Management of Cystic Lesions on the Uterus
Critical Distinction: These Are Not Ovarian Cysts
The most important first step is to confirm whether these cysts are truly uterine in origin or are actually ovarian/adnexal masses being misidentified. True cystic lesions arising from the uterus itself are rare and include nabothian cysts (cervical), adenomyotic cysts (subserosal), and Müllerian cysts, which are frequently misdiagnosed as ovarian pathology on imaging 1, 2, 3.
Diagnostic Approach
Imaging Evaluation
- Transvaginal ultrasound combined with transabdominal ultrasound is the primary imaging modality to characterize these lesions and definitively identify whether both ovaries are normal and separate from the cystic structures 4, 5.
- The key diagnostic feature is demonstrating that normal ovaries are visualized separately from the cystic masses, which confirms a non-ovarian origin 6, 3.
- If ultrasound findings remain indeterminate after high-quality examination, MRI is the preferred problem-solving modality (not CT) for further characterization 7, 5.
Specific Uterine Cyst Types
Cervical Nabothian Cysts:
- These are the most common uterine cysts, typically small and asymptomatic in reproductive-age women 1.
- Large nabothian cysts (up to 4 cm) can mimic malignancy but are almost always benign 1.
- Ultrasound can reliably distinguish these from adenoma malignum (rare malignant cervical lesion) by demonstrating smooth walls, anechoic content, and lack of solid components 1.
Subserosal Adenomyotic Cysts:
- These present as multiple cystic structures on the uterine surface, typically in premenopausal women with abnormal uterine bleeding 2.
- Management options include hormonal therapy or surgical excision, with high recurrence rates requiring long-term imaging follow-up 2.
Müllerian Cysts (Endosalpingiosis):
- These pedunculated cystic masses arise from the uterine wall and are frequently misdiagnosed as ovarian cysts 3.
- Laparoscopic resection is curative once correctly identified 3.
Management Algorithm
If Cysts Are Confirmed as Uterine Origin:
For small cervical nabothian cysts (<3 cm): No intervention required; these are physiologic 1.
For large or symptomatic cervical cysts: Consider aspiration for debulking if causing mass effect, followed by histologic confirmation 1.
For subserosal adenomyotic cysts in reproductive-age women:
For suspected Müllerian cysts: Laparoscopic excision with histologic confirmation 3.
If Cysts Are Actually Ovarian/Adnexal (Common Misdiagnosis):
For premenopausal women:
- Simple cysts ≤5 cm: No management needed 7
- Simple cysts >5 cm but <10 cm: Follow-up ultrasound at 8-12 weeks during proliferative phase 7
- Complex cysts or cysts ≥10 cm: Gynecology referral 4, 7
For postmenopausal women:
- Simple cysts ≤3 cm: No management needed 7
- Simple cysts >3 cm but <10 cm: Annual follow-up for at least 1 year, consider surveillance up to 5 years if stable 7
- Any complex features: Gynecology or ultrasound specialist referral 7
Critical Pitfalls to Avoid
- Do not assume all pelvic cysts are ovarian—failure to identify normal ovaries separately leads to misdiagnosis and inappropriate management 6, 3.
- Do not perform fine-needle aspiration of solid or mixed masses—this is contraindicated due to risk of seeding if malignant 7.
- Do not operate prematurely on simple cysts <10 cm without observation—surgical complication rates are 2-15% for benign lesions 5.
- Do not use CT for characterization—MRI provides superior soft tissue detail for indeterminate pelvic masses 7, 5.
When to Refer
- Immediate gynecology referral: Any cyst with solid components, irregular walls, septations with vascularity, or rapid growth 4, 7.
- Gynecologic oncology consultation: O-RADS 4-5 lesions (≥10% malignancy risk) if ovarian origin is confirmed 4, 7.
- Ultrasound specialist or MRI: Indeterminate lesions after initial imaging, or when uterine versus ovarian origin cannot be determined 7, 5.