Abstract
Preanalytical and analytical aspects of the quantitative method for the determination of haemoglobin in stool are essential for the evaluation of the test, the positivity of which is an indication for colonoscopy in the screening of colorectal tumors. The quality requirements for laboratory analysis require, according to standard ISO 15189, that variability be assessed at all stages of the test process.
The pre-analytical aspect is the collection and transport of the sample including the collection cassette (amount of stool, volume and composition of the extraction buffer), stool consistency, stability of the sample (time and temperature of transport). The analytical aspect is mainly the variability of immunochemical technology, different antibodies, buffers, standards and calibration of analysers.
Harmonization and standardization of hemoglobin determination in stool samples is the topic of the IFCC Working Group for Faecal Immunochemical Testing (WG-FIT).