The date of the menstrual cycle can be estimated from the histologic appearance of the endometrium.
Proliferative Phase:
(1) features: pseudostratified epithelium with mitoses and no vacuoles
(2) early: glands straight
(3) mid: glands coiled and stromal edema
(4) late: glands coiled without subnuclear vacuoles in epithelium
Interval Phase (post-ovulatory day 1):
(1) features: uniform subnuclear vacuoles present in < 50% of cells
Early Secretory Phase:
(1) features: vacuolated endometrium
(2) post-ovulatory day (POD) 2: subnuclear vacuolization uniformly present ( > 50% of glands) with mitotic figures frequent
(3) post-ovulatory day (POD) 3: subnuclear vacuoles and nuclei uniformly aligned, with scattered mitotic figures
(4) post-ovulatory day (POD) 4: vacuoles assume luminal position with mitotic figures rare
(5) post-ovulatory day (POD) 5: vacuoles infrequent with secretion in lumen of gland
Mid-Secretory Phase:
(1) features: nonvacuolated endometrium with stromal edema
(2) post-ovulatory day (POD) 6: luminal secretion prominent
(3) post-ovulatory day (POD) 7: beginning of stromal edema
(4) post-ovulatory day (POD) 8: maximal stromal edema
Late-Secretory Phase:
(1) features: nonvacuolated endometrium with stromal precidualization but no stromal breakdown
(2) post-ovulatory day (POD) 9: spiral arteries first prominent
(3) post-ovulatory day (POD) 10: thick periarterial cuff of predecidua
(4) post-ovulatory day (POD) 11: islands of predecidua in superficial compactum
(5) post-ovulatory day (POD) 12: beginning coalescence of islands of predecidua
(6) post-ovulatory day (POD) 13: confluence of surface islands of predecidua, with prominent stromal granulocytes
(7) post-ovulatory day (POD) 14: extravasation of red cells in stroma, with prominent stromal granulocytes
Menstrual Phase:
(1) features: crumbling of the stroma, hemorrhage, intravascular fibrin thrombi, stromal granulocytes prominent
(2) late menstrual: regenerative changes prominent
Limitations:
• The secretory phase is usually reported as a 2 day range.
• Post-menopausal change can result in weakly proliferative or inactive endometrium.
• Glandular and stromal breakdown with the endometrium showing a proliferative phase can occur in estrogen breakthrough bleeding.
• Disordered proliferative phase endometrium can show a variation in gland luminal diameters.
• In hyperplasias and endometrial carcinomas more complex abnormalities of the endometrium occur.
Specialty: Obstetrics & Gynecology