It is nearly two years since special teams were sent to patrol public hospital wards and monitor compliance with patient safety guidelines, following a spate of medical blunders. Health secretary Dr York Chow Yat-ngok said at the time this was because the mishaps involved repetition of the same kinds of mistakes in routine procedures. Special measures to maintain public confidence in the health system were justified, since lapses in everyday routines that result in injections being wrongly given and drugs being wrongly labelled can have serious or even tragic consequences for patients. It would be unrealistic to expect that human error could be reduced to zero, but reasonable to expect that the most basic requirements of patient safety are made as fail-safe as possible. That is clearly not so in the case of a woman transfused with the wrong blood type after surgery at Caritas Medical Centre in Sham Shui Po last week. A preliminary investigation shows that laboratory staff at Caritas apparently swapped her blood test result with that of another patient. As a result she was given the wrong blood, a mistake that can cause haemorrhage or clotting. It was when she was transferred to the neurosurgery unit at Kwong Wah Hospital after a brain haemorrhage that medical staff discovered her blood type was B, and not A as written in Caritas' records. Fortunately, the other patient did not require a blood transfusion. At the time blunders seemed a regular occurrence in the wards, one hospital chief put some of the incidents down to lack of teamwork and co-operation among frontline staff, shift handover procedures being one example. Such lack of communication can open the door to mistakes. Granted, the latest one occurred in a laboratory, not at the bedside. But there, too, teamwork and checking can avoid rudimentary and potentially dangerous human errors. An investigation by a panel of doctors, including external representatives ordered by the hospital, may show whether this was the case. That said, the issue of medical blunders needs to be put into perspective. When there appeared to be a rash of them a couple of years ago, this followed the implementation by the Hospital Authority of a policy of revealing incidents promptly, along with transparent action to identify and remedy defects in the system. A series of disclosures did not necessarily mean things were getting worse, although they did not seem to be getting any better at the time. Thankfully, however, not many have surfaced since. So openness and a more proactive response seem to have reinforced patient safety. It is good to see that it is being maintained and essential that it is for the sake of public confidence.