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HelpTest ID 199PT Carbohydrate Antigen 19-9 (CA 19-9), Peritoneal Fluid
Useful For
An adjunct to cytology to differentiate between malignancy-related ascites and benign causes of ascites formation
Method Name
Immunoenzymatic Assay
Reporting Name
CA 19-9, Peritoneal FluidSpecimen Type
PeritonealContainer/Tube: Plain, plastic, screw-top tube
Specimen Volume: 2 mL
Additional Information: Twelve hours before this blood test, do not take multivitamins or dietary supplements containing biotin or vitamin B7 that are commonly found in hair, skin and nail supplements and multivitamins.
Forms: If not ordering electronically, complete, print, and send an Oncology Test Request Form (T729) with the specimen
(http://www.mayomedicallaboratories.com/it-mmfiles/oncology-request-form.pdf)
Specimen Minimum Volume
0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Peritoneal | Frozen (preferred) | 90 days |
| Ambient | 7 days | |
| Refrigerated | 7 days |
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.
Reference Values
An interpretive report will be provided.
Cautions
Twelve hours before this blood test, do not take multivitamins or dietary supplements containing biotin or vitamin B7 that are commonly found in hair, skin and nail supplements and multivitamins.
Do not use peritoneal fluid carbohydrate antigen 19-9 (CA 19-9) levels concentration as absolute evidence of the presence or the absence of malignant disease. The CA 19-9 result should be interpreted in conjunction with information from the clinical evaluation of the patient and other diagnostic procedures.
Approximately 10% of the Caucasian population does not express CA 19-9 due to the deficiency of a fucosyltransferase enzyme. Consequently, low values in these individuals are not informative regarding malignancy-related ascites.
Immunometric assays can, in rare occasions, be subject to interferences such as "hooking" at very high analyte concentrations (false-low results) and heterophilic antibody interference (false-high results). If the clinical picture does not fit the laboratory result, these possibilities should be considered.
CA 19-9 values are method-dependent; therefore, the same method should be used to serially monitor patients.
Day(s) Performed
Monday through Friday; Varies
Report Available
Same day/1 dayPerforming Laboratory
Mayo Medical Laboratories in Rochester
Test Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.CPT Code Information
86301