Management of a 1.9mm Ovarian Cyst on Left Ovary
No follow-up is required for a 1.9mm simple ovarian cyst in the left ovary, as it is well below the size threshold that would warrant clinical concern or intervention. 1
Size Classification and Risk Assessment
The 1.9mm cyst falls into the category of very small ovarian cysts that are:
- Well below the 3cm threshold for mandatory follow-up
- Considered physiologic/functional in nature
- Associated with minimal to no risk of malignancy
According to the O-RADS US Risk Stratification and Management System, unilocular smooth cysts ≤3 cm have a 0% risk of malignancy based on extensive clinical data 1.
Management Recommendations Based on Size
For Premenopausal Women:
- Cysts ≤3 cm: No further management required 1, 2
- Cysts >3 cm to <5 cm: Optional follow-up in 8-12 weeks 2
- Cysts >5 cm to <10 cm: Follow-up ultrasound in 8-12 weeks (preferably during proliferative phase) 1
For Postmenopausal Women:
- Cysts ≤3 cm: Optional follow-up in 1 year 1
- Cysts >3 cm: Annual ultrasound follow-up for 5 years 2, 3
Clinical Context and Considerations
A 1.9mm cyst is extremely small and likely represents:
- A normal physiologic variation
- A developing follicle
- A resolving corpus luteum
The risk of malignancy for symptomatic ovarian cysts in premenopausal women is approximately 1:1,000, increasing to 3:1,000 at age 50 4. However, this risk applies to larger, symptomatic cysts, not microscopic 1.9mm findings.
Important Caveats
Size Verification: Confirm that the measurement is indeed 1.9mm (not 1.9cm), as 1.9mm is extremely small and might be a measurement or reporting error.
Symptoms: If the patient is experiencing symptoms despite the small cyst size, further evaluation may be warranted to identify other potential causes.
Morphology: If the cyst has complex features (septations, solid components, irregular walls), additional evaluation might be needed regardless of size 1.
Risk Factors: In patients with significant risk factors for ovarian cancer (family history, BRCA mutations), management may need to be individualized beyond standard size-based protocols 1.
Follow-up Recommendations
For a 1.9mm simple ovarian cyst:
- No scheduled follow-up imaging is necessary
- Patient can be reassured about the benign nature of this finding
- Routine gynecologic care can continue as scheduled
This approach is supported by the American College of Radiology's O-RADS system, which recommends no follow-up for simple cysts ≤3 cm in premenopausal women 1, 2.