Ovarian Cysts for USMLE Step 2
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Ovarian Cysts for the USMLE Step 2 Exam
- Definition:
- Ovarian cysts are fluid-filled sacs on or within an ovary. Most are benign and categorized as either functional (related to the menstrual cycle) or pathologic, with functional cysts being most common in reproductive-aged women.
- Types of Ovarian Cysts:
Functional Cysts
- Related to normal ovulation and usually resolve spontaneously.
- Result from a follicle that fails to rupture and release an egg.
- Typically asymptomatic and self-resolving within one to three menstrual cycles.
- Form when the corpus luteum fails to degenerate and instead fills with fluid or blood.
- Can cause pelvic pain and menstrual irregularities but often resolve on their own.
- Associated with elevated human chorionic gonadotropin (hCG) levels, such as in pregnancy or fertility treatments.
- Generally resolve once hCG levels decrease.
Pathologic Cysts
Caused by abnormal growth, they may be benign or malignant and often require further evaluation.
Dermoid Cysts (Mature Cystic Teratomas):
- Arise from germ cells and may contain multiple tissue types (e.g., hair, skin, teeth).
- Often asymptomatic but can cause pain if they undergo torsion or grow large.
- Also called “chocolate cysts” due to the accumulation of thick, dark blood, these arise from endometriosis.
- Associated with chronic pelvic pain, dysmenorrhea, and infertility.
- Benign epithelial tumors, which can be serous (thin fluid) or mucinous (thicker, gelatinous fluid).
- May grow large and cause abdominal discomfort or distension.
Clinical Presentation
- Symptoms:
- Many ovarian cysts are asymptomatic, discovered incidentally. Symptomatic cysts can cause:
- Pelvic Pain: May be mild or severe, especially if the cyst is large, undergoes torsion, or ruptures.
- Menstrual Irregularities: Associated with certain types of functional cysts.
- Acute Pain: Sudden-onset severe pain suggests torsion or rupture.
- Complications:
- Ovarian Torsion:
- Twisting of the ovary, often around a large cyst, causing severe, sudden pelvic pain, nausea, and vomiting. Surgical intervention is usually required to prevent ovarian damage.
- Cyst Rupture:
- Leads to sharp pelvic pain and, if bleeding is significant, can cause hemodynamic instability. Urgent evaluation and potential surgical management may be needed.
Diagnosis
- Imaging:
- Pelvic Ultrasound: First-line imaging modality to assess ovarian cysts.
- Functional Cysts: Appear as simple, unilocular cysts with thin walls.
- Dermoid Cysts: Show echogenic material, possibly with calcifications.
- Endometriomas: Appear as homogeneous masses with “ground-glass” echogenicity.
- Malignant Features: Include thick septations, solid areas, irregular borders, and ascites.
- Laboratory Tests:
- Serum hCG: Performed to rule out pregnancy, especially in reproductive-aged women with an ovarian cyst.
- CA-125:
- A tumor marker often elevated in ovarian malignancy but can be nonspecifically elevated in benign conditions (e.g., endometriosis).
- More specific in postmenopausal women and helps guide the management of suspicious cysts.
Management
Observation
Functional Cysts:
- Often resolve spontaneously; simple cysts <5 cm in premenopausal women can be monitored with repeat ultrasound in 1–3 months.
- Postmenopausal Women:
- Simple cysts <5 cm with normal CA-125 can be observed with serial imaging if no other concerning features are present.
Medical Therapy
Hormonal Contraceptives:
- Can prevent the formation of new functional cysts, though they do not hasten the resolution of existing cysts.
- Useful in women with recurrent cysts who also desire contraception.
Surgical Management
Indications for Surgery:
- Persistent cysts, large cysts (>5–10 cm), symptomatic cysts, or cysts with suspicious ultrasound features.
- Emergency surgery is required for acute complications like torsion or rupture.
- Cystectomy: Removal of the cyst while preserving the ovary, typically preferred for benign cysts in younger women.
- Oophorectomy: Removal of the ovary; often indicated for large or suspicious cysts, especially in postmenopausal women.
Key Points
- Ovarian Cysts can be functional (e.g., follicular, corpus luteum) or pathologic (e.g., dermoid, endometrioma, cystadenoma).
- Diagnosis primarily involves pelvic ultrasound, with CA-125 levels used in postmenopausal women to assess malignancy risk.
- Management includes observation for small, simple cysts, hormonal therapy for recurrent functional cysts, and surgery for symptomatic, large, or suspicious cysts.
- Complications like torsion and rupture may present with acute abdominal pain and often require surgical intervention.