The commonest site of endometriosis
Endometriosis

Endometriosis (ectopic endometrium) is the term used to describe the presence of endometrium (endometrial glands or stroma) in abnormal locations outside the uterus.
It occurs in following sites, in decreasing order of frequency -

1. Ovary                       2. Uterine ligaments           3. Rectovaginal septum                     4. Pelvic peritoneum
5. Laprotomy scar       6. Umbilicus, vagina, vulva or appendix.

Adenomyosis is the presence of endometrial tissue in the uterine wall, i.e., in the myometrium.
Vagina
Ovary
Urinary bladder
Peritoneal cavity