Ovarian Cysts

Ovarian cysts are fluid-filled sacs within or on the surface of the ovary. They are an extremely common finding across the reproductive lifespan.

The commonest category is physiological, functional cysts, which reflect normal ovarian follicular activity and generally resolve spontaneously without specific treatment. Other types span benign neoplastic cysts and, less commonly, malignant ovarian tumours.

The clinical priority is accurate risk stratification, based on the woman's age, menopausal status and cyst characteristics on imaging. This separates the great majority of benign, often self-resolving cysts from the smaller proportion that need further evaluation or intervention.

Classification and pathophysiology

• Functional cysts are the commonest category overall. They occur only in ovulating women and characteristically resolve spontaneously within one to a few menstrual cycles without specific treatment.
• Follicular cysts reflect failure of a dominant follicle to rupture at ovulation, with continued growth of the unruptured follicle.
• Corpus luteal cysts reflect persistence and continued growth of the corpus luteum after ovulation, sometimes with internal haemorrhage.
• Dermoid cysts (mature cystic teratoma) contain tissue from all three embryological germ layers, including recognisable elements such as hair, teeth or sebaceous material. They are a common benign ovarian neoplasm, particularly in younger women.
• Serous and mucinous cystadenoma are benign epithelial tumours.
• Endometrioma is a characteristic manifestation of endometriosis.
• The likelihood of malignancy varies with age and menopausal status. Risk is substantially lower in premenopausal women, in whom the great majority of cysts are benign and often functional.
• In postmenopausal women any persistent ovarian cyst carries a higher relative likelihood of malignancy, because no ongoing physiological follicular activity is expected. This principle directly informs risk stratification and management.

• The great majority of ovarian cysts, particularly smaller functional cysts, are asymptomatic. They are found incidentally on pelvic examination or on imaging done for an unrelated indication.
• When symptomatic, cysts cause pelvic pain or discomfort, reflecting cyst size, internal haemorrhage or, less commonly, torsion or rupture. Menstrual irregularity is less common.
• Acute, severe pelvic pain may reflect cyst rupture or ovarian torsion. Rupture is particularly relevant with a corpus luteal cyst, which is characteristically somewhat vascular.
• Ovarian torsion is a genuine gynaecological emergency requiring prompt recognition and treatment. Either presentation warrants urgent clinical assessment.
• Larger cysts may produce a palpable abdominal or pelvic mass with pressure symptoms, including urinary frequency from bladder pressure or, less commonly, bowel symptoms.
• The size and growth pattern of a cyst bear on symptomatic burden and, during surveillance, on the assessment of malignancy risk.
• Explore associated symptoms that suggest an alternative or coexisting diagnosis. Cyclical pain suggests endometrioma.
• Systemic symptoms (weight loss, bloating or altered bowel habit) raise concern for malignancy, particularly in an older or postmenopausal woman.

• Pelvic ultrasound is the standard first-line imaging investigation. It characterises cyst size and internal architecture (simple versus complex, septations, solid components, papillary projections). Structured, standardised risk assessment systems support risk stratification for malignancy.
• Serum CA-125 is non-specific and is elevated in many benign conditions as well as ovarian malignancy, including endometriosis, fibroids and pelvic inflammatory disease.
• It forms part of the risk of malignancy index, which combines ultrasound findings, menopausal status and CA-125 level. The index is commonly used to support risk stratification, particularly in postmenopausal women.
• For a premenopausal woman with a small, simple cyst and no concerning feature, repeat ultrasound after a defined interval (typically six to twelve weeks). This confirms the expected spontaneous resolution of a presumed functional cyst and avoids unnecessary intervention.
• Any cyst with concerning features on imaging (complex morphology, solid components, or significant, rapid growth), or any persistent cyst in a postmenopausal woman, warrants further evaluation and, generally, specialist gynaecological referral.

• Small, simple functional cysts in premenopausal women without concerning symptoms or imaging features are managed with reassurance and interval repeat ultrasound to confirm spontaneous resolution. No specific treatment is needed, as the natural history is benign and self-limiting.
• Simple analgesia is appropriate for cyst-related discomfort. More significant, acute pain warrants prompt evaluation to exclude torsion or significant rupture.
• Surgical management is considered for persistent, symptomatic cysts, cysts with concerning imaging features, and larger cysts causing significant symptoms. It is typically laparoscopic cystectomy, aiming to preserve normal ovarian tissue where feasible.
• The surgical approach and extent are individualised according to the woman's age, fertility considerations and cyst characteristics.
• Postmenopausal ovarian cysts with any concerning feature, or that persist on interval reassessment, generally warrant specialist gynaecological referral.
• Where malignancy risk is significant on structured risk assessment, refer to gynaecological oncology, given the higher relative likelihood of malignancy in this population.
• Individualised counselling on the nature and likely natural history of the cyst, with clear guidance on any recommended follow-up imaging or further evaluation, underpins risk-stratified management of this extremely common gynaecological finding.