Mobile telephones are now almost universally owned by the adolescent section of the population in the United Kingdom. They offer teenagers individuality, sociability, rebellion, peer group bonding, and adult aspiration.¹ Such telephones, however, are known to be a potential source of electromagnetic interference that may affect the reliability of medical equipment.² Many hospitals in the United Kingdom, therefore, operate a ban on their use in clinical environments. The rationality of such blanket bans has been questioned by some, who argue that they should be limited to areas involved in intensive care, and that the potential benefits to patients and staff outweigh the minimal risk in low dependency or communal areas.³ It is certain, however, that warning signs, policies concerning the general use of mobile telephones, are frequently ignored in hospitals, perhaps especially so by teenagers.

Case report

We describe the observation of troublesome interference with a routine electrocardiogram recording in a 15-year-old girl undergoing evaluation in our outpatient department. The abnormal trace (Fig. 1) was inexplicable, and occurred repeatedly until it was discovered that the girl had a mobile telephone left on silent-mode in the pocket of her trousers. Once the telephone was turned off, we obtained at the first attempt a normal electrocardiogram (Fig. 2), free of any interference.

Figure 1. The recording of poor quality obtained whilst our patient had her mobile telephone switched on.

Figure 2. The normal electrocardiogram obtained immediately the patient had turned off her mobile telephone.