Adenomyosis may involve the uterus focally, creating an adenomyoma, or diffusely. With diffuse involvement, the uterus becomes bulky and heavier.
The cause of adenomyosis is unknown, although it has been associated with any sort of uterine trauma that may break the barrier between the endometrium and myometrium, such as a caesarean section, tubal ligation, pregnancy termination, and any pregnancy.
Some say that the reason adenomyosis is common in women between the ages of 35 and 50 is because it is between these ages that women have an excess of estrogen. Near the age of 35, women typically cease to create as much natural progesterone, which counters the effects of estrogen. After the age of 50, due to menopause, women do not create as much estrogen.
MRI provides better diagnostic capability due to the increased spatial and contrast resolution, and to not being limited by the presence of bowel gas or calcified uterine fibroids (as is ultrasound). In particular, MR is better able to differentiate adenomyosis from multiple small uterine fibroids. The uterus will have a thickened junctional zone with diminished signal on both T1 and T2 weighted sequences due to susceptibility effects of iron deposition due to chronic microhemorrhage. A thickness of the junctional zone greater than 10 to 12 mm (depending on who you read) is diagnostic of adenomyosis (<8 mm is normal). Interspersed within the thickened, hypointense signal of the junctional zone, one will often see foci of hyperintensity (brightness) on the T2 weighted scans representing small cystically dilatated glands or more acute sites of microhemorrhage.
MR can be used to classify adenomyosis based on the depth of penetration of the ectopic endometrium into the myometrium.
Those that believe an excess of estrogen is the cause or adenomyosis, or that it aggravates the symptoms, recommend avoiding products with xenoestrogens and/or recommend taking natural progesterone supplements.
In a younger woman, considerations should be broadened to include