Ovarian Cyst Without Ovary: A Diagnostic Clarification
Understanding the Clinical Scenario
An "ovarian cyst without ovary" is anatomically impossible—what is being described is likely an adnexal cyst in a location where the ovary is not visualized or has been previously removed, making this a paraovarian cyst, peritoneal inclusion cyst, or remnant ovarian tissue. 1
The management approach depends entirely on clarifying what structure is actually present and its imaging characteristics.
Diagnostic Clarification Required
Most Likely Diagnoses
- Paraovarian cyst: A cyst arising from the broad ligament or fallopian tube remnants, separate from ovarian tissue 1
- Peritoneal inclusion cyst: Fluid trapped by peritoneal adhesions, often seen after prior surgery or infection 1
- Ovarian remnant syndrome: Residual ovarian tissue after oophorectomy that can develop cysts 1
- Misidentification: The ovary may be present but not visualized due to technical factors 1
Critical First Step
Obtain high-quality transvaginal ultrasound with careful documentation of whether ovarian tissue is truly absent or simply not visualized. 1 If the ovary cannot be identified, document whether the patient has a history of oophorectomy.
Risk Stratification Using O-RADS Classification
Once the cyst is properly characterized, apply the O-RADS US risk stratification system regardless of whether it arises from ovarian or paraovarian tissue 1:
O-RADS 2 (Almost Certainly Benign, <1% malignancy risk)
Paraovarian cysts and peritoneal inclusion cysts are classified as classic benign lesions when they demonstrate typical features. 1
- Simple cysts <10 cm: Anechoic, smooth thin wall, no internal elements 1
- Classic benign descriptors: Smooth walls, no solid components, no papillary projections 1
Management for premenopausal women: No follow-up needed if <5 cm; follow-up ultrasound in 8-12 weeks if 5-10 cm 2
Management for postmenopausal women: Follow-up in 8-12 weeks if 3-5 cm; specialist referral or MRI if 5-10 cm 1, 2
O-RADS 3 or Higher (Increased Risk)
- Any cyst ≥10 cm requires gynecologic evaluation 1
- Irregular walls, septations, solid components, or papillary projections warrant specialist referral 1
- Color Doppler score ≥4 increases suspicion and requires gynecologic oncology consultation 1
Management Algorithm
For Benign-Appearing Adnexal Cysts (O-RADS 2)
Premenopausal patients:
Postmenopausal patients:
Long-term surveillance: Consider annual follow-up for up to 5 years if stable 2
For Suspicious Features (O-RADS 3-5)
Immediate gynecologic referral is mandatory for any cyst with concerning features, regardless of whether ovarian tissue is identified. 1
- Irregular inner walls or septations 1
- Solid components with vascularity 1
- Papillary projections 1
- Ascites or peritoneal nodules 1
Critical Pitfalls to Avoid
- Never perform fine-needle aspiration of adnexal masses, whether ovarian or paraovarian, due to risk of malignant cell dissemination 1
- Do not assume benignity based solely on absence of ovarian tissue—paraovarian and peritoneal cysts can rarely be malignant 1
- Avoid unnecessary surgery for simple cysts <10 cm with benign features, as malignancy risk is <1% even in postmenopausal women 1, 2
- Do not overlook the possibility of ovarian remnant syndrome in patients with prior oophorectomy who develop adnexal cysts 1
- Ensure adequate follow-up for cysts >5 cm, as larger lesions may be more challenging to evaluate completely 2
Special Considerations
In patients with prior bilateral oophorectomy, any adnexal cyst requires careful evaluation to exclude ovarian remnant syndrome or malignancy from other sources. 1 MRI may be helpful for further characterization in these cases. 1
The risk of acute complications (torsion, rupture) in benign-appearing adnexal cysts is approximately 0.2-0.4%, which supports conservative management in most cases. 2