| Absence of a 0.5°F rise on measurement of basal body temperature |
| Low value (<2 ng/mL) of midluteal phase serum progesterone concentration |
| Lack of an LH surge on monitoring urinary LH excretion |
| Out of phase timed endometrial biopsy |
| Lack of a periovulatory follicle on serial transvaginal sonography |
