Approach Considerations
Although adenomyosis was first characterized in the 1800s, [11] the diagnostic criteria have differed among pathologists, and prevalence continues to be debated as higher-level imaging modalities have become more common. There is a need for agreed-upon, widespread diagnostic criteria to better understand the incidence and prevalence of adenomyosis.
Currently, adenomyosis remains a largely clinical diagnosis. Definitive diagnosis of adenomyosis requires a histologic examination of uterine tissue. [24] Typically this step is circumvented in women desiring future fertility or who wish to preserve their uterus. Increasing availability and technological advances in imaging such as ultrasound, CT, and MRI scans have improved evaluation for adenomyosis, but it still remains largely under-diagnosed until the time of hysterectomy. It is important both to maintain a high clinical suspicion for adenomyosis throughout the evaluation, as it may shape management options moving forward.
Laboratory Studies
On initial evaluation, laboratory workup should be the same as for any patient who presents for abnormal uterine bleeding. Pregnancy should be ruled out. Patients should be evaluated for anemia, thyroid and/or pituitary dysfunction, bleeding disorders (when indicated), as well as sexually transmitted infections. [25]
Imaging Studies
Advancement in imaging technology has significantly changed the presumptive diagnosis of adenomyosis. Ultrasound is the most common imaging modality used to evaluate gynecologic symptoms, with a sensitivity between 75% and 88% and a specificity from 67-93%. [22, 26, 27] Unfortunately, accuracy and sensitivity of ultrasound is variable depending on the training of the sonographer. As MRI has become more widely available, it has been reported to be the most reliable diagnostic method for diagnosing adenomyosis, with a reported sensitivity between 70% and 100% and a specificity of 86-93%. [26, 28, 29] However, ultrasonography is often preferred because it is more widely available and significantly more cost-effective for patients.
Ultrasonography
On transvaginal ultrasonography, common features include the following:
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Diffusely enlarged, globular, asymmetric uterus [27]
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Presence of myometrial cysts: poorly defined areas with abnormal echotexture
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Diffuse or focal thickening of the uterine junctional zone [31]
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Myometrial mass with ill-defined borders [31]
Ultrasound of an adenomyoma dissecting through the anterior uterine wall separate from the endometrial cavity.
Ultrasound features of adenomyosis have been categorized as direct (ie, those that indicate ectopic endometrial tissue in the myometrium) or indirect (ie, those that reflect changes in the myometrium secondary to endometrial tissue in the myometrium). A European consensus on definitions of these features classified myometrial cysts, hyperechogenic islands, and echogenic subendometrial lines and buds as direct features of adenomyosis, and globular uterus, asymmetric myometrial thickening, fan-shaped shadowing, translesional vascularity, irregular junctional zone, and interrupted junctional zone as indirect features. [32]
MRI
On T2-weighted MRI, the junctional zone is more easily visualized as a low signal intensity zone adjacent to the endometrium. Although exact diagnostic criteria vary, a junctional zone thickness greater than 12mm is generally considered diagnostic for adenomyosis, with a sensitivity of 63% and specificity of 96%, based on studies correlating junctional zone measurement on MRI and histologic confirmation of adenomyosis. [33] Additionally, heterotopic endometrial tissue appears as small foci of increased high signal intensity within the junctional zone. [26]
Procedures
Other procedures, such as diagnostic hysteroscopy, myometrial biopsy, and endometrial biopsy, have occasionally been found to be useful in identifying suspected adenomyosis.
Although hysteroscopy cannot definitively prove or exclude the presence of adenomyosis due to its limited visualization, examination and biopsy of the endometrial surface can demonstrate features which would support adenomyosis. These may include the following [34, 35] :
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Irregular endometrium with superficial openings
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Irregular subendometrial myometrium (junctional zone) on histologic exam
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Irregular myometrial architecture on histologic exam
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Intramural endometriomas
Myometrial biopsy has long been considered as a possible means for obtaining a specimen for histologic diagnosis without requiring hysterectomy. Myometrial core needle biopsy can be performed under direct visualization during diagnostic laparoscopy for the evaluation for chronic pelvic pain or infertility. [36, 37] Core needle biopsy obtained under direct visualization from an area that has been evaluated with ultrasound and suspected to have adenomyosis, has a sensitivity of 98% and a specificity of 100%. [37]
Some physicians have performed transvaginal myometrial core needle biopsy under ultrasound guidance, which is less invasive but requires physician training. Additionally, there is currently no protocol on the number of needle biopsies required. Uterine tissue specimen for histologic analysis may also be obtained via transcervical punch biopsy. [29]
Histologic Findings
The definitive diagnosis of adenomyosis depends on histologic examination identifying endometrial glands remote from the endomyometrial junction. Traditionally, diagnosis is made when endometrial glands and stroma are found at least 1 low-power field beneath the endomyometrial junction (greater than or equal to 4 mm). [24] However, looser diagnostic criteria have been proposed and adopted. Some pathologists have accepted a distance of greater than or equal to 2.5 mm between endomyometrial junction and ectopic endometrial glands acceptable for diagnosis. Further, other pathologists have suggested diagnosing adenomyosis only if a certain percentage of myometrium is involved. [24, 5]
On gross examination, adenomyotic uteri typically appear as diffusely enlarged and globular. Adenomyotic foci are surrounded by disordered, hypertrophied smooth muscle cells, sometimes containing hemolyzed blood and hemosiderin pigments. [5] Adenomyotic glands and stroma typically resemble proliferative endometrium, but occasionally may have secretory appearance. [2]
Occasionally, adenomyosis is present as a focal collection of endometrial glands and stroma within the myometrium remote from the endomyometrial junction, and this is termed adenomyoma. Adenomyomas are distinct from leiomyoma because of their poorly defined margins, which subtly merge with surrounding myometrium. In contrast, leiomyoma have discrete borders that can be easily separated from adjacent myometrium and enucleated at the time of myomectomy. [5]
Staging
Adenomyosis can be classified according to degree of endometrial penetration. Some experts suggest numeric grading—grades 1, 2 and 3, respectively—to adenomyotic involvement of the inner third, two thirds and entire myometrium. [38] Other clinicians suggest using the term “mild” to describe when only microscopic foci are present, or when only the inner third of myometrium is involved; severe or diffuse disease is diagnosed when disease extended to the outer two thirds of myometrium or there was involvement of the entire uterus. [39]
A universal grading system should be utilized to avoid over- and under-diagnosis of adenomyosis, and to provide better understanding of prevalence and response to treatment.
Histologic description of adenomyosis should include four parameters [10] :
Presence of ectopic endometrial tissue >2.5mm from endomyometrial junction
Depth of penetration within the myometrium
One third- mild
Between ⅓ and ⅔- moderate
More than ⅔- severe
Degree of spread (number of foci per low-power field)
1-3 islets - Grade 1
4-10 islets- Grade 2
>10 islets- Grade 3
Configuration of lesions
Diffuse
Nodular
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MRI of fundal adenomyoma.
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Photo of an adenomyoma dissecting through the uterine wall.
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Ultrasound of an adenomyoma dissecting through the anterior uterine wall separate from the endometrial cavity.
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Adenomyosis noted within thickened myometrium.
