The vaginal smear test for estrus; it demonstrates the histological changes occurring in the vagina during the menstrual cycle.

The first cytopathology test, smear diagnosis of carcinoma of the cervix: the "Pap" test. Papanicolaou first reported in 1928 that he could recognize cancer cells (Proc. Third Race Betterment Conf., p. 528) but the importance of his findings was not generally accepted and he abandoned the work for some years.

"In 1943, after a three-year period of concentrated collaborative experience with the vaginal smear for the diagnosis of gynecologic cancer, Papanicolaou and Traut published their widely heralded monograph, Diagnosis of Uterine Cancer by the Vaginal Smear.... This report encompassed a variety of physiologic and pathologic states, including the menstrual cycle, puerperium, abortion, ectopic pregnancy, prepuberty, menopause, amenorrhea, endometrial hyperplasia, vaginal and cervical infections, and 179 cases of uterine cancer, 127 cervical and 52 corporeal" (Speert, Obstetric & gynecologic milestones, p. 289).

(Thanks to Juan Weiss for this reference and its interpretation.)