APMIS 111: 291–9, 2003 Copyright C APMIS 2003 Printed in Denmark . All rights reserved ISSN 0903-4641 Terms used to describe urinary tract infections – the importance of conceptual clarification PER-ERIK LISS, 1 OLLE ASPEVALL, 2,3 DANIEL KARLSSON 4 and URBAN FORSUM 3 1 Department of Health and Society, Linköpings Universitet, 2 Karolinska Institutet, Department of Immunology, Microbiology, Pathology and Infectious Diseases, Division of Clinical and Oral Bacteriology, Huddinge University Hospital, Huddinge, 3 Department of Molecular and Clinical Medicine, Linköpings Universitet and 4 Department of Biomedical Engineering, Linköpings Universitet, Sweden Liss P-E, Aspevall O, Karlsson D, Forsum U. Terms used to describe urinary tract infections – the importance of conceptual clarification. APMIS 2003;111:291–9. Inaccuracies in medical language are detrimental to communication and statistics in medicine, and thereby to clinical practice, medical science and public health. The purpose of this article is to explore inconsistencies in the use of some medical terms: urinary tract infection, bacteriuria and urethral syndrome. The investigated literature was collected from medical dictionaries, textbooks, and articles indexed in Medline A . We found various practices regarding how the medical terms should be defined, and had great difficulty in interpreting the status of the statements under the heading of ‘definition’. The lesson to be learned, besides a reminder of the importance of clearly defined medical concepts, is that it must be explicitly stated whether what is presented as a definition is to be considered as defining criterion, as recognising criterion or as characteristic of the disease entity. Key words: Bacteriuria; characteristic; defining criterion; recognising criterion; urethral syndrome; urinary tract infection. Urban Forsum, Division of Clinical Microbiology, Linköpings Universitet, SE-58185 Linköping, Sweden. e-mail: urban.forsum/imk.liu.se A prerequisite for inter-professional communi- cation in medicine, and specifically for interac- tion with medical specialists, is that the lan- guage used should be clear and that the in- tended meaning should be preserved. Medical language, however, is not free from vagueness or ambiguity. These inaccuracies of medical lan- guage can have serious consequences not only for health care delivery but also for medical science and public health. Assessments of the validity of epidemiological investigations and comparison of the results of various investi- gations will become less secure. As an example to exemplify communication in medicine we have explored the area of urinary tract infec- Received June 10, 2002. Accepted November 25, 2002. 291 tions as presented in selected parts of the litera- ture. Bacteriuria is regarded as a very important sign in the diagnosis of urinary tract infection (1). Bacteria in the urine are quantified and identified taxonomically to the species level by urine culture. Bacteria from the indigenous flora of the urethra or genital tract can contaminate collected midstream urine while the patient is voiding. A chosen concentration, cut-off value, is thus used to distinguish bacteriuria from con- tamination. In the 1950s Kass et al. investigated the possi- bility of using quantitative culture. Prior to this, urine was cultured both quantitatively and qualitatively, i.e. culture of 0.5 ml on a blood agar plate, enrichment culture, and culture on a centrifuged specimen was performed (2). Kass