Ovarian Cysts in Postmenopausal Women: Management and Risk Assessment

1. Introduction and Purpose

Ovarian cysts are frequently discovered in postmenopausal women, often incidentally during imaging for other medical conditions. While the majority are benign, the possibility of malignancy necessitates a clear diagnostic and management pathway. This guideline aims to:

Clarify when ovarian masses can be managed within a general gynaecological service versus when referral to a specialist gynaecological oncology service is appropriate.

Help determine whether surgical or expectant (conservative) management is more suitable.

Avoid unnecessary surgery or costly invasive testing for benign simple cysts.

The guideline specifically focuses on cystic lesions 1 cm or more in size, as smaller lesions are considered "clinically inconsequential."

2. Diagnosis and Initial Investigations

Clinicians must be aware of the varied presentations and significance of ovarian cysts in postmenopausal women.

2.1 Presenting Symptoms

Acute abdominal pain: "In postmenopausal women presenting with acute abdominal pain, the diagnosis of an ovarian cyst accident should be considered (e.g. torsion, rupture, haemorrhage)."

Gynaecological investigations: Cysts may be identified during investigations for symptoms like postmenopausal bleeding.

Incidental findings: Many cysts are found incidentally during imaging for non-gynaecological conditions.

2.2 Initial Assessment

"It is recommended that ovarian cysts in postmenopausal women should be initially assessed by measuring serum cancer antigen 125 (CA125) level and transvaginal ultrasound scan." This is crucial for triaging women and estimating the risk of malignancy.

2.3 History and Clinical Examination

Medical History: "A thorough medical history should be taken from the woman, with specific attention to risk factors and symptoms suggestive of ovarian malignancy, and a family history of ovarian, bowel or breast cancer."

Family History: A significant family history (e.g., two or more first-degree relatives with ovarian cancer, or one with ovarian cancer and one with early-onset breast cancer) warrants "referral to the Regional Cancer Genetics service."

Symptoms: Vague abdominal symptoms (e.g., persistent abdominal distension, pelvic pain, increased urinary urgency) "have greater significance in postmenopausal women, particularly over 50 years of age, if experienced persistently or on a frequent basis, or in those with a significant family history."

Physical Examination: "A full physical examination of the woman is essential and should include body mass index, abdominal examination to detect ascites and characterise any palpable mass, and vaginal examination." Features like an irregular, solid, fixed, nodular, or bilateral mass, or association with ascites, are consistently linked to adnexal malignancy.

2.4 Blood Tests

CA125: "CA125 should be the only serum tumour marker used for primary evaluation as it allows the Risk of Malignancy Index (RMI) of ovarian cysts in postmenopausal women to be calculated." However, "CA125 levels should not be used in isolation to determine if a cyst is malignant" as a normal value "does not exclude ovarian cancer due to the nonspecific nature of the test." Elevated CA125 can also occur due to benign gynaecological and non-gynaecological conditions.

Other Tumour Markers: "There is currently not enough evidence to support the routine clinical use of other tumour markers, such as human epididymis protein 4 (HE4), carcinoembryonic antigen (CEA), CDX2, cancer antigen 72-4 (CA72-4), cancer antigen 19-9 (CA19-9), alphafetoprotein (α-FP), lactate dehydrogenase (LDH) or beta-human chorionic gonadotrophin (β-hCG), to assess the risk of malignancy in postmenopausal ovarian cysts."

2.5 Imaging

Transvaginal Ultrasound (TVS): "A transvaginal pelvic ultrasound is the single most effective way of evaluating ovarian cysts in postmenopausal women."

It should be performed by "trained clinicians with expertise in gynaecological imaging."

"The morphological description and subjective assessment of the ultrasound features should be clearly documented to allow calculation of the risk of malignancy."

Simple cysts: Characterized by round/oval shape, thin walls, posterior acoustic enhancement, anechoic fluid, and absence of septations or nodules. These are benign in 95-99% of cases.

Complex cysts: Presence of complete septation (multilocular), solid nodules, or papillary projections, which indicate increased malignancy risk (8% for multilocular, 36-39% for solid elements).

Transabdominal Ultrasound (TAS): "Transabdominal ultrasound should not be used in isolation. It should be used to provide supplementary information to transvaginal ultrasound particularly when an ovarian cyst is large or beyond the field of view of transvaginal ultrasound."

Doppler and 3D Ultrasound: "Colour flow Doppler studies are not essential for the routine initial assessment of ovarian cysts in postmenopausal women." Similarly, "Spectral and pulse Doppler indices should not be used routinely" and "Three-dimensional ultrasound morphologic assessment does not appear to improve the diagnosis of complex ovarian cysts and its routine use is not recommended."

CT, MRI, PET-CT: "CT, MRI and positron emission tomography (PET)-CT scans are not recommended for the initial evaluation of ovarian cysts in postmenopausal women."

CT Scan: "CT should not be used routinely as the primary imaging tool for the initial assessment... because of its low specificity, its limited assessment of ovarian internal morphology and its use of ionising radiation." However, "If... malignant disease is suspected, a CT scan of the abdomen and pelvis should be arranged, with onward referral to a gynaecological oncology multidisciplinary team."

MRI: "MRI should be used as the second-line imaging modality for the characterisation of indeterminate ovarian cysts when ultrasound is inconclusive." It is a valuable problem-solving tool, especially with contrast enhancement, but its routine use is limited by cost and availability.

PET-CT Scan: "Current data do not support the routine use of PET-CT scanning in the initial assessment of postmenopausal ovarian cysts. Data suggest there is no clear advantage over transvaginal ultrasonography."

3. Risk of Malignancy Index (RMI)

The RMI is a crucial tool for triaging patients.

Recommended Index: "The ‘RMI I’ is the most utilised, widely available and validated effective triaging system for women with suspected ovarian cancer."

Calculation: RMI = U (Ultrasound Score) x M (Menopausal Status) x CA125.

U (Ultrasound Score): 0 points for no suspicious features, 1 point for one feature (multilocular, solid areas, metastases, ascites, bilateral lesions), 3 points for two or more features.

M (Menopausal Status): 3 for postmenopausal women (as per this guideline's focus).

CA125: Serum level in iu/ml.

Thresholds: "Although a RMI I score with a threshold of 200 (sensitivity 78%, specificity 87%) is recommended... some centres utilise an equally acceptable threshold of 250 with a lower sensitivity (70%) but higher specificity (90%)."

Action based on RMI: "CT of the abdomen and pelvis should be performed for all postmenopausal women with ovarian cysts who have a RMI I score greater than or equal to 200, with onward referral to a gynaecological oncology multidisciplinary team."

3.1 Other Scoring Systems

IOTA classification: Based on specific ultrasound expertise, it "has comparable sensitivity and specificity to RMI and forms an alternative for those experienced in this technique."

OVA1® and ROMA: These "require specific assays which may make routine use impractical" and are not currently recommended for routine clinical use due to insufficient evidence.

4. Management of Ovarian Cysts

Management decisions depend on the likelihood of malignancy, patient symptoms, and surgical fitness.

4.1 Conservative Management

Criteria: "Asymptomatic, simple, unilateral, unilocular ovarian cysts, less than 5 cm in diameter, have a low risk of malignancy. In the presence of normal serum CA125 levels, these cysts can be managed conservatively, with a repeat evaluation in 4–6 months."

Discharge: "It is reasonable to discharge these women from follow-up after 1 year if the cyst remains unchanged or reduces in size, with normal CA125, taking into consideration a woman’s wishes and surgical fitness."

Symptomatic/Complex Cysts: "If a woman is symptomatic, further surgical evaluation is necessary." Similarly, "A woman with a suspicious or persistent complex adnexal mass needs surgical evaluation."

4.2 Role of Aspiration

"Aspiration is not recommended for the management of ovarian cysts in postmenopausal women except for the purposes of symptom control in women with advanced malignancy who are unfit to undergo surgery or further intervention." This is due to poor diagnostic accuracy and the risk of cancer cell spillage.

4.3 Surgical Management

Laparoscopy:

Eligibility: "Women with a RMI I of less than 200 (i.e. at low risk of malignancy) are suitable for laparoscopic management."

Surgeon Experience: "Laparoscopic management... should be undertaken by a surgeon with suitable experience."

Procedure: "Laparoscopic management... should comprise bilateral salpingo-oophorectomy rather than cystectomy."

Counselling: "Women undergoing laparoscopic salpingo-oophorectomy should be counselled preoperatively that a full staging laparotomy will be required if evidence of malignancy is revealed."

Specimen Removal: "Where possible, the surgical specimen should be removed without intraperitoneal spillage in a laparoscopic retrieval bag via the umbilical port." Transvaginal extraction is also acceptable.

Laparotomy:

Indications: "All ovarian cysts that are suspicious of malignancy in a postmenopausal woman, as indicated by a RMI I greater than or equal to 200, CT findings, clinical assessment or findings at laparoscopy, require a full laparotomy and staging procedure."

Referral for Malignancy: "If a malignancy is revealed during laparoscopy or from subsequent histology, it is recommended that the woman be referred to a cancer centre for further management."

5. Location and Specialist Management

Appropriate Location: "The appropriate location for the management should reflect the structure of cancer care in the UK."

Who should manage: "While a general gynaecologist might manage women with a low risk of malignancy (RMI I less than 200) in a general gynaecology or cancer unit, women who are at higher risk should be managed in a cancer centre by a trained gynaecological oncologist, unless the multidisciplinary team review is not supportive of a high probability of ovarian malignancy." This is because optimal surgical cytoreduction and staging for ovarian cancer are more likely to be achieved by a gynaecological oncologist in a cancer center.

6. Clinical Algorithm Summary

The guideline provides a clear algorithm (see Appendix II in source) for managing postmenopausal ovarian cysts:

Cyst (1 cm or more) detected.

Measure CA125 and perform TVS ± TAS.

Calculate RMI I.

RMI I < 200 (low risk):

If asymptomatic, simple, < 5 cm, unilocular, unilateral: Consider conservative management with repeat CA125, TVS ± TAS in 4-6 months. Discharge if persistent/unchanged for 1 year with normal CA125.

If symptomatic, non-simple features, > 5 cm, multilocular, bilateral: Consider surgery (salpingo-oophorectomy, usually bilateral) by a suitably experienced surgeon, with MDT review for low likelihood of malignancy.

RMI I ≥ 200 (increased risk):

Perform CT scan (abdomen and pelvis).

Refer for gynaecological oncology MDT review.

Proceed to Laparotomy with full staging procedure by a trained gynaecological oncologist if high likelihood of malignancy.

If low likelihood after MDT review, individualize treatment (e.g., pelvic clearance) after discussion.

7. Future Research and Auditable Topics

The guideline also highlights areas for future research (e.g., optimum RMI I threshold, new tumour markers, follow-up studies) and auditable topics to ensure quality of care (e.g., proportion of high-RMI women referred to specialist teams, false-negative/positive rates in different surgical settings).