Information on the Ring Trial Lab-focused QA:
prenatal diagnostics / amniotic fluid


The aim of the laboratory-focused quality assurance ring trials (chromosome analyses of lymphocytes from peripheral blood, amniotic fluid and chorionic villi long-term culture) is a retrospective consideration of the chromosome quality in the karyograms which were used for the appraisal by the laboratories participating in the external quality assurance.

Performance interval

Once per year.


In conjunction with the invitation to the laboratory-focused quality assurance ring trials, images of two karyograms and the associated metaphases of a case processed in the laboratory from three different months in each case are requested in accordance with the specification by the ring trial management. The participants upload these image documents in an anonymous form within the member area of


Through visual inspection, each karyogram and each metaphase will be evaluated with regard to the number of overlay points, brightness levels and the resolution of the chromosome banding quality.


The following parameters are to be evaluated: brightness levels of the chromosomes, the number of overlay points in the metaphase as well as the resolution of the chromosomes (banding quality). The various resolution levels of the chromosomes are specified in "An International System for Human Cytogenetic Nomenclature (ISCN)". The pass criteria for chromosome analysis from the individual tissues are defined in the current version of the "Guidelines of the German Federal Medical Council on Quality Assurance in Medical Laboratory Examinations (RiLiBÄK)".
Using the three parameters mentioned above, it is possible to assess the quality of chromosome diagnostics in individual laboratories.


Two different certificates can be issued (valid for two years):
  1. Certificate of successful participation and confirmation of compliance with the RiLiBÄK criteria. The certificate is valid for two years.
  2. If the RiLiBÄK criteria are not complied with, participation in the ring trial is confirmed.


Deutsches Ärzteblatt, Vol. 111, Issue 38, 19 September 2014, A 1583
An International System for Human Cytogenetic Nomenclature (ISCN)

Ring trial management

Prof. Dr. Jürgen Kunz
Labor Dr. Fenner und Kollegen
Bergstraße 14
20095 Hamburg
Tel. +49 40 30 95 54 31
Fax +49 40 30 95 55 30

Dr. rer. nat. Eva Daumiller
genetikum Stuttgart
Lautenschlagerstraße 23
70173 Stuttgart
Tel. +49 711 22 00 92 30
Fax +49 711 2 20 09 23 20


Ring Trial Laboratory-Focused QA - Criteria Banding Quality   Download document