Removing a splinter from a finger can usually be quickly achieved with a pair of tweezers or a needle. But for Rexy Yeung Lok-sze, even a high-frequency electric current was not enough to get a speck of prawn shell out of her thumb; it left her with a painful and long-lasting injury. The current was applied by a doctor in a procedure known as electrocautery, which burns away soft tissue. In Yeung's case, it removed the tissue but not the sesame seed-sized piece of shell which another doctor removed 11 days later - with a needle. By that time the injury from the original treatment had developed an infection, which persisted for a year and left Yeung with a tender thumb but no visible scars. At a Medical Council disciplinary hearing yesterday, chairman Felice Lieh Mak said William Cheng Kin-keung had shown a high degree of recklessness in using electrocautery on Yeung. 'It is an invasive procedure which should only be resorted to where the patient's condition indicates,' she said. Not only did Cheng wound his patient unnecessarily, but he performed the procedure in the wrong place. The wound, as the second doctor found, was 'some distance' away from the site of the foreign object. Cheng, who did not appear, pleaded guilty through a lawyer to two counts of professional misconduct for inappropriate use of electrocautery and failure to perform it in the right place. He was removed from the general register for three months and ordered to take courses in the proper use of electrocautery and management of foreign bodies. The council heard that Yeung approached Cheng on April 18, 2008, three days after pricking her thumb on a prawn shell and experiencing persistent pain. After Cheng operated on her, the pain in her thumb remained, and her new wound began to bleed. On April 22, another doctor gave her antibiotics for the inflammation then removed the prawn shell a week later, using local anaesthetic and a fine needle. Electrocautery is designed to use a high frequency concentration of electricity to burn through unwanted tissue. As such, it does not easily target foreign objects lodged in the skin and removes a lot of the surrounding tissue, leading to a large wound and long recovery time.