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HelpTest Code 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
Method Name
Immunoenzymatic Assay
Performing Laboratory
Mayo Clinic Laboratories in Rochester
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 |
Reject Due To
| Gross hemolysis | Reject |
| Gross icterus | OK |
Reference Values
An interpretive report will be provided.
Day(s) Performed
Monday through Saturday
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.
Specimen Retention Time
14 daysTest 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.Report Available
1 to 3 daysForms
If not ordering electronically, complete, print, and send an Oncology Test Request (T729) with the specimen.