Adenomyosis

Adenomyosis is defined as the presence of endometrial glands and stroma within the myometrium. The ectopic endometrial tissue may be diffusely or focally distributed within the myometrium. Focal adenomyosis surrounded by myometrial hypertrophy is called an adenomyoma¹. In rare cases one or more large cyst may appear (an adenomyotic cyst or cystic adenomyoma)².

N80.0 Endometriosis of uterus.

Mean age at diagnosis is 40 years, but adenomyosis does also occur in younger women³.

Adenomyosis is considered to originate from direct contact between the endometrium and the underlying myometrium, allowing the formation of ectopic endometrial glands and stroma⁴. Adenomyosis involving the external myometrium is thought to result from disruption of the serosa from outside the uterus by infiltrative pelvic endometriosis^5,6. Some cases may arise from Müllerian remnants within the myometrium.

The histologic diagnosis of adenomyosis is made by the presence of endometrial stroma and glands in the myometrium⁷. There is no consensus among pathologists on invasion depth and various histopathological definitions have been reported.

Because most women with adenomyosis are of child-bearing age and/or favor a uterus sparing treatment, the diagnosis is nowadays generally made by imaging (MRI or ultrasonography) without histological confirmation. Adenomyotic lesions are generally ill‐defined within the myometrium.

In medical imaging, there are direct and indirect findings suggesting adenomyosis.

Direct signs are features indicative of the presence of echogenic endometrial tissue within the less echogenic myometrium: infiltration of the junctional zone will give rise to subendometrial lines and buds, and further infiltration and expansion results in hyperechogenic islands in the myometrium. Because of the cyclical shedding of endometrium in woman with an ovarian cycle, endometrial tissue in het myometrium may result in collections of trapped blood within the myometrium; myometrial cysts. Those myometrial cysts are typically surrounded by an echogenic rim. The crossing of the junctional zone by endometrial tissue results in an irregular and/or interrupted endomyometrial junction or junctional zone. The visualization of the junctional zone is optimized using 3-dimensional ultrasonography^8,9. The presence of endometrial tissue and cysts, within the myometrium can cause “fan shaped shadowing”. The latter being sonographic artefacts of alternating acoustic enhancement behind the cysts filled with liquid and wall shadow caused by the ultrasound beam tangentially crossing the solid cyst wall. Myometrial hypertrophy surrounding an adenomyotic focus may also cause acoustic shadowing. On color/power Doppler imaging vessels are typically crossing an adenomyotic lesion (translesional vascularity), as opposed to circumferential vascularization around a fibroid. However, circumferential vascularity, often of lesser intensity, may also be present around an adenomyotic focus,

Indirect signs are due to an increase in volume of the uterine wall secondary to the presence of ectopic endometrial tissue within the myometrium: asymmetrical myometrial wall thickening (in case one myometrial wall is more affected) or a globular uterus (in case of a diffuse infiltration of fundal, anterior, posterior and lateral uterine walls).

In reporting on adenomyosis, following 7 items should be evaluated¹⁰:

1. Presence

The diagnosis of adenomyosis should be based on more than 1 feature. The report specifies what features are present.

2. Location

The location of the lesions in the anterior, posterior, lateral left, lateral right or fundal myometrium is recorded.

3. Focal or diffuse

An adenomyotic lesion is reported as focal if > 25% of the circumference of the lesion is surrounded by normal myometrium. If < 25% is surrounded by normal myometrium, this adenomyotic lesion is called diffuse. In case of doubt, the lesion is reported as diffuse. When focal adenomyosis is demarcated distinctly because it is surrounded by hypertrophic myometrium, the lesion is called an adenomyoma.

4. Cystic/non‐cystic

Adenomyosis is reported as cystic in the presence of measurable (≥ 2 mm) myometrial cysts. The content of an adenomyotic cyst is typically anechoic or of low‐level echogenicity, and the cyst is typically surrounded by an echogenic rim.

5. Uterine layer involvement

Adenomyosis may involve one or more of the myometrial layers: the inner myometrium (also called the subendometrial layer or junctional zone); the middle myometrium (between the vascular arcade and the junctional zone) and the outer myometrium (the subserosal layer, between the serosa and the vascular arcade).

6. Extent

The extent of the disease is the estimated proportion of the uterine corpus that is affected by adenomyosis and is reported as: mild (< 25% affected); moderate (25–50% affected); or severe (> 50% affected).

7. Size of lesion

The largest diameter of an adenomyosis lesion(s) is reported.

The clinical relevance of adenomyosis is under investigation¹¹. Different morphological types, seen on ultrasound examination may have different clinical significance with respect to symptomatology, fertility, obstetric outcome and therapeutic options.

The treatment of choice for adenomyosis is primarily hormonal (e.g. levonorgestrel intrauterine device; oral progestins). Because the diffuse infiltrative nature of most adenomyotic lesions, surgery may be difficult and hazardous¹². Selective embolization and High-intensity Focused Ultrasound (HIFU) and shave been proposed as alternative treatment options^13,14.

1. Van den Bosch T, Dueholm M, Leone FP, Valentin L, Rasmussen CK, Votino A, Van Schoubroeck D, Landolfo C, Installé AJ, Guerriero S, Exacoustos C, Gordts S, Benacerraf B, D'Hooghe T, De Moor B, Brölmann H, Goldstein S, Epstein E, Bourne T, Timmerman D. Terms, definitions and measurements to describe sonographic features of myometrium and uterine masses: a consensus opinion from the Morphological Uterus Sonographic Assessment (MUSA) group. Ultrasound Obstet Gynecol 2015;46:284-98.

2. Brosens I, Gordts S, Habiba M, Benagiano G. Uterine Cystic Adenomyosis: A Disease of Younger Women. J Pediatr Adolesc Gynecol 2015;28:420-6.

3. Naftalin J, Hoo W, Pateman K, Mavrelos D, Holland T, Jurkovic D. How common is adenomyosis? A prospective study of prevalence using transvaginal ultrasound in a gynaecology clinic. Hum Reprod 2012;27:3432-9.

4. Vannuccini S, Tosti C, Carmona F, Huang SJ, Chapron C, Guo SW, Petraglia F. Pathogenesis of adenomyosis: an update on molecular mechanisms. Reprod Biomed Online 2017;35:592-601.

5. Chapron C, Tosti C, Marcellin L, Bourdon M, Lafay-Pillet MC, Millischer AE, Streuli I, Borghese B, Petraglia F, Santulli P. Relationship between the magnetic resonance imaging appearance of adenomyosis and endometriosis phenotypes. Hum Reprod 2017;32:1393-1401.

6. Kishi Y, Suginami H, Kuramori R, Yabuta M, Suginami R, Taniguchi F. Four subtypes of adenomyosis assessed by magnetic resonance imaging and their specification. Am J Obstet Gynecol 2012;207:114.e1-7.

7. Vandermeulen L, Cornelis A, Kjaergaard Rasmussen C, Timmerman D, Van den Bosch T. Guiding histological assessment of uterine lesions using 3D in vitro ultrasonography and stereotaxis. Facts Views Vis Obgyn 2017;9:77-84.

8. Exacoustos C, Brienza L, Di Giovanni A, Szabolcs B, Romanini ME, Zupi E, Arduini D. Adenomyosis: three-dimensional sonographic findings of the junctional zone and correlation with histology. Ultrasound Obstet Gynecol 2011;37:471-9.

9. Votino A, Van den Bosch T, Installé AJ, Van Schoubroeck D, Kaijser J, Kacem Y, De Moor B, Van Pachterbeke C, Timmerman D. Optimizing the ultrasound visualization of the endometrial-myometrial junction (EMJ). Facts Views Vis Obgyn 2015;7:60-3.

10. Van den Bosch T, de Bruijn AM, de Leeuw RA, Dueholm M, Exacoustos C, Valentin L, Bourne T, Timmerman D, Huirne JAF. A sonographic classification and reporting system for diagnosing adenomyosis. Ultrasound Obstet Gynecol 2019;53:576-582.

11. Naftalin J, Hoo W, Nunes N, Holland T, Mavrelos D, Jurkovic D. Association between ultrasound features of adenomyosis and severity of menstrual pain. Ultrasound Obstet Gynecol 2016;47:779-83.

12. Mikos T, Lioupis M, Anthoulakis C, Grimbizis GF. The outcome of fertility sparing and non-fertility sparing surgery for the treatment of adenomyosis. A systematic review and meta-analysis. J Minim Invasive Gynecol 2019 Aug 6. pii: S1553-4650(19)30337-1. 

13. de Bruijn AM, Smink M, Lohle PNM, Huirne JAF, Twisk JWR, Wong C, Schoonmade L, Hehenkamp WJK. Uterine Artery Embolization for the Treatment of Adenomyosis: A Systematic Review and Meta-Analysis. J Vasc Interv Radiol 2017;28:1629-1642.e1.

14. Marques ALS, Andres MP, Kho RM, Abrão MS. Is High-intensity Focused Ultrasound Effective for the Treatment of Adenomyosis? A Systematic Review and Meta-analysis. J Minim Invasive Gynecol 2020;27:332-343.

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