A 44-year-old multiparous woman with progressive dysmenorrhoea, heavy menstrual bleeding, and chronic pelvic pain undergoes total abdominal hysterectomy. The bisected uterine specimen is shown. The structure marked **A** represents the diffuse globular thickening of the posterior myometrium. Which of the following pathophysiological mechanisms BEST explains the clinical presentation in this patient?

Question

Accepted Answer

A. Increased myometrial contractility and junctional zone dysfunction leading to impaired placentation and abnormal uterine peristalsis. ## Why "Increased myometrial contractility and junctional zone dysfunction leading to impaired placentation and abnormal uterine peristalsis" is right

The diffuse globular thickening of the posterior myometrium marked as **A** is the hallmark gross finding of adenomyosis. This represents ectopic endometrial glands and stroma invading the myometrium (>2.5 mm below the endomyometrial junction), which disrupts normal junctional zone architecture. This disruption causes increased myometrial contractility, abnormal peristalsis, and junctional zone dysfunction. These pathophysiological changes directly explain the patient's clinical triad: dysmenorrhoea (from abnormal contractions), heavy menstrual bleeding (from impaired hemostasis and increased vascularity), and chronic pelvic pain (from myometrial ischemia and inflammation). The thickened junctional zone (16 mm on MRI) with characteristic linear striations and small myometrial cysts are diagnostic features of diffuse adenomyosis, as confirmed by histopathology. (Berek and Novak's Gynecology, 16th Edition, Chapter on Benign Diseases of the Female Reproductive Tract)

## Why each distractor is wrong

- **Benign smooth muscle proliferation with formation of well-circumscribed nodules**: This describes uterine leiomyomas (fibroids), not adenomyosis. The specimen explicitly shows absence of well-circumscribed myometrial leiomyomas (structure **D**). Fibroids typically present with mass effect rather than the diffuse thickening seen here.

- **Focal adenomyoma with polypoid intraluminal growth**: Focal adenomyomas are localized lesions, whereas this patient has diffuse adenomyosis with symmetric posterior myometrial thickening. Additionally, the endometrial cavity is preserved without polypoid intraluminal masses (structure **C**), ruling out this mechanism.

- **Uterine leiomyomatosis with secondary degeneration and cystic change**: While cystic spaces are present in the trabeculated cut surface (**B**), these represent small myometrial cysts characteristic of adenomyosis, not degenerating fibroids. The absence of well-circumscribed leiomyomas excludes this diagnosis.

**High-Yield:** Diffuse adenomyosis presents with a uniformly enlarged, globular uterus with thickened junctional zone (>12 mm) and causes dysmenorrhoea, menorrhagia, and chronic pelvic pain through myometrial infiltration and junctional zone dysfunction—not through mass effect like fibroids.

[cite: Berek and Novak's Gynecology, 16th Edition, Chapter on Benign Diseases of the Female Reproductive Tract]

Answer

B. Uterine leiomyomatosis with secondary degeneration and cystic change within the myometrial wall

Answer

C. Focal adenomyoma with polypoid intraluminal growth causing mechanical obstruction of menstrual outflow

Answer

D. Benign smooth muscle proliferation with formation of well-circumscribed nodules causing mass effect on the endometrial cavity

Explanation

Why "Increased myometrial contractility and junctional zone dysfunction leading to impaired placentation and abnormal uterine peristalsis" is right

Why each distractor is wrong

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