Cancer Antigen 125 (CA-125) in Ascitic Fluid
This test measures levels of CA-125, a protein linked to certain cancers, in fluid collected from an abdominal swelling (ascites). It helps assess whether the fluid is due to cancer spread or another condition.
["CA-125 in ascitic fluid may help diagnose or monitor ovarian cancer or other conditions causing fluid buildup in the abdomen."]
Key facts at a glance
- LOINC
- 97743-9
- Short code
- CA125ASP
- Synonyms
- Cancer Ag125 Aspirate-aCnc
- Category
- chemistry
- Sample
- serum
- Container
- Sterile, leak-proof container for aspirate fluid; red-top or SST tube if serum comparison needed
- Units
- N/A
- Critical range
- 0.5 N/A – —
- Fasting
- false
- Population
- adult
- Sex
- female
- Age range
- ≥ 18 years
- Method
- Immunoassay (Electrochemiluminescence Immunoassay)
- CPT
- 86304
- SNOMED
- 104807008
- Specimen volume
- 2-5 mL of aspirate fluid
- Stability
- Refrigerated at 2-8°C: up to 48 hours; Frozen at -20°C or below: up to 30 days. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
Why This Test Is Done
Your doctor may order this test if you have abdominal swelling (ascites) and suspect ovarian cancer or another condition causing fluid buildup. It helps determine if the fluid contains cancer cells or if another cause, like liver disease or infection, is present.
What to Expect Before the Test
No special preparation is needed. The fluid is typically collected through a procedure called paracentesis, where a needle is used to drain fluid from the abdomen under sterile conditions.
What the Test Results Mean
Elevated levels of CA-125 in ascitic fluid may suggest ovarian cancer or other malignancies. However, CA-125 alone is not definitive—results are interpreted alongside clinical findings, imaging, and other tests.
Common Causes of Elevated Results
While ovarian cancer is a primary concern, other conditions—such as peritoneal carcinomatosis (cancer spread to the abdomen), endometriosis, or inflammatory diseases—can also raise CA-125 levels in ascitic fluid.
Reference range
No established reference range for CA 125 in aspirate specimens; clinical interpretation should be based on comparison with serum CA 125 levels, cytology results, and clinical context. Generally, aspirate fluid CA 125 levels are interpreted in conjunction with fluid analysis and imaging findings.N/A
No special patient preparation required. Inform the ordering physician of any recent surgeries, infections, or inflammatory conditions that may affect CA 125 levels.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance
Short name
CA-125 in Fluid from Abdominal Swelling
Frequently asked questions
How often do I need this test?
Can CA-125 levels change over time?
What if my fluid test is positive but I don’t have cancer?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 17, 2026. · Read our editorial policy