompanied usually by serial estimations of serum estradiol, serum LH and serum progesterone, for the two-fold purpose of estimating follicular maturity (to time intercourse, a mid-cycle-dependent investigation such as a postcoital test, or an egg retrieval) and identifying the onset of the LH-surge, which can affect the timing of the intervention. Sometimes accompanied by injection of human chorionic gonadotropin to trigger ovulation at a precisely anticipated time.

(PCT) A test of: (1) receptiveness of the cervical mucus to sperm; and (2) sperm motility -- both of which are needed for the test to be a positive test. It's essential that the test be done to coincide with ovulation, tested with a urinary LH kit or measurements of serum estradiol (high), serum LH (preferably high) and serum progesterone (still low), because the job description of the cervical mucus at other times is to be impenetrable to sperm (i.e. the PCT will be negative for normal reasons).

Infertility for which no obvious cause has been found after the following tests have been done with normal results: a sperm count or postcoital test; a test of ovulation, such as a serum progesterone that is satisfactorily high; and a laparoscopy (used to show that the tubes are open and that there is no endometriosis or other obvious abnormality). Although a hysterosalpingogram (HSG) can substitute for laparoscopy in excluding blockage of the fallopian tubes, an HSG can miss peritubal adhesions and will miss endometriosis. Infertility should not be considered unexplained unless a thorough, careful laparoscopy has been done.