IS THE TIMING OF WITHDRAWAL BLEEDING A GUIDE TO ENDOMETRIAL SAFETY DURING SEQUENTIAL ESTROGEN-PROGESTAGEN REPLACEMENT THERAPY

Current regimens of sequential hormone replacement therapy are based o n data that show a protective effect on the endometrium of at least 10 days of progestagen. In clinical practice, onset of bleeding on or af ter day 11 of the progestagen phase is taken as reassurance of a norma l endometrium. 413 postmenopausal women taking oestrogen-progestagen h ormone replacement thera py with 10 or 12 days of progestagen per cycl e completed bleeding diaries for 3 months before endometrial biopsy. F or most women, bleeding started around the 13th day after starting pro gestagen. There was no correlation between endometrial histology and t iming of onset of bleeding. 11 (2.7%) women had complex endometrial hy perplasia. The presence of hyperplasia was 2.4% with onset of bleeding after 10 days of progestagen and 2.8% after 12 days. The timing of on set of withdrawal bleeding during oestrogen-progestagen HRT does not p redict endometrial hyperplasia.