Adenomyosis is the condition of an ingrowth in the endometrium, both glandular & stromal components, directly into the myometrium.
Causes: The cause of such ingrowth is not known. It may be related to repeated childbirths, vigorous curettage or excess of estrogen effect. Pelvic endometriosis co-exists in about 40 percent.
Pathogenesis: Histologically, it is characterized by the extension of endometrial glands and stroma beneath the endometrial—myometrial interface (EMI). As the submucosa is absent, endometrial glands lie in direct contact with the underlying myometrium. It forms nests, deep within myometrium. Subsequently, threre is myometrial hyperplasia around the endometriotic foci. Myometrial zone anatomy was observed by MRI. A junctional zone (with low signal intensity on T2 weighted images) is defined at the innermost layer of myometrium. It is thought that the disturbance of normal junctional zone (JZ) predisposes to secondary infiltration of endometrial glands and stroma to inner myometrial zone. The disturbance of junctional zone (JZ) may be due to the endometrial factors, genetic predisposition or altered immune response. Trauma to the deeper endometrium (repeated curettage), causing breakdown of EMI is also taken as an important etiologic factor.
Pathology: The growth and tissue reaction in the endometrium depend on the response of the ectopic endometrial tissues to the ovarian steroids. If the basal layer is only present, the tissue reaction is much less, as it is unresponsive to hormones. But, if the functional zone is present which is responsive to hormones, the tissue reaction surrounding the endometrium is marked. There is hyperplasia of the myometrium producing diffuse enlargement of the uterus, sometimes symmetrically but at times, more on the posterior wall. The growth may be localized or may invade a polyp (adenomyomatous).
Naked eye appearance: There is diffuse symmetrical enlargement of the uterus; the posterior wall is often more thickened than the anterior one. The size usually does not increase more than a large orange (12–14 weeks pregnant uterus). On cut section, there is thickening of the uterine wall. The cut surface presents characteristic trabeculated appearances.
Unlike fibroid, there is no capsule surrounding the growth. There may be visible blood spots at places
In about one-third, it remains asymptomatic being discovered on histological examination. The patients are usually parous with age usually above 40.
Menorrhagia (70%)—The excessive bleeding is due to increased uterine cavity, associated endometrial hyperplasia and inadequate uterine contraction. During normal menstruation, there are antegrade propagation of subendometrial contractions from the fundus to the cervix. In adenomyosis with distorsion of junctional zone myometrial contractions are abnormal and inadequate (see below).
Dysmenorrhea (30%)—Progressively increased colicky pain during period is due to retrograde pattern of uterine contractions. It also depends on the number and depth of adenomyotic foci in the myometrium. When the depth of penetration is > 80% of the myometrium, the pain is severe. Other causes of pain are—local tissue edema and prostaglandins.
Dyspareunia or frequency of urination—are due to enlarged and tender uterus.
Infertility: Women with adenomyosis have a higher incidence of infertility and miscarriage.