# Adenomyosis: Diagnosis and Management

## Overview

Adenomyosis is defined by the presence of endometrial glands and stroma within the myometrium, accompanied by surrounding smooth muscle hypertrophy. Previously diagnosed only on hysterectomy specimens, it is now increasingly recognized through imaging. Prevalence is 20 to 35% in hysterectomy specimens and is likely higher with imaging-based diagnosis. Peak incidence is between 40 and 50 years of age, though it can affect younger women. Adenomyosis frequently coexists with endometriosis (40 to 60%), fibroids (35 to 55%), and endometrial polyps.

## Pathogenesis

The invagination theory proposes that endometrial basalis invades the myometrium through a disrupted endomyometrial junction. This disruption may result from prior uterine surgery (cesarean section, dilation and curettage, myomectomy), trauma, or chronic inflammation. The metaplasia theory suggests de novo differentiation of Mullerian remnants within the myometrium. Adenomyosis is both estrogen- and progesterone-dependent.

## Clinical Presentation

### Symptoms

Heavy menstrual bleeding is the most common symptom, occurring in 50 to 70% of patients. Dysmenorrhea occurs in 30 to 50% and is typically progressive, often beginning before the onset of menstrual flow. Chronic pelvic pain and dyspareunia are additional complaints. Bloating and pressure symptoms occur if the uterus is significantly enlarged. Up to one-third of patients may be asymptomatic.

### Physical Exam

The uterus is diffusely enlarged, globular, and "boggy," which contrasts with the irregular contour produced by fibroids. Uterine tenderness is common, especially during menses. It may be difficult to distinguish adenomyosis from fibroids on physical exam alone.

## Diagnosis

### Transvaginal Ultrasound (TVUS)

TVUS is the first-line imaging modality. Characteristic features include asymmetric myometrial thickening (comparing anterior to posterior wall), heterogeneous myometrial echotexture (described as a "Venetian blind" pattern), myometrial cysts (small anechoic spaces within the myometrium), subendometrial linear striations ("fan-shaped" shadowing), hyperechoic islands representing ectopic endometrial tissue, an irregular or indistinct endomyometrial junction, and a globular uterine contour. Sensitivity ranges from 72 to 89% and specificity from 65 to 98%. The exam is operator-dependent and requires experience in recognizing subtle features.

### MRI

MRI is superior to TVUS for diagnosis and surgical planning. The most specific finding is junctional zone thickening greater than 12 mm. A junctional zone greater than 8 mm with focally irregular borders is suggestive. A junctional zone to myometrial ratio greater than 40% also supports the diagnosis. On T2-weighted images, the junctional zone appears thickened and low-signal with high-signal foci representing ectopic endometrial glands. On T1-weighted images, high-signal hemorrhagic foci may be seen within the myometrium. MRI is useful for distinguishing adenomyosis from fibroids when TVUS is equivocal.

### Distinguishing Adenomyosis from Fibroids

Adenomyosis has ill-defined borders that blend into the myometrium, a diffuse or elliptical shape, fan-shaped shadowing from the subendometrial region, diffuse vascularity on Doppler, and a thickened junctional zone on MRI. Fibroids have a well-defined capsule, a round or oval mass shape, edge shadowing posteriorly, circumferential vascularity on Doppler, and a displaced but normal junctional zone on MRI.

| Feature | Adenomyosis | Fibroid |
|---|---|---|
| Borders | Ill-defined, blending into myometrium | Well-defined capsule |
| Shape | Diffuse or elliptical | Round or oval mass |
| Ultrasound shadowing | Fan-shaped from subendometrial region | Edge shadowing posteriorly |
| Doppler vascularity | Diffuse | Circumferential |
| MRI junctional zone | Thickened (>12 mm) | Displaced but normal |
| Surgical capsule | Absent | Present |

<image>Side-by-side TVUS and MRI images comparing adenomyosis and fibroids: TVUS showing heterogeneous myometrium with cystic spaces and fan-shaped shadowing (adenomyosis) versus a well-circumscribed hypoechoic mass with edge shadowing (fibroid); MRI showing thickened junctional zone greater than 12 mm with high-signal foci on T2 (adenomyosis) versus a well-delineated low-signal mass (fibroid)</image>

## Medical Management

### LNG-IUD (First-Line)

The levonorgestrel IUD is the most effective medical treatment for adenomyosis-related bleeding and pain, reducing menstrual blood loss by 70 to 90%. Its local progestin effect suppresses ectopic endometrial tissue. The device lasts 5 years and may be replaced for ongoing management. It may also reduce uterine volume over time.

### Combined Hormonal Contraceptives

Continuous use is preferred over cyclic use. These agents reduce dysmenorrhea and heavy menstrual bleeding but are less effective than the levonorgestrel IUD for adenomyosis.

### Progestin-Only Therapies

Norethindrone acetate at 5 mg daily is an effective option. Dienogest at 2 mg daily, though not available in the United States, is widely used in Europe and Asia and has been specifically studied for adenomyosis. Depot medroxyprogesterone acetate at 150 mg intramuscularly every 12 weeks is another alternative. These agents induce amenorrhea and reduce both pain and bleeding.

### GnRH Agonists

Leuprolide depot is effective for symptom control and uterine volume reduction. Add-back therapy is required for use beyond 6 months. It is useful as a preoperative treatment or as a bridge to menopause.

### GnRH Antagonists (Oral)

Elagolix and the relugolix combination tablet have emerging data for adenomyosis, having been studied primarily for fibroids and endometriosis. They may offer a long-term oral option with integrated add-back therapy.

### Non-Hormonal

NSAIDs provide relief for dysmenorrhea. Tranexamic acid reduces heavy menstrual bleeding. Iron supplementation addresses anemia.

## Surgical Management

### Hysterectomy

Hysterectomy is the definitive treatment for adenomyosis. It is indicated for refractory symptoms when fertility is not desired. It can be performed vaginally, laparoscopically, or via laparotomy depending on uterine size. Histologic examination of the specimen confirms the diagnosis.

### Conservative Surgical Options

Adenomyomectomy (excision of focal adenomyosis) is an option for women desiring fertility with focal disease (adenomyoma). It is technically challenging because there is no clear capsule, unlike fibroids. Evidence is limited, and recurrence is common. It requires an experienced surgeon and uterine wall reconstruction. Uterine artery embolization has some evidence for symptom improvement in adenomyosis but is less effective than for fibroids and is not recommended for women desiring fertility.

### MRI-Guided Focused Ultrasound

This is an emerging treatment with limited data for adenomyosis. It may reduce symptoms in select patients with focal disease.

## Adenomyosis and Fertility

The association between adenomyosis and infertility is increasingly recognized. Adenomyosis impairs endometrial receptivity and implantation, alters uterine contractility by disrupting peristalsis, and creates a chronic inflammatory environment. IVF outcomes in patients with adenomyosis show lower implantation rates and higher miscarriage rates in some studies. GnRH agonist pretreatment for 2 to 3 months before IVF may improve outcomes, though evidence is limited. Adenomyomectomy in select cases of focal disease is another option. More research is needed to establish optimal management for adenomyosis-related infertility.

<image>Treatment algorithm for adenomyosis organized by fertility desire: fertility desired (medical management with GnRH agonist pretreatment before IVF, adenomyomectomy for focal disease) versus fertility not desired (LNG-IUD first-line, then GnRH agonists or oral GnRH antagonists, then hysterectomy for refractory symptoms)</image>

## Clinical Pearls

Adenomyosis and fibroids frequently coexist. Do not assume all myometrial abnormalities are fibroids; look for adenomyosis features on ultrasound.

The levonorgestrel IUD is the most effective medical treatment for adenomyosis-related bleeding and should be tried before proceeding to surgery.

MRI is the best imaging modality for confirming adenomyosis and is essential when ultrasound is equivocal or surgical planning is needed.

Junctional zone thickening greater than 12 mm on MRI is the most specific diagnostic criterion.

Dienogest is widely used internationally for adenomyosis, though it is not available in the United States.

Adenomyosis is increasingly recognized as a contributor to infertility and poor IVF outcomes. Consider it in the workup of unexplained infertility.

Unlike fibroids, adenomyosis has no capsule, making conservative surgery technically difficult with high recurrence rates.

## References

- Chapron C et al. Diagnosing adenomyosis: an integrated clinical and imaging approach. Hum Reprod Update. 2020;26:392-411
- ACOG Practice Bulletin No. 128: Diagnosis of Abnormal Uterine Bleeding (2012, reaffirmed 2022)
- Pontis A et al. Adenomyosis: a systematic review of medical treatment. Gynecol Endocrinol. 2016;32:696-700
- Sheng J et al. The LNG-IUS for the treatment of adenomyosis: a meta-analysis. Eur J Obstet Gynecol Reprod Biol. 2009;146:1-6
- Vercellini P et al. Uterine adenomyosis and in vitro fertilization outcome. Hum Reprod. 2014;29:964-977
- Van den Bosch T et al. Terms, definitions, and measurements to describe sonographic features of myometrium and uterine masses (MUSA consensus). Ultrasound Obstet Gynecol. 2015;46:284-298