An abnormal condition of the uterus in which glands from the endometrium grow into the muscle of the wall of the uterus (the myometrium), causing local or general enlargement of the uterus, pain with periods, and perhaps heavier periods. A localised area of adenomyosis is called an adenomyoma and can be hard to distinguish from a fibroid on transvaginal ultrasound, although an increase in the serum CA 125 antigen level can point to the correct diagnosis. Unlike a fibroid it is not easily removed at surgery, because it's not clearly separable from surrounding tissue. There's no satisfactory long term treatment for adenomyosis: hysterectomy may be chosen if symptoms are bad enough. GnRH-agonists give just temporary relief.

A benign "tumor" of the muscular wall of the uterus (the myometrium). More common with increasing age, but can occur in women in their twenties. Can be single or multiple, and can be located on the outside of the uterus (a subserous fibroid), within the wall of the uterus (an intramural fibroid), or protruding into the cavity of the uterus (a submucous fibroid. The closer it is (or they are) to the endometrial cavity, the more likely it is that a fibroid will disturb reproduction (either as miscarriages or sometimes as infertility) and disturb menstrual bleeding. Surgery for removal of a fibroid, or myoma, is called a myomectomy.

An operation to remove a myoma, or fibroid. A myomectomy for a submucous fibroid is often possible at hysteroscopy; a myomectomy for an intramural fibroid (located within the wall of the uterus), usually requires an open operation, or laparotomy; a myomectomy for a subserous fibroid can be possible at laparoscopy.

A fibroid (or myoma) that grows from the wall of the uterus inwards to distort the endometrial cavity. Can be a cause of menorrhagia (heavy periods), intermenstrual bleeding, premenstrual spotting, infertility and miscarriage.

A fibroid (or myoma) that grows from the outside surface of the uterus, into the cavity of the abdomen, or peritoneal cavity. The least likely of any sort of fibroid to affect reproduction, but can cause symptoms of pressure or pain should it twist or degenerate suddenly.