For a clinical guideline to be of use, it needs to make clear recommendations for practice based on the available evidence. But what should be recommended when the evidence is finely balanced, limited and/or contradictory? An example of this is whether or not men without symptoms should be screened for non-specific urethritis (NSU)—a decision faced by virtually all clinicians working in sexually transmitted infection (STI) clinics every day. In many countries this practice was abandoned many years ago, but in others, particularly in the UK, it remains common.

If robust clinical trials are not available, then expert opinion forms the next level in the evidence hierarchy. The papers presented here provide an analysis of the data on screening asymptomatic men for NSU, interpreted by experts who are familiar with the data and have considerable clinical experience. As you will see, they reach different conclusions. The purpose of presenting the arguments for and against in this forum are threefold. First, it draws together the available evidence and allows individual clinicians to make an informed choice about their own practice. Second, it clarifies the process that informed the decision not to recommend screening asymptomatic men for NSU in the recently published UK national screening and testing guidelines for STIs.¹ In this case the group commissioning the guidelines (clinical effectiveness group of the British Association for Sexual Health and HIV (BASHH)) reviewed the expert opinions and made a recommendation based on them. Third, it highlights the obvious gaps in our knowledge and indicates the need for further research. The main focus here needs to be on further defining the aetiology and pathogenesis of NSU, and on determining its long-term morbidity, especially regarding any effect on fertility in women.

The arguments for and against screening asymptomatic men for NSU are not clear-cut, but when an asymptomatic man walks into a clinic, clinicians have to make a decision, and not changing current practice is as active a choice as altering practice. The national guidelines and the information below should allow you to make the best choice for your patients based on what is currently known.