Clinical laboratory medical standard and BDS EN ISO/IEC 17043:2010.


NSVOK carries out an external assessment of the quality of clinical laboratories, according to Ordinance No. 1/ 14.01.2014. SG No. 31/01/2014 for the approval of the Clinical Laboratory Medical Standard, BDS EN ISO/IEC 17043:2010.

Determination of value

NSVOK is built to apply each of the methods for determining value (assigned value) - declared value, agreed value, reference determined value, etc. When determining the "assigned value", by means of an agreed value, the "robust average" method in the sense of ISO 13528:2005(E) is applied.

After analyzing the entered measurement results, each of the participants has access to the statistically processed results:

Histograms of all participants' scores and their score indicated as a marker.
Graph of results for each analyte for the last year.
The following statistics: n, mean, SD and CV%, mean ± d% (permissible percentage deviation from the agreed value of the total group), the recommended d% calculated in the confidence interval.
Results such as d% of concordant value and Z-score (SDI)


Z-score (SDI) is assessed on the following scale:

"good" - SDI in the range +2 to -2.
"satisfactory" - SDI in the range +2 to +3, respectively –2 to -3
"mismatch" - SDI greater than +3, respectively less than -3


Checking that employees understand and follow the measurement procedure.
Checking that all details of the measurement procedure are followed.
Checking equipment calibration, reagent composition and condition.
Replace questionable equipment or reagents.
Comparative tests with personnel, equipment and/or reagents of another laboratory.


A certificate of participation in NSVOK is valid for concluding a contract with the NHSV and is issued according to the rule for Clinical Chemistry N-2, and for other programs N-1, where N is the number of control studies in one year. The Certificate indicates the identification data of the medical facility, the period for which it was issued and all Programs and analytes on which an external quality assessment was carried out.

Certificate english

Arising disputes between the participant and the coordinator are resolved in a spirit of goodwill and understanding by the Verification Committee or the General Assembly, and in case of impossibility before the civil courts according to the procedure provided by law