What is the best course of action for a 14-year-old girl with a 1-month history of menstruation, a negative urine pregnancy test (UPT), and an ultrasound showing a cyst on her right ovary?

Management of Ovarian Cyst in a 14-Year-Old Girl

In a 14-year-old premenopausal girl with a right ovarian cyst and negative pregnancy test, the cyst is almost certainly physiologic and requires only conservative management with observation—no intervention is needed unless the cyst is >5 cm, in which case follow-up ultrasound at 8-12 weeks is indicated. 1

Initial Assessment and Risk Stratification

The first critical step is determining the cyst's size and sonographic characteristics on ultrasound:

• Simple cysts ≤3 cm are considered physiologic and require no additional management in premenopausal women 1
• Simple cysts >3 cm but ≤5 cm require no further management in premenopausal women 1
• Simple cysts >5 cm but <10 cm should be followed up in 8-12 weeks to confirm functional nature or assess for cyst wall abnormalities 1

The ultrasound report should specify whether this is a simple cyst (completely anechoic fluid, thin smooth walls, no septations, no solid components, no vascularity) or a complex cyst (containing septations, solid components, wall irregularity, or vascularity). 2, 1

Understanding Physiologic Cysts in Adolescents

Most ovarian cysts in premenopausal women—including adolescents—are functional in nature and resolve spontaneously. 2 The evidence is particularly reassuring in this age group:

• 98.7% of simple cysts in premenopausal women are benign 2
• The risk of malignancy in unilocular cysts in premenopausal women is only 0.5-0.6% 1
• In one large study, no simple cysts were diagnosed as cancer in women under 50 years among 12,957 cysts 1

Even hemorrhagic cysts (which may appear complex on ultrasound with retracting clot and peripheral vascularity) are typically functional and benign in premenopausal women, and they decrease or resolve on follow-up at 8-12 weeks. 2, 1

Management Algorithm Based on Cyst Characteristics

If Simple Cyst ≤5 cm:

• No follow-up imaging needed 1
• Reassure the patient and family that this is a normal physiologic finding
• Counsel about menstrual cycle-related symptoms that may occur

If Simple Cyst >5 cm but <10 cm:

• Schedule follow-up ultrasound at 8-12 weeks, preferably during the proliferative phase of the menstrual cycle 1
• During follow-up, assess for resolution, decrease in size, or any development of solid components, septations, wall irregularities, or new vascularity 1
• Most functional cysts will resolve spontaneously by this time 2

If Cyst ≥10 cm:

• Surgical management is indicated regardless of other features, as cysts this size automatically elevate to at least O-RADS 3 category with increased malignancy risk 3
• Refer to gynecology for evaluation and management

If Complex Features Present:

Determine the specific type of complex cyst:

• Hemorrhagic cyst ≤5 cm: No further management needed in premenopausal women 1
• Dermoid cyst or endometrioma: Optional initial follow-up at 8-12 weeks, then yearly surveillance if stable 1
• Other complex features (multiple septations, solid components, papillary projections): Refer to gynecology for further evaluation 2, 1

Critical Pitfalls to Avoid

Do not operate prematurely on simple cysts <10 cm without appropriate observation period. The risk of malignancy is extraordinarily low, and most will resolve spontaneously. 1 Unnecessary surgery exposes the patient to operative risks and potential loss of ovarian tissue, which can impact future fertility.

Do not assume persistent cysts are pathological. Many benign neoplasms can be safely followed, with risk of malignancy in classic benign-appearing lesions managed conservatively being <1%, and acute complications (torsion, rupture) occurring in only 0.2-0.4%. 1

Do not order tumor markers like CA-125 in adolescents with simple cysts. These are not indicated for benign-appearing functional cysts in premenopausal women and can lead to unnecessary anxiety and interventions. 1

When to Seek Urgent Evaluation

While conservative management is appropriate for most cases, the patient should return immediately if she develops:

• Severe acute abdominal pain (concerning for ovarian torsion or rupture) 4
• Hemodynamic instability (concerning for hemorrhage) 4
• Fever with abdominal pain (concerning for infection)

Suspected adnexal torsion requires early laparoscopy and de-torsion. 4 However, only 3% of cysts undergo torsion, and acute intervention during observation is rarely needed. 5

Patient and Family Counseling

Explain that ovarian cysts are extremely common in menstruating girls and women, with about 7% of women having an ovarian cyst at some point in their lives. 6 The vast majority are physiologic, related to normal ovarian function, and resolve without treatment. The negative pregnancy test confirms this is not an ectopic pregnancy or pregnancy-related complication. 3