Best evidence topic reports (BETs) summarise the evidence pertaining to particular clinical questions. They are not systematic reviews, but rather contain the best (highest level) evidence that can be practically obtained by busy practising clinicians. The search strategies used to find the best evidence are reported in detail in order to allow clinicians to update searches whenever necessary. The BETs published below were first reported at the Critical Appraisal Journal Club at the Manchester Royal Infirmary¹ or placed on the BestBETs website. Each BET has been constructed in the four stages that have been described elsewhere.² The BETs shown here together with those published previously and those currently under construction can be seen at http://www.bestbets.org.³ Six BETs are included in this issue of the journal, the last two of which are negative.

• Abdominal radiography in “body packers”

• Use of heliox for acute asthma in the emergency department

• Cardiopulmonary bypass and the survival of patients in cardiac arrest

• Oral or intravenous thiamine in the emergency department

• Antibiotic prophylaxis for pretibial haematomas in the elderly population

• Prophylactic antibiotics for subungual hematoma