Screening for Ovulation

INDICATION

To confirm ovulation in a woman WITH PERIODS presenting with infertility.

BACKGROUND

1. LH and FSH rise for approximately 48 hours ("surge") at the onset of the ovulatory phase of the menstrual cycle.
2. Progesterone production rises in the ovulatory phase to a maximum during the luteal phase.
3. Basal body temperature rises by >0.5ºC during the ovulatory phase peaking about 8 days after the LH surge.

PREPARATION

Confirm menstruation. Exclude other causes of infertility including hyperprolactinaemia, chromosomal problems, and thyroid dysfunction.

METHOD

1. Arrange for blood to be taken on days 18, 21 and 24 for progesterone. Should be undertaken for at least 2 cycles.
2. A more intensive screening regimen is undertaken in the IVF clinic, and referral is an alternative option.
3. Blood for progesterone is taken in red top Vacutainers and may be posted to the lab.

INTERPRETATION

Progesterone >30 nmol/l between days 18 and 24 indicates an adequate luteal phase (production of progesterone by granulosa cell).
Evidence of ovulation and adequate luteal phase should prompt further investigation of causes of infertility unrelated to ovulation or menstrual cycle (husband's sperm count, tube problems etc.). A postcoital test should be considered if there is no evidence for any of these.
If there is no evidence of ovulation: review screening tests for other systemic causes of infertility or consider clomiphene test.

REFERENCE

Sverdloff R.S. et al., Endo. Metab. Clin. N. Amer. 17, 301-332 (1988).