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HelpTest ID: 199PT Carbohydrate Antigen 19-9 (CA 19-9), Peritoneal Fluid
Reporting Name
CA 19-9, Peritoneal FluidUseful For
An adjunct to cytology to differentiate between malignancy-related ascites and benign causes of ascites formation
Specimen Type
PeritonealSpecimen Required
Patient Preparation: For 12 hours before specimen collection do not take multivitamins or dietary supplements containing biotin (vitamin B7), which is commonly found in hair, skin, and nail supplements and multivitamins.
Container/Tube: Plain, plastic, screw-top tube
Specimen Volume: 2 mL
Specimen Minimum Volume
0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Peritoneal | Frozen (preferred) | 90 days | |
| Ambient | 7 days | ||
| Refrigerated | 7 days |
Reference Values
An interpretive report will be provided.
Day(s) Performed
Monday through Saturday
Test Classification
This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
86301
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| 199PT | CA 19-9, Peritoneal Fluid | 50781-4 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 199PN | CA 19-9, Peritoneal Fluid | 50781-4 |
| SITEE | Site | 39111-0 |
Clinical Information
Malignancy accounts for approximately 7% of cases of ascites formation. Malignant disease can cause ascites by various mechanisms, including peritoneal carcinomatosis (53%), massive liver metastasis causing portal hypertension (13%), peritoneal carcinomatosis plus massive liver metastasis (13%), hepatocellular carcinoma plus cirrhosis (7%), and chylous ascites due to lymphoma (7%). The evaluation and diagnosis of malignancy-related ascites is based on the patient clinical history, ascites fluid analysis, and imaging tests.
The overall sensitivity of cytology for the detection of malignancy-related ascites ranges from 58% to 75%. Cytology examination is most successful in patients with ascites related to peritoneal carcinomatosis, as viable malignant cells are exfoliated into the ascitic fluid. However, only approximately 53% of patients with malignancy-related ascites have peritoneal carcinomatosis. Patients with other causes of malignancy-related ascites almost always have a negative cytology.
Carbohydrate antigen 19-9 (CA 19-9) is a modified Lewis(a) blood group antigen. CA 19-9 may be elevated in the serum patients with gastrointestinal malignancies, such as cholangiocarcinoma, pancreatic cancer, or colon cancer. Measurement of CA 19-9 in ascitic fluid is sometimes used in combination with cytology for detecting malignancy-related ascites.
Interpretation
A peritoneal fluid carbohydrate antigen 19-9 (CA 19-9) concentration greater than 32 U/mL is suspicious, but not diagnostic, of a malignancy-related ascites. This clinical decision limit cutoff yielded 44% sensitivity and 93% specificity in a study of 137 patients presenting with ascites. However, ascites caused by malignancies not associated with increase serum CA 19-9 concentrations, including lymphoma, mesothelioma, leukemia, and melanoma, routinely had CA 19-9 concentrations less than 32 U/mL. Therefore, negative results should be interpreted with caution, especially in patients who have or are suspected of having a malignancy not associated with elevated CA 19-9 levels in serum.
Clinical Reference
1. Trape J, Molina R, Sant F: Clinical evaluation of the simultaneous determination of tumor markers in fluid and serum and their ratio in the differential diagnosis of serous effusions. Tumour Biol. 2004 Sep-Dec;25(5-6):276-281
2. Sari R, Yildirim B, Sevinc A, Bahceci F, Hilmioglu F: The importance of serum and ascites fluid alpha-fetoprotein, carcinoembryonic antigen, CA 19-9, and CA 15-3 levels in differential diagnosis of ascites etiology. Hepatogastroenterology. 2001 Nov-Dec;48(42):1616-1621
3. Block DR, Algeciras-Schimnich A: Body fluid analysis: clinical utility and applicability of published studies to guide interpretation of today's laboratory testing in serous fluids. Crit Rev Clin Lab Sci. 2013 Jul-Oct;50(4-5):107-124. doi: 10.3109/10408363.2013.844679
4. Jain T, Ram S, Kumar H, Saroch A, Sharma V, Singh H: Ascitic and serum levels of tumor biomarkers (CA 72-4, CA 19-9, CEA AND CA 125) in discrimination of cause of ascites: A prospective study. Arq Gastroenterol. 2022 Apr-Jun;59(2):198-203. doi: 10.1590/S0004-2803.202202000-37
Report Available
1 to 3 daysMethod Name
Immunoenzymatic Assay
Forms
If not ordering electronically, complete, print, and send an Oncology Test Request (T729) with the specimen.
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