Our department also often receives viscous fluid samples for analysis. Recently, we have been taking a closer look at the challenges involved in analysis of pancreatic cyst fluid samples. As others have mentioned, samples such as these are precious and obtained via complex, invasive procedures and so we feel that we should do as much as we can with them. During our investigation of pancreatic cyst fluid samples, we have noted that sample viscosity appears to be less severe in samples that have been stored at -20 degrees C, then thawed. A freeze-thaw cycle may help to 'break-up' the mucous, similar to pre-analytical treatment of saliva samples. We now routinely store pancreatic cyst fluid samples in the freezer overnight and thaw prior to analysis. However, we do still see some samples that are simply too thick and cannot be analysed .
There are also other problems when using assays that have been validated for analysis of serum/plasma samples to analyse fluid samples, such as potential matrix effects and interferences. For example, we have found that pancreatic cyst fluid CEA and CA 19-9 measurements (useful tests in the differentiation of pancreatic cysts - particularly CEA) often exhibit significant non-linearity on sample dilution, suggesting interference/matrix effects/high dose hook (data presented at Focus this year). The lack of CE marked tests for fluid analysis, lack of EQA schemes for fluid analysis and difficulties in performing in-house validation (due to scarcity of suitable samples etc.) can definitely make analysis of these samples quite challenging.
Chris Boot
University Hospitals Birmingham
------ACB discussion List Information--------
This is an open discussion list for the academic and clinical community working in clinical biochemistry.
Please note, archived messages are public and can be viewed via the internet. Views expressed are those of the individual and they are responsible for all message content.
ACB Web Site
http://www.acb.org.uk
Green Laboratories Work
http://www.laboratorymedicine.nhs.uk
List Archives
http://www.jiscmail.ac.uk/lists/ACB-CLIN-CHEM-GEN.html
List Instructions (How to leave etc.)
http://www.jiscmail.ac.uk/
|