Computed tomography colonography—or virtual colonoscopy—is gaining ground as a minimally invasive technique for visualising the colon and screening for early neoplasms. Unfortunately, the images of the colon are accompanied by images of the other abdominal organs, bones, blood vessels, and soft tissues. These unwanted data may irritate the clinician, who has no choice but to consider other diagnoses. A study of 75 patients in Denmark (Gut 2003;52: 1744-7)found that 49 had extracolonic abnormalities and 12% needed further investigation. Two patients needed surgery.

Until 1997 the Mayo Clinic's procedure for ordering blood for transfusion used handwritten identification of the patient by the clinician in addition to the standard paperwork. The clinicians then asked for the system to be changed to eliminate the handwritten form (Mayo Clinic Proceedings 2003;78: 1357-9). Within two years the risk of an error had risen from 1 per 10 000 to 6 per 10 000. The old system was reinstated, but not until 2001 did the error rate return to the old figure. The lesson, says the article, is to have an effective error identification system.

Scientists have successfully immunised mice against the Ebola virus. The vaccine involves virus-like particles made from Ebola's two …