How long should we follow simple ovarian cysts with pelvic ultrasonography?
CURRENT GUIDELINES ON REPEAT IMAGING
The American College of Radiology (ACR) has created a “Choosing Wisely” guideline to clarify when repeat imaging for ovarian cysts is indicated, to reduce both patient anxiety and healthcare costs.9 These guidelines highlight the distress women may experience from repeat testing due to concerns about cancer.
The guidelines also note that testing is often done during varying times of the menstrual cycle, thereby detecting new cysts, as opposed to monitoring previously detected cysts. Repeat ultrasonography may lead to surgical interventions that are not evidence-based, such as cystectomy or oophorectomy, in patients without radiologic features of malignancy or associated pelvic pain. And while ultrasonography is less expensive than other imaging tests, unnecessary imaging can mean additional costs to the patient, such as copayments, and possibly large payments for patients without insurance.
The American College of Obstetricians and Gynecologists (ACOG) and the ACR guidelines recommend against unnecessary repeat imaging for ovarian cysts.7,10 The ACOG Practice Bulletin on the Evaluation and Management of Adnexal Masses states, “Simple cysts up to 10 cm in diameter on transvaginal ultrasonography performed by experienced ultrasonographers are likely benign and may be safely monitored using repeat imaging without surgical intervention, even in postmenopausal patients.”7
The ideal frequency for repeat testing is yet to be determined. In postmenopausal women with a simple cyst smaller than 5 cm, ACOG guidelines recommend an interval of 4 to 6 months for initial repeat imaging. ACR guidelines recommend no follow-up imaging for simple cysts smaller than 5 cm detected by high-quality ultrasonography in asymptomatic women of reproductive age or for simple cysts smaller than 1 cm in postmenopausal women.10
THE CLINICAL BOTTOM LINE
Simple ovarian cysts can develop as part of the normal menstrual cycle, and although they are more common in premenopausal women, they have been detected in 1 out of 5 postmenopausal women.9 Simple ovarian cysts are typically not cancerous in women of any age. Therefore, most simple ovarian cysts in asymptomatic women either require no follow-up imaging or can be safely monitored with limited repeat ultrasonography for a defined length of time.
Our 54-year-old postmenopausal patient has a simple cyst smaller than 5 cm. Based on current guidelines, the CA-125 level should be measured, with subsequent calculation of the RMI. Assuming a normal CA-125 and RMI, she should be reassured that the risk of progression to malignancy is extremely low. Repeating ultrasonography 4 to 6 months after the initial imaging is warranted. At that time, if no change in cyst size or composition is detected, ultrasonography can be repeated at 1 year after initial detection. After that, assuming no changes of the cyst on repeat imaging, the patient does not require additional follow-up.
