Adenomyosis: More common than you think

Transvaginal ultrasonography, needle biopsy, and MRI often can’t distinguish adenomyosis from fibroids. Classical signs like uterine enlargment, pelvic pain, and abnormal menstrual bleeding are not pathognomic.

With no clear-cut set of signs and symptoms to advertise its presence, experts suggest diagnosis may require MRI, transvaginal U/S, and/or needle biopsy. Among your treatment options: hysterectomy, GnRH agonists, and the levonorgestrel IUD.

A denomyosis, first described in 1860, is a common nonmalignant condition of the uterus characterized by the presence of endometrial glands and stroma ectopically located in the myometrium. How common is it?

The disease has been reported in 54% of uteri at necropsy. And because most studies have attempted to calculate its incidence from unsolicited hysterectomized specimens, we don’t really have an accurate estimate of how common the disease is in the general population. The reported incidence also varies widely depending on what definition is used to define the disease. The incidence is directly proportional to the number of histologic sections that are examined, and depends on how carefully the pathologist searches for it. One investigator, for instance, found that it occurred in 31% of hysterectomized specimens where three routine sections were performed, but increased to 61% with six sections. So it’s not surprising that the incidence of adenomyosis reported in the literature ranges from 8.8% to 61.5%.

Similarly, the exact pathogenesis of adenomyosis remains a mystery. Some researchers theorize that a disruption occurs in the basalis layer of the endometrium, allowing the glands and stroma to invade the myometrium. This causes hyperplasia and hypertrophy of the myometrium, enlarging the uterus. But how this disruption occurs remains unclear. Some suspect that surgical trauma triggers it. Prior uterine surgery—in particular dilation and curettage associated with spontaneous and induced abortion—increases the risk of adenomyosis. But this alone cannot explain adenomyosis because the disease is known to exist in women who have never undergone uterine surgery. High estrogen levels have also been implicated as the mechanism of myometrial invasion. We know, for instance, that parity has been linked to adenomyosis, and it may be directly related to the number of live births. Endometrial hyperplasia, an estrogen-dependent lesion, has also been linked to adenomyosis in some studies.

How do you make the diagnosis?

Traditionally a clinician will make the diagnosis retrospectively or it’s an incidental finding by the pathologist at the time of hysterectomy.

The standard diagnostic criterion is the finding of endometrial glands and stroma located more than one low-powered field (2.5 mm) from the basalis layer of the endometrium. However, this definition varies widely, with nine definitions seen in our literature search.

Although adenomyosis may cause uterine enlargement, the organ does not become massive. It usually weighs between 80 and 200 g, unless fibroids are also present. Upon gross evaluation the myometrial wall appears thickened and often contains small chocolate-colored areas, which represent islands of endometrial bleeding.

TWO VARIETIES OF ADENOMYOSIS have been described. The most common type, occurring in two thirds of cases, is a diffuse disease resulting in generalized enlargement of both anterior and posterior walls of the uterus. The second presentation, occurring in one third of the cases, is a focal disease. Often there are distinct unencapsulated areas of adenomyosis within the myometrium referred to as adenomyomas.

Although the disease is difficult to diagnose in vivo, a few radiographic techniques have been making some headway. Since patients suspected of having adenomyosis preoperatively might have other pathologies contributing to their symptoms, it is important to differentiate them from one another because treatment options can vary. Some co-existing conditions, such as dysfunctional uterine bleeding, may not require very aggressive treatment.

• A number of studies have proposed transvaginal ultrasonography (TVU), needle biopsies, and magnetic resonance imaging (MRI) to detect adenomyosis.

The problem with these measures is that they are far from perfect; sensitivities and specificities vary widely from study to study. And these diagnostic tools often cannot distinguish fibroids from adenomyosis, one of the main reasons for trying to establish a pretreatment diagnosis.

• Attempts have been made to diagnose the condition preoperatively by transcervical needle biopsy of the myometrium.

However, even with multiple needle biopsies, the test’s sensitivity (45%) is too low to be of practical clinical value. Other researchers have suggested that TVU may be used to diagnose adenomyosis. They suggest U/S may reveal irregular cystic spaces, heterogenic lesions, myometrial echoes with indistinct margins, mottled texture, and linear striations. A wide range of sensitivities have been reported (53%–70%). underscoring the limited value of this approach. Another disadvantage of TVU is that its accuracy in making the diagnosis depends on the operator and patient.

• An increasing number of clinicians are using MRI to detect adenomyosis and it appears to be the best way to make the diagnosis.

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