Every year, surgical swabs, instruments, and other items are left inside patients after operations in the NHS—a completely preventable error known as a "never event." This matters because the current system, which relies on staff manually counting equipment before, during, and after a procedure, is prone to mistakes. Even when the count is correct, items can still be retained. When a count is wrong, searching for the missing item can delay surgery and increase patient risk. Retained items cause complications, longer hospital stays, and often require a second invasive procedure to remove them. The research team will conduct a systematic review of all interventions designed to reduce retained items—such as electronic tagging, barcode scanning, or improved counting protocols—and assess their effectiveness and cost-effectiveness compared to standard practice. They will measure not only actual retained items but also near-misses and counting errors. If successful, this review will provide NHS hospitals with clear, evidence-based guidance on which methods best prevent these errors. The impact is direct: fewer patients harmed, fewer repeat surgeries, and reduced strain on operating theatre schedules. The findings could quietly improve patient safety across every surgical unit in the country.
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Unintentional retention of items after an invasive procedure is one of the most common ‘Never events’ to occur in the NHS – events considered to be completely preventable because national guidance or safety recommendations provide strong protective barriers and should have been implemented by all healthcare providers. Standard methods to avoid retention of items involve counting of equipment before, during, and after a procedure, to ensure that all items are accounted for. However, this system is prone to error, and many retained items are found to have occurred despite the count being correct. Even when an incorrect count highlights the presence of a missing item before the end of the procedure, the time required to locate the item may lead to additional risks for the patient, as well as consequences for others, such as delays to the operating list. The impact of retained items on patients is considerable, including risks of perioperative complications and increased length of hospital stay. Retained items may also be discovered after the patient has left hospital, necessitating re-admission and a further invasive procedure to remove the item. We will conduct a systematic review to identify methods that may be used to reduce the risk of retained items and assess their efficacy and cost-effectiveness. We will include any intervention intended to reduce the occurrence of retained items, that is compared to standard methods used to count items. Our primary outcome is the occurrence of retained items; secondary outcomes include the occurrence of ‘near-miss’ events, frequency of counting errors, and adverse events related to the intervention. We will assess risk of bias for data included in the synthesis, and use the GRADE approach to assess the certainty of the evidence.
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