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Ovarian Cysts for USMLE Step 1

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Ovarian Cysts for the USMLE Step 1 Exam
Ovarian Cysts
  • Definition:
    • Ovarian cysts are fluid-filled sacs on or within the ovary, most of which are benign and functional, arising as part of the normal menstrual cycle. They are classified as functional or pathologic, with functional cysts being the most common in reproductive-aged women.
  • Types of Ovarian Cysts:
Functional Cysts
    • Functional cysts are related to normal ovulation and typically resolve without treatment.
Follicular Cysts:
    • Develop when a follicle fails to release an egg and continues growing.
    • Usually asymptomatic, self-resolving within one to three menstrual cycles.
Corpus Luteum Cysts:
    • Form if the corpus luteum doesn’t degenerate after ovulation and fills with fluid.
    • Can cause pain and irregular menstrual bleeding but typically resolves on its own.
Theca Lutein Cysts:
    • Associated with elevated human chorionic gonadotropin (hCG) levels, often seen in pregnancy, molar pregnancy, or fertility treatments.
    • Typically regress once hCG levels normalize.
Ovarian Cysts
Pathologic Cysts
    • Pathologic cysts result from abnormal cell growth and may be benign or malignant.
Dermoid Cysts (Mature Cystic Teratomas):
    • Arise from germ cells and can contain different tissue types (e.g., hair, teeth, skin).
    • Asymptomatic unless large or complicated by torsion.
Endometriomas:
    • Caused by endometriosis, filled with thick, dark blood (“chocolate cysts”).
    • Associated with pelvic pain, dysmenorrhea, and sometimes infertility.
Cystadenomas:
    • Benign epithelial tumors that may be serous (thin fluid) or mucinous (thick, gelatinous fluid).
    • Can grow large, causing abdominal discomfort or distension.
Clinical Presentation
  • Symptoms:
    • Often asymptomatic and discovered incidentally. Symptomatic cysts may present with:
    • Pelvic Pain: Usually mild but can be severe if the cyst is large, ruptures, or causes torsion.
    • Menstrual Irregularities: Some cysts may lead to delayed or irregular periods.
  • Complications:
    • Ovarian Torsion:
    • Twisting of the ovary on its ligamentous supports, usually involving a large cyst.
    • Sudden onset of severe, unilateral pelvic pain, often with nausea and vomiting; requires emergency surgical intervention.
    • Cyst Rupture:
    • Can cause sharp, sudden pelvic pain and internal bleeding.
    • Symptoms may include acute pain, often with some degree of intra-abdominal bleeding depending on cyst size and location.
Diagnosis
  • Imaging:
    • Pelvic Ultrasound: First-line imaging modality for assessing ovarian cysts.
    • Functional Cysts: Typically appear as simple, unilocular, and thin-walled on ultrasound.
    • Dermoid Cysts: Echogenic material due to hair or calcifications.
    • Endometriomas: Display characteristic “ground-glass” echogenicity due to thick blood content.
    • Suspicious Features for Malignancy: Include solid areas, thick septations, irregular borders, and ascites.
  • Laboratory Tests:
    • Serum hCG: Used to rule out pregnancy, especially in reproductive-aged women presenting with an ovarian mass.
    • CA-125:
    • Elevated in some ovarian cancers, especially in postmenopausal women.
    • Can be falsely elevated in benign conditions, such as endometriosis or pelvic inflammatory disease, so it is more specific in postmenopausal women.
Management
Observation
Functional Cysts:
    • Most resolve spontaneously; asymptomatic cysts <5 cm in premenopausal women are often monitored with repeat ultrasound in 1-3 months.
    • Postmenopausal Women:
    • Simple cysts <5 cm with normal CA-125 may be observed with serial imaging.
Surgical Management
Indications for Surgery:
    • Persistent or symptomatic cysts, large cysts (>5-10 cm), or cysts with concerning ultrasound features.
    • Immediate surgery is needed for complications like torsion or rupture.
Types of Surgery:
    • Cystectomy: Removal of the cyst while preserving ovarian tissue.
    • Oophorectomy: Removal of the ovary, often indicated for larger or suspicious cysts, particularly in postmenopausal women.
Key Points
  • Ovarian Cysts are commonly classified as functional (e.g., follicular and corpus luteum) or pathologic (e.g., dermoid, endometrioma).
  • Diagnosis relies primarily on pelvic ultrasound, with CA-125 used in postmenopausal women for malignancy risk assessment.
  • Management often involves observation for small, simple cysts, while larger, symptomatic, or suspicious cysts may require surgical intervention.
  • Complications such as ovarian torsion and cyst rupture can present with acute abdomen and require prompt surgical management.

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