Interim report: Retained swabs following invasive procedures - themes identified from a review of NHS serious incident reports

The Health Services Safety Investigations Body (HSSIB) is conducting an investigation into events involving retained swabs following invasive procedures. Swabs are sterile pieces of gauze which are used to absorb bodily fluids such as blood during an invasive procedure. An invasive procedure is ‘a procedure that is performed where a hole or incision is made or via a patient orifice and usually where a documented consent is required’ (Centre for Perioperative Care, 2023). A retained swab event is when a swab is unintentionally left inside a patient’s body after an invasive procedure.

To explore this issue, the investigation used a real patient safety incident involving a patient who had undergone heart surgery. Following their surgery, a chest X-ray identified that a surgical swab had been retained. The patient returned to the operating theatre and the swab was removed. Later, a chest X-ray identified another surgical swab in the same location within the patient’s chest. The patient went back to the operating theatre and the second swab was removed.

As part of the wider investigation, HSSIB analysed and identified common themes in 31 serious incident reports (investigation reports by local trusts into healthcare safety incidents) that had been conducted between September 2019 and September 2022, where a swab was unintentionally retained following an invasive procedure.

The investigation excluded serious incident report events related to retained vaginal swabs, which often occur in maternity settings. Although retained vaginal swabs are the most common foreign object to be unintentionally retained, the Healthcare Safety Investigation Branch (HSIB) has already investigated this type of event (Healthcare Safety investigation Branch, 2019).

This interim report presents the findings of the themes identified in the trust serious incidents reports. Some themes will be explored further as part of the investigation. The aim of this report is to share current understanding of where and how retained swab events occur, and to help healthcare organisations to take a proactive, systems-based approach to understanding and seeking to address this persistent patient safety concern.

Incidents involving the retention of a swab following an invasive procedure that were not intended to be retained are a sub-type of ‘retained foreign object post procedure’ and so are classed as ‘Never Events’. The NHS defines Never Events as ‘patient safety incidents that are wholly preventable where guidance or safety recommendations that provide strong systemic protective barriers are available at national level and have been implemented by healthcare providers’ (NHS Improvement, 2018).

Never Event data from NHS England (2022) shows that the number of retained swab incidents varies each year, occurring between 11 and 23 times a year since 2015 (see figure 1).

A report called ‘Opening the door to change’ (Care Quality Commission, 2018) stated that for some Never Events, the strength of the barriers (the controls put in place to prevent them) is variable and potentially not as strong as originally thought.

The Never Event data in figure 1 only shows part of the wider picture – that is, it only captures incidents that were identified, reported and investigated.

Figure 1 Number of retained surgical swab Never Events, 2015 to 2023

The serious incidents reports reviewed by the investigation included comments made by patients and families who had experienced a retained swab following an invasive procedure. They talked about feeling distressed, worried, anxious, feeling frightened by what had or could have happened to them, and having issues sleeping as a result.

‘This event has had a huge impact on me and my family. We have found it extremely upsetting and distressing. I have had to take time off work due to the anxiety I am experiencing.’

The most common impact on patients was that they had to have further surgery to retrieve the swab. The retained swab following an invasive procedure event meant that some patients had prolonged hospital stays and had to take extended time off work.

To understand the current themes and trends in retained swab serious incidents, HSSIB searched the Strategic Executive Information System, which is a national database for reporting serious safety incidents in healthcare. The search identified 59 serious incidents relating to retained swabs following an invasive procedure across 44 trusts between September 2019 and September 2022.

Attempts were made to contact all the trusts that had reported retained swab following an invasive procedure incidents and 31 relevant serious incident reports were made available to HSSIB.

The investigation analysed these reports using a recognised, structured approach (Braun and Clarke, 2006) to identify common themes and factors that contributed to the retained swab incidents.

The thematic analysis was based on trust serious incident investigation reports; the quality and depth of these investigations varied. Due to the nature of the incidents, some of the serious incident investigations were not able to identify exactly how and when the swab was unintentionally retained, and/or why it was not removed.

There was confusion about who was responsible for the reconciliation of items including surgical swabs. Evidence from the thematic analysis indicated that the view was that it was the scrub practitioner’s responsibility to reconcile the swabs and that the surgeon was responsible for ensuring all items that enter the surgical field (including swabs, instruments and any other ancillary items) are returned to the scrub practitioner to be counted. However, in some reports more emphasis seemed to be placed on the surgeon being responsible.

The HSSIB investigation is exploring the standards for the prevention of retained foreign objects (such as surgical instruments and swabs) and it is apparent that there was, and continues to be, a lack of clarity about where responsibility lies for the reconciliation of surgical swabs.

The ‘Standards and recommendations for safe perioperative practice’ state:

‘… although it is the responsibility of the operating surgeon to return all items, it is recognised that the perioperative practitioner is accountable for implementing a checking procedure in order to be able to state categorically to the operating surgeon that all items are accounted for and, on the final count, have been returned’ (Association for Perioperative Practice, 2022).

While the ‘National Safety Standards for Invasive Procedures’ (NatSSIPs) (NHS England, 2015) are not explicit about responsibilities, the revised version, NatSSIPs 2 (Centre for Perioperative Care, 2023), states that the prevention of retained foreign objects is a shared responsibility and that staff completing the swab count should be General Medical Council (GMC), General Dental Council (GDC), Nursing and Midwifery Council (NMC) or Health and Care Professions Council (HCPC) registered; any unregistered staff should be assessed as competent.

The Association for Perioperative Practice’s standards are applicable to operating theatre departments, whereas NatSSIPs 2 are applicable to all invasive procedures where swabs are used. These include procedures undertaken in operating theatres, labour suite rooms and emergency departments, interventional radiology hybrid procedures, pacemaker insertion, and where the procedure involves an open cavity in the patient’s body that is large enough to retain an instrument or swab.

The investigation will continue to explore the standards, responsibility and accountability for swab reconciliation. Therefore, HSSIB makes the following safety observation:

HSSIB makes the following safety observation

The position of a swab in a patient’s body meant that it may not always be in direct line of sight. In other instances, the scrub practitioner could not see where swabs were because the surgeon was standing in a position that blocked their view. Staff also commented that smaller swabs were more difficult to see.

Although not highlighted in the thematic analysis, the investigation is aware of another factor that can limit the visibility of swabs: when they absorb blood, the visual contrast with the surrounding tissue is reduced. This was identified as part of an investigation into the ‘Detection of retained vaginal swabs and tampons following childbirth’ (Healthcare Safety Investigation Branch, 2019). NatSSIPs (NHS England, 2015) states that ‘all swabs used for invasive procedures should contain radio opaque markers’ (markers that show up on an X-ray) as they can be used to detect retained swabs. NatSSIPs2 continues to endorse the use of radio opaque markers (Centre for Perioperative Care, 2023).

The radio opaque strip within a swab appears as lines on an X-ray (see figure 2). There can be many other similar looking lines depicting other items or features on an X-ray image. Therefore, the retained swab may not stand out to the person reviewing the X-ray. In addition, when attention is focused on one object or task, it can be at the expense of noticing and attending to other available information (Mack, 2003). This means that when an X-ray is performed for reasons other than detecting a retained swab, such as a suspected collapsed lung, the person reviewing it will be focused on looking for signs of a collapsed lung and may therefore miss something that indicates a swab. This type of occurrence was noted in another investigation into the placement of nasogastric tubes (Healthcare Safety Investigation Branch, 2020), where a misplaced nasogastric tube was not initially detected.

Figure 2 Chest X-ray showing one retained swab

The analysis of the serious incident reports identified that changes to the team during a procedure or that different teams were conducting the swab count were considered as contributory factors. When there is a change of team, NatSSIPs (NHS England, 2015) suggested that a swabs, sharps and instrument count should be conducted between the outgoing and on-coming scrub practitioners. On a few occasions, this count had not occurred. Reasons for the counts not being conducted included tension in working relationships between operating theatre staff, or seeing other colleagues conducting a count and feeling that their assistance was not required.

Reports discussed the risk caused by shift changes during invasive procedures and the impact this has on the continuity of staff and, in turn, the impact on tasks such as swab counting. NatSSIPs 2 (Centre for Perioperative Care, 2023) has made it more explicit that a count should be performed if there is a changeover of either the scrub practitioner or circulating practitioner.

In addition, the reports commented on challenges created because of limited numbers of staff being available on the day. Limited staffing meant the team skill mix for the day was not optimal, that there was not a scrub practitioner available for the count, or that staff were required to work a longer day to ensure there were enough staff to cover a procedure.

In some of the reports reviewed, the skin had been closed before the final swab count had been completed. The reports offer explanations for this, including a lack of clear communication between the surgical team and the scrub team, or where the surgeon perceived the final count was correct as they had been handed instruments for closure.

‘Sign Out’ (a checklist performed at the end of an invasive procedure) was also seen to be completed before the count was finalised. Reasons given for this included:

• to complete the case efficiently to enable the operating theatre to be made ready for the next patient
• the scrub practitioner and circulating nurse perceiving that they knew where all the swabs were and thought the count would (when conducted) be correct.

In some cases swabs were still being used while the count was being conducted. This was because the swab was required to absorb liquid or blood at the surgical site.

Retained swab events were most common during invasive procedures of the abdomen, such as a laparotomy (a surgical cut into the abdominal cavity). Retained swab events were also more common during colorectal (lower intestinal tract) invasive procedures and gynaecological invasive procedures.

Retained swabs events occurred in all lengths of invasive procedure but were most common in procedures that lasted more than 4 hours or procedures that were less than 1 hour in duration.

There was evidence in some reports of a culture of practice among consultant surgeons of leaving the operating theatre before a procedure was completed. Reports described how the consultant surgeon would perform most of the procedure but hand over to their surgical assistant or registrar (who had often been present for the procedure) to conduct the skin closure. The consultant surgeon would then leave the operating theatre to write up their surgical notes, continue their ward round or see their next patient.

This meant that the consultant surgeon was not present when the final swab count was completed, or for the World Health Organization (WHO) surgical safety checklist (World Health Organization, 2009) ‘Sign Out’, when it is confirmed that the swab, instrument and needle counts are complete.

Surgeons had also informed the scrub practitioner or anaesthetist that they had inserted a swab temporarily but subsequently left the operating theatre, leaving other members of the theatre team (for example a more junior surgeon) to complete the procedure.

Surgeons had been noted to take swabs and/or equipment directly from the scrub practitioner’s trolley without informing them. This had led to surgeons using swabs without the scrub practitioner being aware of this, sometimes after swab counts had been completed.

There was evidence throughout the serious incident reports that staff were distracted, interrupted or their attention was focused elsewhere. This was considered to negatively affect the swab count or staff’s ability to track swabs. Distractions and interruptions in the operating theatre environment included questions or requests from other staff members, the movement of other staff members, conversations, noise, and awareness that the end of the shift was approaching.

Those involved in the swab count could be required to conduct multiple tasks at the same time. Evidence indicates that some multi-tasking may be beneficial to performance. However, too much multi-tasking, especially when tasks are difficult, can be detrimental to performance (Adler and Benbunan-Fich, 2012).

Time pressure meant that tasks could be rushed or missed. Factors contributing to the perception of time pressure included awareness of other cases, including emergency procedures, that were waiting to come into the operating theatre, the surgeon needing to see other patients, a mismatch in the speed at which tasks were being completed between the surgical and scrub teams, and awareness that the shift was coming to an end or had ended.

Incidents were more common in procedures that finished in the afternoon and early evening, especially between 14:00 hours and 19:00 hours. Considering the length of the procedures and that retained swab events are more common in the afternoon and evening, it would be beneficial to consider whether fatigue was a contributory factor.

However, only one of the serious incident reports reviewed by the investigation considered fatigue. Without further data, it is difficult to draw conclusions from the information provided in the serious incident reports.

Previous Healthcare Safety Investigation Branch investigations have found fatigue to be a contributory factor in safety incidents, including ‘Detection of retained vaginal swabs and tampons following childbirth’ (Healthcare Safety Investigation Branch, 2019). Fatigue may be subject of future Health Services Safety Investigations Body investigations (Healthcare Safety investigation Branch, 2023).

Several reports cited that written policies and procedures may be unclear. This included:

• not specifying times at which counts are to be performed
• not specifying how counts should be recorded
• not stating that surgeons should verbalise when they place a swab into, or take one out of, a cavity.

Initial findings from this thematic analysis suggest that there are multiple factors that may contribute to the occurrence of a retained swab event and although they are categorised as Never Events under ‘retained foreign objects’ there are currently no ‘strong systemic barriers’ available to prevent them.

HSSIB makes the following safety recommendation