A nurse wearing scrubs prepares surgical instruments including swabs.

Risk of surgical swabs being left inside patients

16 April 2024

We've investigated the risk of unintentional ‘retained’ swabs after invasive procedures. The investigation was launched after we examined the case of a patient who had two swabs left in her chest following serious heart surgery.

When operating on a patient, a surgeon may put swabs into the patient’s body to absorb bodily fluids such as blood. The operating theatre team count the swabs in and out, using a process known as reconciliation. This is to ensure all swabs are accounted for at the end of the operation. Our report examines what influences the reliability of the swab count and how achievable the overall reconciliation process is.

Retained swabs are classed as Never Events. However, data shows that there has been between 11 and 23 retained swab incidents a year since 2015. We suggest in our report that whilst the counting of swabs may be ‘largely successful’ in preventing these types of incidents, it does not provide a ‘strong systemic barrier’ to error.

Helen’s story

This is shown in the case set out in our report. Helen, 59, underwent a procedure to treat coronary artery disease. It took approximately 5 hours to complete and involved opening her chest to expose her heart.

Following the procedure, a chest X-ray identified that a swab had been left inside her chest. The wound had to be opened again so that the swab could be removed. After this procedure, another chest X-ray showed a second swab remained in her chest and she returned to the operating theatre, her third time in total.

Complex factors

Helen’s case and our wider investigation, which involved interviews and a focus group with NHS operating theatre staff and observations at an NHS Trust, showed there are many complex factors which influence the reliability of a swab count and achievability of the overall reconciliation process.

This includes:

  • the design of swabs (for example, the swab becomes difficult to see once inside a patient)
  • the environment (for example, the theatre environment can be noisy and busy)
  • organisational factors
  • pressures (for example, waiting list pressures means there is an emphasis on increasing throughput in theatres, adding time pressures on staff)
  • how the task interacts with others that are going on at the same time (for example, staff are counting potentially hundreds of other surgical items whilst also preparing the equipment the surgeon needs).

We highlight that the reconciliation process has not been formally analysed or designed using human factors expertise (where the interactions between people and other elements of the system in which they work are explored) or any other process design expertise.

Inappropriate blame

HSSIB also identified that Trust serious incident investigations tend not to explore the various factors in depth and tend to focus on the actions of staff.

In an interim report published in December, we analysed 31 serious incident reports focused on retained swab events. We drew out common characteristics in those incidents, ranging from the type and duration of surgery, to the responsibility for swab counts and competing pressures.

The report emphasises that blame can be inappropriately placed on scrub practitioners and/or the surgeon when an item goes missing, rather than the reconciliation process being seen as a team activity and one that can be influenced by a wide range of interrelating factors. Therefore, recommendations made in serious incident reports are often focused on further training or reminding staff to follow procedure without fully understanding why the process might not be effective.

The investigation found that the current design of swabs does not help staff to locate, identify or track them during the reconciliation process. There are tools and technology that could be used to improve the accuracy of the swab count. However, the investigation emphasises that these are not embedded in healthcare in the UK.

Our report refers to how other safety critical industries manage risk, where they assess whether a risk has been reduced to ‘as low as reasonably practicable’ (ALARP). It involves balancing the risk with other safety priorities, costs, benefits, productivity, and efficiency. We highlight that the concept of ALARP could help with understanding and planning for risk, as well as assessing possible mitigations like tools and technology and what their impact could be.

Safety recommendations

Our report concludes with three safety recommendations:

  • One is focused on reviewing and amending the process and standards for the reconciliation of swabs, using human factors expertise and user-centred design.
  • The second safety recommendation is focused on developing a framework to assess whether healthcare risks, such as retained swabs, are acceptable, tolerable and have been reduced to as low as reasonably practicable.
  • The third is to conduct research to assess the priority and feasibility of implementing technology that could support reducing the risk of retained swabs.
Saskia Fursland
Saskia Fursland, Senior Safety Investigator at HSSIB.

Investigator’s view

Saskia Fursland, Senior Safety Investigator at HSSIB, says: “Retained swabs, as with any retained foreign object after surgery, can lead to physical and psychological harm for patients. When we spoke to Helen six months after her incident, she was still visibly upset and struggling with the psychological effects.

"Whilst the number of retained swabs appear relatively low, they continue to occur and there has been up to 23 patients in a year experiencing an incident and the negative patient outcomes that can come with it – from distress and trauma, the risk of infection, to further surgery and prolonged hospital stays.

“What we have called for in our report is for those working in healthcare to think differently about the issue and apply a view of the whole system that underpins the process – examine all the factors that influence the swab counting rather than just focusing on individual actions or behaviours.

"We have also reinforced that the healthcare system must continue to look at how they assess and manage risks and maintain the right balance between safety, and other priorities such as financial costs, productivity, and efficiency.

"The recommendations we have made are aimed at influencing safety improvements, not just for swabs but any item used in surgical procedures, and at encouraging a different approach that could lead to sustained change.”

Read the report

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