What is the most likely cause of abnormal uterine bleeding with blood clots and pain in a 45-year-old obese (Body Mass Index (BMI) 40 kg/m2) woman with a history of myomectomy and multiple surgical evacuations for incomplete miscarriage, presenting with a bulky and tender uterus?

Adenomyosis is the Most Likely Diagnosis

The clinical presentation of a 45-year-old woman with heavy menstrual bleeding, blood clots, severe dysmenorrhea unresponsive to simple analgesia, and a bulky tender uterus on examination—particularly with a history of prior uterine surgery—is most consistent with adenomyosis (Answer A). 1

Clinical Reasoning Algorithm

Key Diagnostic Features Pointing to Adenomyosis

• Age and demographics: Middle-aged women in their 40s are the classic demographic for adenomyosis 2
• Symptom triad: Heavy menstrual bleeding with clots, severe dysmenorrhea refractory to NSAIDs, and a bulky tender uterus form the hallmark presentation 1
• Physical examination findings: The bulky, tender uterus without discrete masses is characteristic of diffuse adenomyosis rather than focal fibroids 1
• Prior uterine trauma: History of multiple surgical evacuations and myomectomy increases adenomyosis risk through disruption of the endometrial-myometrial junction 2

Why Not the Other Options?

Uterine fibroids (Option C) would be less likely because:

• The patient already underwent myomectomy 12 years ago, and while recurrence occurs in up to 50% of cases 1, fibroids typically present as discrete palpable masses rather than diffuse uterine enlargement 1
• Fibroids cause a firm, irregularly enlarged uterus with palpable nodules, not the uniformly bulky tender uterus described 1
• Pain from fibroids is typically related to degeneration or torsion of pedunculated fibroids, not the cyclic dysmenorrhea pattern described 1

Endometriosis (Option B) is less consistent because:

• Endometriosis primarily causes dyspareunia, dyschezia, and chronic pelvic pain rather than heavy menstrual bleeding as the dominant symptom 1
• The examination would typically reveal adnexal masses, nodularity in the cul-de-sac, or fixed retroverted uterus—not an isolated bulky tender uterus 1
• No adnexal masses were found on examination, making endometriosis less likely 1

Endometrial cancer (Option D) is unlikely because:

• While obesity (BMI 40) is a significant risk factor for endometrial cancer 2, the patient has regular 30-day cycles, which argues against the irregular bleeding pattern typical of malignancy 2, 3
• Endometrial cancer typically presents with postmenopausal bleeding or irregular bleeding in premenopausal women, not regular heavy menses 2
• The tender bulky uterus is not characteristic of early endometrial cancer 2

Important Clinical Caveats

Coexistence of Conditions

Adenomyosis frequently coexists with uterine fibroids, affecting diagnostic accuracy 1, 2. The ACR Appropriateness Criteria specifically addresses "middle-aged women with menorrhagia" where imaging reveals both fibroids and diffuse adenomyosis 1. However, the clinical presentation here—with uniform uterine tenderness and no discrete masses—favors adenomyosis as the primary pathology 1.

Diagnostic Confirmation Required

While the clinical diagnosis strongly suggests adenomyosis, transvaginal ultrasound or MRI should be performed to confirm the diagnosis and exclude coexistent pathology 2, 4. MRI is superior for diagnosing adenomyosis with high sensitivity and specificity 1.

Obesity as a Confounding Factor

The patient's BMI of 40 kg/m² increases risk for both adenomyosis and endometrial pathology 2, 5. Endometrial sampling should be considered despite regular cycles, given the obesity and age over 45 years, to exclude endometrial hyperplasia or malignancy 2, 5.

Management Implications

If adenomyosis is confirmed, treatment options include 1, 2:

• Levonorgestrel-releasing IUD (52-mg) as first-line medical therapy, reducing menstrual blood loss by 71-95% 2
• Uterine artery embolization (UAE) achieves symptomatic relief in 65-88% of patients with adenomyosis, though recurrence rates at 2 years approach 40-50% 1
• Hysterectomy remains definitive treatment when medical management fails and fertility preservation is not desired 1, 2