Hi pollyanna67

I am assuming your gynae is giving you continuous combined HRT (ie continuous oestrogen along with progestogen) precisely because you had endometriosis in the past.
Although most women who have had a hysterectomy do not need added progestogen, and can take oestrogen only, in your case the added progestogen in theory should be preventing any growth in endometrial tissue elsewhere in the body.
Continuous combined HRT works for post-menopausal women with a uterus, because the progestogen prevents the oestrogen causing a build up in womb lining.
I would expect the gynaecologist who recommended your treatment will also ensure you are monitored reguarly to ensure this doesn't happen (ie the build up of endometriosis - tissues elsewhere in the body?). I would suggest you contact your gyane again for reassurance that you will be checked regularly, if this hasn't yet been promised as part of your treatment?
Here is what it says on this site about endometriosis:
Endometriosis
There is a small risk of reactivation of endometriosis with HRT use and any recurrence of symptoms should be reported. If a hysterectomy has been performed for endometriosis, the choice of HRT use thereafter should be influenced by the extent of endometriosis at the time of the operation. Since hysterectomy often causes a premature menopause, it is often advised to take HRT until the average age of the menopause; 51 years. HRT after hysterectomy usually consists of estrogen only. However, in the presence of endometriosis, estrogen may cause stimulation of residual deposits and consideration should be given to using continuous combined (estrogen plus daily progestogen) therapy, or tibolone, though little research has been done on the effect of different types and duration of therapy. Medical treatment of endometriosis often involves ovarian suppression which, along with ovarian removal, may increase the risk of osteoporosis.
http://www.menopausematters.co.uk/atoz.php#GlossEHurdity x