Ovarian pregnancies usually are diagnosed by the trophoblast which has gone into the ovarian tissue being found histologically. These pregnancies usually suggest haemorrhage from the corpus luteum or a rupture of ovarian cysts. The average age at which they appear is 29, just as it is the age for tubal pregnancies, but they do differ because there are few signs of infection and of infertility, and there are more multipara and women who are wearing an IUD. Two-thirds of ovarian pregnancies are on the peritoneal surface or in the hilum, away from the corpus luteum, and one-third are situated on the scar of the follicular ostium and have later infiltrated into the follicle. Most of these cases can be explained by reflux of the oocyte into the peritoneum.