A normal intrauterine pregnancy can be first seen on the scan three days after a missed menstrual period. In women who fall pregnant after fertility treatment such as ovarian stimulation the pregnancy can be seen 17 days after ovulation. In women who conceive after IVF the pregnancy can be seen 17 days after the day of oocyte collection. There are, however, small variations in the timing of conception and women who wish to confirm that their pregnancy is located within the uterus are advised to delay their attendance until a week after the missed period (or three weeks after conception) to avoid coming for the scan too early. This is particularly important in women with uterine abnormalities such as fibroids or adenomyosis, which make it harder to see the pregnancy and sometimes the diagnosis may be delayed for several days.