Cystic fibrosis is a congenital genetic disorder involving mutations in the CFTR gene. Due to the scale of the prevalence of the disease, screening for cystic fibrosis has been carried out in Poland since 2009 and thanks to this, it has been noted that the results obtained indicate a different category, in addition to those confirming the disease and those excluding it. We are talking about an uncertain result, i.e. one where, in the case of a positive test result, no clinical symptoms are observed and, therefore, confirmation of the diagnosis, as well as its exclusion, is impossible.