Ovarian Cysts

Summary

Ovarian cysts are common fluid-filled sacs, usually benign and self-limiting in reproductive-aged women but more concerning in postmenopausal women due to malignancy risk. Classified as non-neoplastic or neoplastic, they are primarily diagnosed by ultrasound, with the Risk of Malignancy Index (RMI) guiding management. Small functional cysts are often observed, while complex or high-risk cysts may require surgery, with fertility-preserving approaches favored in younger women.

Definition

Ovarian cysts are fluid-filled sacs within the ovary and represent a common gynecological finding, particularly in premenopausal women where benign, physiological cysts predominate. While most ovarian cysts are asymptomatic and resolve spontaneously, careful evaluation is essential to exclude malignancy, especially in postmenopausal women or those with risk factors for ovarian cancer.

Keep in mind: 

• Most ovarian cysts in reproductive-aged women are benign and self-limiting.

Classification

Ovarian cysts are broadly categorized as non-neoplastic (functional and pathological) and neoplastic (benign or malignant).

1. Non-Neoplastic Cysts

Functional Cysts

Functional cysts arise from normal ovarian physiology and are the most common ovarian cysts in reproductive-aged women. Rarely exceed 7 cm and usually resolve spontaneously. They develop from either the dominant follicle or corpus luteum during the menstrual cycle.

• Follicular Cysts:

• Occur when the dominant follicle fails to rupture during the maturation phase.

• Typically unilateral, 3–8 cm in size, and asymptomatic.

• Larger cysts (>4 cm) may predispose to ovarian torsion.

• Most resolve spontaneously within 60–90 days.
  
  

• Corpus Luteum Cysts:

• Formed when the corpus luteum fails to regress after 14 days in the luteal phase.

• May be hemorrhagic, termed corpus hemorrhagicum.

• Clinical presentation includes dull lower abdominal pain, delayed menstruation, or acute pain with hemoperitoneum if ruptured.
  
  

• Theca Lutein Cysts:

• Large, bilateral cysts filled with straw-colored fluid, resulting from high β-hCG levels (e.g., molar pregnancy, choriocarcinoma, or ovulation induction therapy).

• May contribute to ovarian hirsutism.

• Spontaneous regression usually occurs postpartum or after resolution of hCG stimulation.
  
  

Pathological Non-Neoplastic Cysts

• Endometriomas: Also known as “chocolate cysts,” formed due to endometriosis with internal hemorrhage.

• Polycystic Ovaries: Ultrasound diagnosis of ovaries containing >12 antral follicles or volume >10 mL. “Ring of pearls” appearance is classic; isolated polycystic ovaries do not define polycystic ovarian syndrome (PCOS).

2. Neoplastic Cysts

Benign Neoplasms

• Epithelial Tumors.

• Germ Cell Tumors.

• Sex Cord-Stromal Tumors.
  
  

Diagnosis

• Ultrasound: The primary diagnostic tool; simple cysts are usually benign, while complex masses may indicate neoplasia, the cornerstone for diagnosis and follow-up.

• Serum Markers:

• β-hCG to rule out pregnancy.

• CA125, lactate dehydrogenase, and α-fetoprotein in women under 40 when germ cell tumors are suspected.

• Risk Assessment: The Risk of Malignancy Index (RMI) helps guide referral and management.

Risk of Malignancy Index (RMI)

Is a widely used preoperative tool designed to estimate the likelihood that an adnexal mass is malignant. It combines three clinical and diagnostic parameters: serum CA125 level (CA125), menopausal status (M), and ultrasound score (U). The formula is expressed as:

RMI=U×M×CA125

• Ultrasound score (U): The ultrasound scan is assessed for the presence of specific features: multilocular cysts, solid areas, metastases, ascites, and bilateral lesions. Each feature scores 1 point.

• U = 0 → no abnormal features

• U = 1 → one abnormal feature

• U = 3 → two to five abnormal features
  
  

• Menopausal status (M):

• M = 1 → premenopausal

• M = 3 → postmenopausal (defined as ≥1 year of amenorrhea or age >50 years with prior hysterectomy)
  
  

• Serum CA125: Measured in IU/ml, with values ranging from normal (<35 IU/ml) to several hundred or even thousands in malignant cases.

Also, malignant potential increases with age, complex morphology, family history, and genetic predisposition.

Imaging Characteristics

• Simple Cysts: Thin-walled, anechoic, and unilocular.

• Complex Cysts: May have septations, solid components, or calcifications (dermoid cysts often display hyperechoic nodules).

Complication

• Ovarian torsion 

• Ruptured ovarian cyst

• Hemorrhage

Management

Functional Cysts

• Observation:

• Simple cysts <7 cm are usually managed conservatively with repeat ultrasound in 6–8 weeks.

• Patients should be counseled regarding acute pain indicative of torsion.

• Oral contraceptives can reduce recurrence.

• Surgery:

• Laparoscopy is indicated for cysts >7 cm or persistent cysts despite suppression with contraception.
  
  

Benign Neoplasms

• Cystectomy: Preferred to preserve ovarian function; avoid intraperitoneal spillage to prevent chemical peritonitis.

• Oophorectomy: Considered if cystectomy is not feasible due to size or complexity.

Pregnancy-Associated Cysts

• Luteoma of Pregnancy: Rare, non-neoplastic, androgen-producing mass; usually regresses spontaneously postpartum.

• Theca Lutein Cysts: Benign, associated with elevated hCG, and regress spontaneously postpartum.
  
  

Postmenopausal Women

• Management is guided by RMI:

• Low (<25): Ultrasound follow-up for cysts <5 cm.

• Moderate (25–250): Bilateral oophorectomy; staging if malignancy detected.

• High (>250): Referral for staging laparotomy.

Remember 

• Conservative management is preferred in young women to preserve fertility; surgical intervention is guided by size, persistence, and malignancy risk.