Is the urethral smear necessary in asymptomatic men attending a genitourinary medicine clinic?

Urethral microscopy has long been an integral part of screening for non-gonococcal urethritis (NGU) in men.1 This made sense when reliable tests were not available for chlamydia, although it has long been recognised that the urethral smear is a poor investigation, having high rates of both inter-observer2 and intra-observer 2,3 error (hardly surprising when one pauses to consider how the test is carried out). Another important observation, made by Swartz and Kraus,1 is that more than one half of cases of asymptomatic urethritis resolve after 1 week without any treatment. Although a number of microorganisms are associated with NGU, no pathogen is isolated in the majority of patients (table 1), particularly in asymptomatic men.4,5,6,7,8,9,10,11,12 Moreover, there is no evidence that pathogen-negative NGU is a sexually transmitted infection (STI).13 Hence many patients are unnecessarily labelled as having an STI with all the associated implications for themselves and their partners. Now that accurate tests (nucleic acid amplification tests (NAATs)) are routinely available for the important pathogenic agent known to cause NGU, Chlamydia trachomatis, is it still useful to perform urethral microscopy in all men attending STI clinics even when symptoms are absent? We believe not and present our argument below in the form of answers to the questions that reflective clinicians will ask themselves when confronted with this issue.

WILL IMPORTANT PATHOLOGY BE MISSED IN THE MEN?

There is no evidence that cases of C trachomatis infection would be missed. Although the sensitivity of chlamydia assays is not 100%, more modern NAATs such as the Aptima assay from Gen-Probe Inc (San Diego, …