Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.
Ovarian cancer symptoms, CA125 and imaging
Obstetrics and gynaecology · UK scope · Sources checked 27 Aug 2026 · Clinical review pending
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Obstruction, thrombosis and respiratory compromise need acute care
Advanced ovarian cancer may present with bowel obstruction, massive ascites or pleural effusion, venous thromboembolism, sepsis, acute kidney injury or a painful torsion-like adnexal emergency.
Action: Assess airway, breathing, circulation, abdomen, urine output and thromboembolic features; stabilise, obtain urgent imaging and surgical or oncology review, and drain or decompress only through an indication-led specialist plan.
Overview
Recognise persistent ovarian-cancer symptom patterns and apply the April 2026 age-specific CA125, ultrasound, RMI and tissue-diagnosis pathway without false reassurance or indiscriminate screening.
Ovarian, fallopian-tube and primary peritoneal cancers commonly present through nonspecific abdominal or urinary change rather than a discrete adnexal complaint. Ask when symptoms began, how many days per month they occur, whether they are progressive and how they affect meals, clothing, bowel habit and activity. Persistent distension differs from intermittent bloating. Early satiety means inability to finish usual portions, not simply dietary preference. Record weight change, fatigue and family history alongside examination.
NICE highlights persistent or frequent symptoms, particularly more than twelve times monthly: abdominal distension, appetite loss or early satiety, pelvic or abdominal pain and increased urinary urgency or frequency, especially at age 50 or over. Unexplained weight loss, fatigue or altered bowel habit also support testing. A new IBS-like syndrome after 50 needs ovarian-cancer consideration. Conversely, one transient episode with a clear benign cause does not automatically require tumour markers.
Practice
Two practice questions
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Question 1 of 2
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Obstetrics and gynaecologyOriginal SBA
Applying the 2026 CA125 table
A 65-year-old has persistent early satiety and abdominal distension. Examination shows no mass or ascites, and serum CA125 is 26 IU/ml. What does current NICE guidance indicate next?
Sources and review status5 sources · checked 27 Aug 2026 · clinical review pending+
Sources
Sources and review status
National guidance is shown before implementation-dependent detail. Apply principles in context and verify current guidance when a decision affects care. Source check completed 27 Aug 2026; clinical approval remains outstanding.
Examine the abdomen for distension, ascites, tenderness, organomegaly and a mass, and offer pelvic examination when appropriate and acceptable. Ascites or a pelvic or abdominal mass not obviously fibroids is itself a suspected-cancer referral criterion. Do not delay that referral to obtain CA125. Acute pain with peritonism, vomiting or instability raises torsion, rupture, obstruction or another surgical emergency and leaves the routine marker pathway.
The April 2026 NG12 update introduced age-sensitive primary-care testing. For a symptomatic person aged 39 or younger, CA125 must not be used in isolation because performance is poor and non-epithelial tumours are relatively more important; consider an urgent direct-access abdominal and pelvic ultrasound. If it is normal, investigate other causes and provide return advice for symptoms becoming more frequent or persistent.
For symptomatic people aged 40 or over, measure serum CA125. Arrange urgent direct-access ultrasound when the value reaches the age-specific threshold: 35 IU/ml at 40 to 49, 31 at 50 to 59, 24 at 60 to 69, 25 at 70 to 79 and 31 at 80 or older. These cut-offs replaced the former single 35 IU/ml rule for older groups. A result below its threshold is not labelled universally normal and cannot negate a mass, ascites or progressive illness.
If ultrasound suggests ovarian cancer, refer to a gynaecological cancer service on the suspected-cancer pathway. When CA125 is below the applicable threshold, or it reaches threshold but ultrasound is normal, identify other explanations and investigate them. If none is found, advise the person to return when symptoms become more frequent, more persistent or otherwise concerning. Safety-netting is an active plan with a time or symptom trigger, not a closing phrase.
CA125 is a glycoprotein released with peritoneal and Müllerian irritation. It can rise in menstruation, pregnancy, endometriosis, fibroids, pelvic infection, liver disease, heart failure and other malignancies. Some early ovarian cancers and several histological subtypes do not raise it substantially. This biology explains both false positives and false negatives and why serial CA125 for asymptomatic average-risk population screening is not recommended.
Secondary care repeats or obtains CA125 and uses expert ultrasound to characterise morphology. NICE RMI I combines ultrasound features, menopausal status and CA125: RMI = U × M × CA125. The ultrasound score counts multilocularity, solid areas, metastases, ascites and bilateral lesions; U is 0 for no feature, 1 for one and 3 for two to five. M is 1 before menopause and 3 after menopause. An RMI I of 250 or more leads to specialist MDT referral.
If clinical findings, ultrasound and CA125 suggest cancer, CT of abdomen and pelvis establishes distribution and resectability, adding thoracic imaging when clinically indicated. MRI is not routine in the standard suspected-cancer pathway but can solve selected indeterminate adnexal questions. In a person under 40 with suspected ovarian malignancy, secondary care also measures AFP and beta-hCG to identify possible germ-cell disease rather than assuming epithelial cancer.
Tissue type determines treatment. When chemotherapy is planned for suspected advanced disease, obtain histology, or cytology only when histology is not appropriate, before treatment in all but exceptional cases discussed by the MDT with the patient. Image-guided core biopsy, laparoscopy or surgical resection may provide tissue. Avoid puncturing an apparently confined ovarian mass casually because rupture can alter stage and oncological surgery planning.
Management balances maximal safe cytoreduction, platinum-based systemic therapy and targeted maintenance according to stage, histology, homologous-recombination and BRCA status, resectability and fitness. Genetic and tumour testing should be embedded early because results affect treatment and relatives. Acute ascites, obstruction, malnutrition, pain and thrombosis require parallel supportive care rather than waiting for the complete anticancer plan.
Key points
The symptom signal is persistence and frequency, not one dramatic episode: distension, early satiety or appetite loss, pelvic or abdominal pain, and urinary urgency or frequency are key patterns, especially after age 50.
NICE NG12 changed in April 2026: age 39 or under with persistent suggestive symptoms should not be managed with CA125 alone; consider urgent direct-access ultrasound of abdomen and pelvis.
At age 40 or over, measure CA125 and use age-specific ultrasound thresholds: 35 IU/ml at 40–49, 31 at 50–59, 24 at 60–69, 25 at 70–79 and 31 at 80 or over.
These thresholds decide urgent ultrasound in symptomatic primary-care assessment; they are not universal normal ranges and do not diagnose cancer.
If ultrasound suggests ovarian cancer, refer through the suspected-cancer pathway. If CA125 is below the age threshold or ultrasound is normal, investigate other causes and safety-net increasing or persistent symptoms.
CA125 rises with many benign or non-ovarian conditions and can be low in early cancer; never use it as a population screening test or as the sole rule-out result.
In secondary care, ultrasound is the initial imaging study, RMI I equals ultrasound score multiplied by menopausal score and CA125, and a score of 250 or more warrants specialist MDT referral.
Aetiology
01
Tubal and ovarian epithelial origins
Many high-grade serous cancers arise from secretory epithelium of the distal fallopian tube before spreading across ovarian and peritoneal surfaces.
02
Hereditary DNA-repair failure
BRCA1, BRCA2 and other homologous-recombination pathway variants increase tubo-ovarian cancer risk and can influence platinum sensitivity, targeted treatment and family prevention.
03
Distinct histological pathways
Endometrioid and clear-cell cancers associate with endometriosis, while mucinous, low-grade serous, germ-cell and sex-cord tumours have different precursor biology and age distributions.
Pathophysiology
1
Transcoelomic spread
Malignant cells exfoliate across peritoneal surfaces, producing omental deposits, ascites and diffuse serosal disease that causes distension, pain and bowel dysfunction.
2
Lymphatic and pleural extension
Pelvic and para-aortic nodal spread may accompany transdiaphragmatic or pleural involvement, causing effusion, breathlessness and more advanced stage.
3
Marker release
Mesothelial and Müllerian irritation raises circulating CA125, creating sensitivity to tumour burden but poor specificity for cancer site or histological type.
4
Mechanical organ compromise
Tumour, adhesions and ascites restrict gastric capacity, compress ureters and obstruct bowel, explaining early satiety, renal injury and acute abdominal presentations.
Clinical features and red flags
Persistent symptom cluster
Frequent distension, early satiety, pelvic or abdominal pain and urinary urgency or frequency forming a new progressive pattern is more concerning than long-standing intermittent bloating.
Examination-led referral
Ascites or a non-fibroid pelvic or abdominal mass directly meets the suspected-cancer referral criterion and should not be held until biomarker testing is complete.
Younger symptomatic person
At age thirty-nine or younger, persistent suggestive symptoms warrant consideration of urgent ultrasound because CA125 alone is insufficient and tumour histology differs from older groups.
Age-threshold CA125
From age forty, the marker result is compared with the 2026 age-band cut-off for ultrasound rather than one universal value of thirty-five units per millilitre.
Advanced abdominal disease
Large-volume ascites, pleural symptoms, bowel obstruction, weight loss, thrombosis or renal compromise signals severe disease requiring urgent supportive and oncological assessment.
Red flags requiring action
Ascites or a pelvic or abdominal mass on examination that is not obviously uterine fibroids requires a suspected-cancer pathway referral without waiting for a CA125 result.
Persistent abdominal distension, early satiety, pelvic or abdominal pain, or urinary urgency and frequency occurring particularly more than twelve times monthly needs ovarian-cancer testing.
Investigations
01Serum CA125 in primary careFirst step
Why
Guide urgent ultrasound in symptomatic people aged 40 or over using the current age-specific thresholds.
Interpretation and limitations
Use 35, 31, 24, 25 and 31 IU/ml for the five successive age bands from 40 to 80-plus; values diagnose neither cancer nor benignity and must be read with symptoms and examination.
02Urgent ultrasound of abdomen and pelvis
Why
Identify an ovarian or peritoneal mass, ascites and malignant morphological features after symptoms or threshold CA125.
Interpretation and limitations
A suspicious scan triggers the suspected-cancer pathway; a normal scan prompts alternative investigation and safety-netting rather than permanent exclusion when symptoms persist.
03RMI I calculation
Why
Combine ultrasound morphology, menopausal status and CA125 to triage suspected ovarian cancer in secondary care.
Interpretation and limitations
Calculate U multiplied by M multiplied by CA125; a score of 250 or greater requires referral to a specialist multidisciplinary team under CG122.
04CT abdomen and pelvis with selective thorax
Why
Map nodal, peritoneal and distant spread and help assess the feasibility of cytoreductive surgery.
Interpretation and limitations
Use when CA125, ultrasound and clinical status suggest malignancy; CT distribution informs the MDT but cannot determine histological subtype without tissue.
Differential diagnosis
01
Functional or benign ovarian cyst
A simple cyst may be incidental or painful; morphology, menopausal status and interval behaviour distinguish it from a complex malignant mass.
02
Endometriosis or fibroids
Both can cause pelvic pain, masses and raised CA125, particularly before menopause, demonstrating why the biomarker cannot determine malignancy alone.
03
Gastrointestinal disease
Irritable bowel syndrome, colorectal or gastric cancer and inflammatory disease can produce distension, appetite change and altered bowel habit requiring parallel evaluation.
04
Hepatic or cardiac ascites
Portal hypertension and heart failure can cause ascites and CA125 elevation; examination and imaging must identify the underlying organ pattern without overlooking malignancy.
05
Metastasis to the ovary
Gastrointestinal, breast and endometrial primaries can involve ovaries, so histology and immunophenotype are essential before assigning an ovarian origin.
Management
01Primary-care detectionUse age and pattern togetherFirst stepA person presents with new persistent or frequent abdominal, appetite, pelvic or urinary symptoms suggestive of ovarian cancer.+
1Quantify symptom frequency and progression, examine for ascites or a mass and refer immediately if either examination finding is present.
2At 39 or younger consider urgent direct-access ultrasound without relying on CA125 alone; at 40 or older measure CA125 and apply the exact age-band threshold for ultrasound.
3AlternativeRefer a suspicious ultrasound through the cancer pathway, or investigate alternative causes and provide explicit return triggers when CA125 is below threshold or ultrasound is normal.
02Specialist diagnosisCharacterise risk and secure tissueUltrasound or clinical assessment suggests ovarian malignancy.+
1
Complications
01
Malignant bowel obstruction
Peritoneal implants, adhesions or bulky tumour can block bowel, causing vomiting, colic, distension, dehydration, aspiration risk and nutritional decline.
02
Ascites and pleural effusion
Fluid accumulation causes pain, reduced mobility, early satiety and respiratory compromise and may recur despite drainage until cancer control improves.
03
Venous thromboembolism
Ovarian cancer and major pelvic treatment create a strong prothrombotic state, leading to deep-vein thrombosis, pulmonary embolism or thrombosis at unusual sites.
04
Cachexia and frailty
Reduced intake, inflammation, ascites and repeated treatment cause muscle loss and functional decline that can limit surgery and systemic therapy tolerance.
05
Treatment and recurrence burden
Cytoreductive surgery and systemic treatment can cause organ, marrow, neurological and menopausal toxicity, while relapse may require repeated therapy and palliative support.
Monitoring and follow-up
For an initially reassuring primary-care pathway, record the alternative diagnosis pursued and a specific trigger or review point for continued distension, pain, early satiety or urinary change.
Trend CA125 only for a defined diagnostic or oncological purpose; a falling number does not substitute for clinical and imaging assessment when the person deteriorates.
Before and during treatment, monitor nutrition, weight, bowel function, ascites, renal function, thrombosis and performance status as well as tumour response.
Ensure pathology and germline or tumour genomic results reach the oncology plan and genetics pathway, including documented discussion of implications for relatives.
During follow-up, investigate new persistent abdominal symptoms or functional decline according to the recurrence pattern instead of relying on one routine marker value.
Special situations
The threshold changed by age
April 2026 NICE guidance lowers the ultrasound trigger below thirty-five units per millilitre for several older age bands, so memorising one historic cut-off is unsafe.
Under forty follows imaging logic
Lower disease prevalence and poorer CA125 discrimination in younger people mean persistent symptoms can justify ultrasound even without a marker-led threshold.
A mass outranks the marker
Ascites or a non-fibroid mass already qualifies for cancer referral; a low CA125 cannot demote that clinical finding.
RMI belongs to secondary care
The RMI uses structured ultrasound features and menopausal weighting to triage specialist involvement, not to screen asymptomatic people or replace tissue diagnosis.
Histology protects treatment choice
Core tissue distinguishes epithelial, germ-cell, sex-cord and metastatic tumours whose systemic regimens differ, preventing empiric chemotherapy for a marker-and-scan label.
Common pitfalls
01
Using 35 IU/ml as the ultrasound threshold for every age despite the April 2026 NG12 age-specific table.
02
Ordering CA125 alone for a symptomatic person aged thirty-nine or younger and treating a low result as exclusion.
03
Delaying referral for ascites or a palpable non-fibroid mass while waiting for tumour-marker testing.
04
Calling CA125 an ovarian-cancer screening test in an asymptomatic average-risk population.
05
Discharging persistent symptoms permanently after one normal ultrasound without investigating other causes or giving a return plan.
06
Starting chemotherapy from imaging alone when safe histological confirmation is feasible and no exceptional MDT rationale exists.
When CA125, ultrasound and clinical status suggest malignancy, CT abdomen and pelvis maps extent, adding thorax when indicated; histological diagnosis is expected before cytotoxic chemotherapy except in exceptional MDT-agreed circumstances.
New symptoms resembling irritable bowel syndrome at age 50 or over should trigger ovarian-cancer assessment because first presentation of IBS is uncommon at that age.
Vomiting, absolute constipation, abdominal distension and colicky pain suggest bowel obstruction and require same-day surgical and oncology assessment.
Unilateral leg swelling, sudden breathlessness, chest pain, hypoxia or haemoptysis suggests cancer-associated thrombosis and needs emergency investigation.
05Histology and genomic testing
Why
Confirm tumour type before chemotherapy and identify inherited or tumour variants relevant to treatment.
Interpretation and limitations
Core biopsy or surgical tissue is preferred over cytology when feasible; BRCA and broader testing follows the epithelial subtype and national genomic pathway, with consent and family implications explained.
Obtain CA125 if not already measured, perform expert ultrasound and calculate RMI I, referring scores of 250 or more to the specialist gynaecological oncology MDT.
2Use CT abdomen and pelvis, with thoracic assessment when indicated, to map disease and plan the safest route to cytoreduction or biopsy.
3Secure histology before cytotoxic chemotherapy except in exceptional MDT-agreed circumstances, adding age- and phenotype-specific markers and genomic testing.
03Complication and treatmentStabilise while defining oncological intentCancer is confirmed or suspected with obstruction, ascites, thrombosis, malnutrition or organ dysfunction.+
1Treat bowel obstruction, respiratory compromise, thrombosis, infection, renal injury and pain promptly with surgical, medical, radiological and palliative expertise.
2Decide primary surgery versus biopsy and neoadjuvant treatment from disease distribution, ability to achieve meaningful cytoreduction, physiology and patient priorities.
3Use final histology, stage and molecular results to plan systemic and maintenance therapy, and establish symptom-led follow-up with hereditary-risk care where indicated.