Retained swabs following invasive procedures

1.1.1 This investigation focuses on exploring the patient safety risk of retained swabs following invasive procedures. An invasive procedure is ‘a procedure that is performed where a hole or incision is made or access is via a patient orifice and usually where a documented consent is required’ (Centre for Perioperative Care, 2023). Swabs are described in more detail in section 1.2.

1.1.2 The report refers to unintended retention of swabs, which means incidents where a swab is unintentionally left inside a patient's body. This investigation acknowledges there are times swabs may be intentionally left inside the patient. This is outside the scope of this investigation.

1.1.3 Retained swab incidents can result in negative patient outcomes including distress to the patient, further surgery, prolonged hospital stays and extended time off work, as described in this investigation’s interim report which was published in December 2023 (Health Services Safety Investigations Body, 2023). There is also a risk of infection and death (Primiano et al, 2020). To explore the issue of retained swabs, the investigation used a real patient safety incident involving a patient who had undergone heart surgery. This incident, referred to as the reference event, is described in section 2 of this report.

1.1.4 This report builds on the findings described in the interim report (Health Services Safety Investigations Body, 2023). The interim report describes the common themes from 31 serious incident reports (investigation reports by local trusts into healthcare safety incidents), where a swab was unintentionally retained following an invasive procedure.

1.1.5 This investigation has not focused on 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 (NHS England, 2023), the Healthcare Safety Investigation Branch (HSIB) has already investigated the detection of retained vaginal swabs and tampons following childbirth (Healthcare Safety Investigation Branch, 2019). However, the findings from this investigation may be applicable to maternity and other areas of care.

1.2.1 Swabs are pieces of gauze which are used to absorb bodily fluids such as blood during an invasive procedure. There are many types, varieties, shapes and sizes of swab which can be used during an invasive procedure. The Trust where the reference event took place used three types of swab during a coronary artery bypass graft (CABG) procedure (the type of heart surgery the patient underwent):

• 22.5 cm x 22.5 cm swabs with tails (see figure 1)
• 15 cm x 10 cm swabs
• 45 cm x 45 cm swabs with tails.

1.2.2 Swabs were typically packed in bundles of 5 with a red tie cord (see figure 2) and each swab contained a strip that can be detected on an X-ray.

1.3.1 Incidents involving the unintended retention of a swab following an invasive procedure 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). The type of incident explored in this report falls within the Never Event category of ‘retained foreign object post procedure’.

1.3.2 Never Event data from NHS England (2023) shows that since 2015 the number of retained surgical swab incidents reported each year has varied between 11 and 23 (see figure 3).

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

1.3.4 The Never Event data in figure 3 only shows part of the wider picture – that is, it only captures incidents that were identified, reported and investigated.

1.3.5 HSSIB’s interim report (Health Services Safety Investigations Body, 2023a) recommended that retained swab incidents should no longer be classed as Never Events because there are no ‘strong systemic barriers’ (tools, technology, organisation, task, environment, and people) in place to prevent them. On 5 February 2024, NHS England launched a consultation on the existing Never Event’s framework. The consultation is being held following the findings of reports from the Care Quality Commission and HSIB that highlighted for several types and sub-types of Never Events the barriers are not strong enough to make an incident wholly preventable.

1.4.1 The process that is currently used to prevent the unintended retention of a swab following an invasive procedure is to count the swabs that enter and exit the procedural field (the sterile area where the surgeon is operating). The Standards and Recommendations for Safe Perioperative Practice (referred to as AfPP Standards in this report) (Association for Perioperative Practice, 2022) and National Safety Standards for Invasive Procedures 2 (NatSSIPs 2) (Centre for Perioperative Care, 2023) outline how and when items used during an invasive procedure, including swabs, sharps (such as scalpel blades), disposable items and instruments and their constituent parts, should be counted.

1.4.2 The AfPP Standards apply to operating theatre departments, whereas NatSSIPs 2 apply to all invasive procedures where swabs are used, for example operating theatres, labour suite rooms, interventional radiology (procedures using image-guidance), pacemaker insertion or the emergency department, and where there is an open cavity in the patient’s body large enough to retain them.

1.4.3 NatSSIPS 2 states the count should be performed by two trained staff, with at least one being registered with the General Medical Council, General Dental Council, Nursing and Midwifery Council (NMC) or the Health and Care Professions Council.

1.4.4 Registered Nursing Associates (RNA) are registered with the NMC but would be supervised in the procedural/surgical environment by a registered nurse or operating department practitioner (Perioperative Care Collaborative, 2021).

1.4.5 NatSSIPs 2 (Centre for Perioperative Care, 2023) details that a swab count should be conducted before starting the procedure. A count should then be performed (as appropriate to the procedure):

• before the closure of a cavity or major organs
• before the first layer of muscle is closed
• before wound closure begins.

1.4.6 A final count should take place at the beginning of closure of the patient’s skin or before the end of the procedure. A count board must be used throughout to document and keep track of the count (Centre for Perioperative Care, 2023). A count board is a large whiteboard that is usually mounted to a wall in the operating theatre but can be mobile, which is visible to the theatre team.

1.5.1 The World Health Organization (WHO) developed the original surgical safety checklist in 2009 to improve team communication and consistency of care, and therefore reduce complications and deaths associated with surgery (Haynes et al, 2009).

1.5.2 The WHO checklist (World Health Organization, n.d.) is a 19-item checklist which lists a range of tasks and prompts, each specifically designed to address known safety risks. The checklist is intended to be applicable to all environments and types of surgery.

1.5.3 The checklist is used at three points during a patient’s operative pathway:

• Sign In: Completed when the patient arrives in the operating department (usually in the anaesthetic room, or operating theatre if an anaesthetic room is not used) to ensure that the indicated procedure is being carried out on the correct patient.
• Time Out: Following the induction of anaesthetic but before an incision is made in the patient’s skin, again to ensure that it is the correct patient and that the indicated procedure is being carried out in the correct location (for example, left or right side of the body).
• Sign Out: Completed at the end of the procedure before the patient leaves the operating theatre. The Sign Out process includes aspects of safety within the care pathway including confirmation that the swab and instrument count is correct.

1.5.4 The WHO surgical safety checklist has been built upon with ‘The NatSSIPs Eight’ (Centre for Perioperative Care, 2023) which outlines the sequential steps as follows:

1. consent, procedural verification, and site marking
2. team brief
3. sign in
4. time out
5. safe and efficient use of implant (where relevant)
6. reconciliation (counting) of items to prevent retained foreign objects
7. sign out
8. debrief/handover.

1.6.1 The operating theatre and intensive care multidisciplinary team members involved in the reference event are referred to by their job titles in this report. Their roles and responsibilities are outlined in table 1.

1.6.2 ‘Surgeons’ are referred to throughout this report; however, it should be noted that the report’s findings can be applied more widely to any ‘operator’ carrying out an invasive procedure (as referred to by NatSSIPs) (Centre for Perioperative Care, 2023).

3.1.1 The interim report published by this investigation highlighted the commonly identified vulnerabilities with the swab reconciliation process (Health Services Safety Investigations Body, 2023a). The factors highlighted in this section are additional findings that are relevant to Helen’s case, but that could also apply to other retained foreign object incidents.

3.1.2 It should be noted that there are many other potential factors not described in this section of the report that could have contributed to two swabs being unintentionally retained in Helen’s chest. However, limitations in the evidence available meant the investigation could not conclude whether these played a part or not.

Complexity of process

3.1.3 To understand the overall count process and the steps involved, the investigation produced a hierarchical task analysis (PDF) of the swab reconciliation process in cardiac operating theatres at the reference event Trust. The hierarchical task analysis (HTA) shows the overall process for swab reconciliation (how swabs are counted out and in) and breaks it down into a hierarchy of key goals, sub-goals, actions, and plans. More detailed information about how the HTA was produced can be found in the appendix.

3.1.4 The HTA indicates that the process for the reconciliation of swabs has many steps and complexities, and can vary depending on the situation. However, the HTA only visually represents part of the overall picture. The task is more complex than shown as many of the steps were repeated multiple times during the procedure. For example, typically during a CABG procedure three full counts of all swabs, sharps (e.g. needles) and instruments are conducted. However, there could be fewer or more full counts depending on the type of invasive procedure.

3.1.5 Three key staff roles are described in the HTA including the two staff members usually involved in counting the swabs:

• scrub practitioner (who is responsible for managing the count of swabs and instruments throughout the procedure)
• circulating practitioner (who would retrieve extra equipment and swabs as required during the procedure).

The surgeon also had a key role in that they were using the swabs and would need to communicate their actions with the scrub practitioner. It should be noted that the wider operating theatre team would also have an influence on the count process in supporting its success, but the wider team roles are not detailed in the HTA, for example, being quiet for the counts and minimising distractions.

3.1.6 The scrub practitioner and circulating practitioner were involved in the counts of other items such as instruments, needles, blades, ligation clips (used to tie a blood vessel or other tube in a patient’s body), and various other items that have the potential to be retained. The process for counting each item and documenting on the count board and within paperwork varied slightly depending on the item being counted.

3.1.7 It was reported to the investigation by multiple scrub practitioners that they also had to concentrate on the tasks being carried out by surgeons and to plan and prepare items that were required for the subsequent tasks in the procedure. Scrub practitioners described that it could get very busy and that it could be hard to concentrate on what was going in and out of the surgical site when they were also required to pay attention to other tasks.

3.1.8 The surgeon was also expected to attend to multiple concurrent tasks, as well as the swab reconciliation process. These included doing the surgery, co-ordinating the rest of the surgical team, and maintaining good communication with the perfusion team staff, who operate the heart-lung bypass machine.

Number of items to be counted

3.1.9 The investigation considered the number of items that needed to be counted. Staff reported that for a CABG procedure, they would prepare 35 swabs before surgery as follows (see table 2):

3.1.10 Staff reported that throughout the surgery more swabs would be added to the procedural field (the sterile area where the surgeon is operating) and that used swabs would be removed, all counted in bundles of five swabs of the same size. Staff reported that up to 100 swabs could be used. The number of swabs used is not documented in patients’ medical records, so it was unclear how many swabs were used in Helen’s case. The investigation observed a similar operation and noted 45 swabs being used.

3.1.11 The scrub practitioner and circulating practitioner were counting and tracking multiple other items. The Trust’s checklist of all the instrument trays that were opened as standard and must be accounted for during a procedure included 235 different items. A scrub practitioner told the investigation there could also be up to 200 needles to account for in some procedures.

3.1.12 The cardiac operating theatre was reported by theatre staff to be intense and busy. The investigation was told that procedures were “very time orientated”, where there were critical stages that needed to be completed in a timely manner to optimise the outcomes for the patient. One scrub practitioner reported that they conducted their task in a controlled manner but at speed.

3.1.13 The investigation considered that the complexity and the workload associated with counting swabs, sharps and instruments, combined with carrying out other tasks, was high. Factoring in other variables such as distractions and interruptions, competing tasks and time pressure (Healthcare Safety Investigation Branch, 2023a) it is evident that the current process presents challenges to accurately accounting for all surgical items, including swabs. With a person(s) at the centre of the counting process, a rate of error would be anticipated given the current process and context in which it is being applied.

Location of swabs during counts

3.1.14 The National Safety Standards for Invasive Procedures (NatSSIPS) (Centre for Perioperative Care, 2023) outline which procedures should include a ‘full count’. This includes major procedures (other than interventional radiology), all maternity procedures and any procedure where a cavity in a patient’s body is entered. NatSSIPS defines that the count should include any item entering the procedural field, including swabs, sharps, disposable items, instruments and their constituent parts.

3.1.15 The investigation observed a CABG procedure and noted that at quieter times during the procedure, the scrub practitioner removed used swabs from the procedural field. This practice was done to limit the number of swabs in the procedural field. The used swabs were counted into bags of five swabs and crossed off the count board.

3.1.16 The investigation observed that once the swabs had been placed into the bag, it was difficult to see how many swabs the bag contained. According to staff and the Trust’s policy, the swabs inside the bags were not counted or verified again during or after the procedure unless a discrepancy in the count was detected. Staff reported that it would be time consuming to count every swab in the operating theatre each time for the full count as they would have to open and go through all the bags. Therefore, the accuracy of the final swab count depended on every intervening used swab removal count being correct. If an error in the count coincided with an unintended swab retention, this would not be identified during the swab count.

3.1.17 When staff were conducting a count before the closure of each cavity, the investigation observed that the swabs were not located all in one place. Clean swabs were stacked in three piles in different locations on the instrument trollies, some swabs were on top of the patient, some were being used by the surgeons, and used swabs were placed into different collection bowls (depending on their size) on the instrument trollies. It was also reported and observed that used swabs that were particularly soiled may be placed into a bag and kept at the base of a trolley outside of the procedural field, until more swabs could be added to make up a bag of five.

3.1.18 The investigation observed that to count swabs that were in use, they would search around the procedural field locating and counting the swabs while leaving them in place (in situ). The scrub practitioner would also point to swabs or verbally confirm that a swab was being used by the surgeon and included this swab in their count. This meant the swab could subsequently be retained without detection as the count was ‘correct’. The different and moving locations for where the swabs and other items were and the number of items the scrub nurse had to count (see 3.1.9 to 3.1.11), also meant there was a risk a swab could be accidentally counted multiple times if the scrub practitioner and circulating practitioner did not realise it had already been counted.

Responsibility for swab reconciliation

3.1.19 The HTA (see figure 4) shows that there are three key staff roles involved in the swab reconciliation process; the scrub practitioner, the circulating practitioner and the surgeon. All three staff roles are fundamental to the success of the swab reconciliation process. According to the Trust’s swab, instruments and sharps policy:

‘The overall responsibility for ensuring the counts are correct at each stage and at the end of the procedure lies with the lead operating surgeon. It is the responsibility of the operating surgeon and scrub practitioner to ensure all items are accounted for. The count must be conducted by the scrub practitioner and the circulating practitioner.’

3.1.20 The investigation found that within the Trust’s policy there were varying descriptions of the responsibilities for the reconciliation of swabs, instruments and sharps, which may create confusion. The potential for confusion was also highlighted in the interim report (Health Services Safety Investigations Body, 2023a).

3.1.21 The investigation sought to understand further how responsibility for the reconciliation process worked in practice at the reference event Trust. The consultant cardiac surgeon reported that they were not involved in the count process, other than verbally checking before closing the patient’s chest that the swab count was correct. The surgeon stated that their assurance that the count was correct was reliant on the scrub team and that it was important to trust the team.

3.2.1 The risk of unintended swab retention arises from situations where swabs are placed into a cavity in a patient’s body. This can happen many times during a procedure. The count process and the documentation of swabs inside a cavity on the count board was designed to reduce the likelihood of a swab accidentally being left inside a patient. The investigation sought to understand the factors that influenced this key part of the process.

Surgical technique used

3.2.2 As part of the CABG procedure, grafts are obtained from the patient, usually from a vein in the leg and an artery that runs downwards inside the ribcage and close to the sternum (chest bone). Analysis of Helen’s chest X-ray showed the two swabs were located together within the mid-left zone of the chest.

3.2.3 The consultant cardiac surgeon told the investigation that when undertaking the CABG, they would roll up two 22.5 cm x 22.5 cm swabs “like little sausages” and put them into the patient’s chest. The rolled up swabs would act as a buffer between the chest and the lungs, keeping the lungs down and making preparation of the graft easier. An operating theatre staff member reported that some other surgeons would also use this technique but that it was not consistent practice. The method used would depend on how the surgeon was trained.

3.2.4 The location of the swabs in Helen’s chest meant they were obscured from view and so there was limited visual information to remind the operating theatre team that two swabs were there.

Communication and documenting on the count board

3.2.5 The Trust’s policy for the use of swabs, instruments and sharps in the operating theatre and for maternity procedures, stated that:

‘… any swabs placed inside a cavity or orifice during surgery must be recorded on the swab board. When the swab is removed it must be cancelled off the board with a single strike. It is the surgeon’s responsibility to provide verbal confirmation of any such items placed and subsequently removed.’

3.2.6 At the time of the reference event, the Trust did not have a designated space on the board for documenting the type of swab and its location when it was left inside the cavity. Since the reference event, the count board in cardiac operating theatres has been updated.

3.2.7 The investigation found that since the reference event, the communication and documentation of swabs being put into and later removed from a patient’s chest cavity was not always consistent.

3.2.8 Staff at the refence event trust reported that one of the difficulties in carrying out this process was the way in which swabs are used in cardiac surgery and that it was not possible to document or verbalise every swab that entered a patient’s chest cavity. Staff reported that most swabs used in cardiac surgery are used inside the cavity, but that the amount of time they remained within the cavity could vary. Swabs that went into the cavity and remained there for ‘a length of time’ were referred to as a ‘pack’. However, there was not a clear definition or understanding among staff or in the Trust’s policy of what a ‘pack’ was and the amount of time it would have to remain to be considered a pack. Staff reported that swabs were being packed and unpacked all the time and that it would take a large proportion of people’s concentration and energy to track every single swab entering and exiting the cavity.

3.2.9 The noise level within the operating theatre was identified as a factor that could impede communication of key information. The operating theatre where Helen’s CABG took place had a laminar flow system – a ventilation system designed to reduce airborne bacteria and therefore lower the risk of patients getting an infection after a procedure. It was reported by staff and observed by the investigation that the laminar flow system was noisy, making it difficult to hear conversations within the operating theatre. This placed a greater reliance on the communication chain between the surgeon, scrub practitioner and circulating practitioner for key information (such as a swab entering a cavity) to be passed on.

3.2.10 Several other factors were identified that could influence the communication between staff throughout the count process. These included the theatre layout, wearing of masks, accents, language barriers, workload, focus on other safety-critical tasks, distractions, hierarchy gradients between staff, and team relationships (see section 4.2 for further exploration of multidisciplinary team working). Some of these factors were also identified and described in the interim report (Health Services Safety Investigations Body, 2023a).

Check for retained items by the surgeon

3.2.11 According to the Association for Perioperative Practice (AfPP) Standards (Association for Perioperative Practice, 2022) and the NatSSIPS that were in place at the time of the reference event, ‘Operators should check the wound carefully for foreign objects before closure’ (NHS England, 2015). The investigation found the following challenges to achieving this task:

Visibility of swabs

3.2.12 The 22.5 cm x 22.5 cm and 45 cm x 45 cm swabs both came with ‘tails’. The swab tail is draped outside the patient’s body to make it easier to remove at the end of a procedure (Surgical Dressing Manufacturers Association, 2021).

3.2.13 The investigation was told, and observed, that the tails of the swabs were cut off before the swabs were used. NatSSIPS (NHS England, 2015), which applied at the time of the reference event, did not provide guidance on cutting swabs. However, the Association for Perioperative Practice (AfPP) standards stated that items should not be cut or altered and if altered documented in the patient’s records, highlighted on the count board and included in the count. The practice of cutting the tails was endorsed by the Trust’s swab and instrument policy. Staff reported that the tails of the swabs were removed because they could get caught, which could be catastrophic if they pulled on a vessel within a patient’s chest cavity.

3.2.14 The removal of the tails meant there were limited external visual cues to indicate that there was a swab inside a patient’s chest cavity. Through discussions with other specialties, the investigation found that this practice and perceived risk was not unique to cardiac surgery.

3.2.15 NatSSIPs (NHS England, 2015) has been updated since this reference event and states the swabs should ‘NEVER’ be cut (Centre for Perioperative Care, 2023). However, during a follow-up visit to the reference event Trust, staff told the investigation that it was not possible to buy the swabs without tails. This was because only a few specialties required the swab without the tail, and it was not cost-effective to procure swabs specifically for these specialties. This is an example of a wider system that is influencing operating theatre staff to not adhere to policy, and how local and national policies are not always achievable in practice.

3.2.16 During observation of two surgical procedures, the investigation noted that the absorbent material used in swabs turns red when in contact with significant bleeding and can look like human tissue, making them difficult to see. Staff also told the investigation that swabs can get very small, condensed, and be difficult to open when they have absorbed blood. In addition, the consultant cardiac surgeon reported that when a swab goes into a patient’s chest, it could be difficult to spot (see figure 4).

3.2.17 The detectability of swabs was also identified as a factor in HSIB’s investigation report on the detection of retained vaginal swabs and tampons following childbirth (Healthcare Safety Investigation Branch, 2019). The removal of the tails as a visual cue further compounds the issue of swab detectability.

3.2.18 Swabs could also be very deep within a patient’s chest and potentially obscured from view by their organs, such as their heart and lungs.

3.2.19 Overall, the investigation found that the design of swabs does not help the reconciliation process. The design of the swab does not help staff to track swabs within the operating theatre, locate them inside the patient, identify what type they are (without holding them up) or which pack they came from, or distinguish them from others of the same type; one swab looks very much like another. The limitations in the design of swabs are likely to directly contribute to a retained swab incident.

HSSIB makes the following safety observations

Searching the cavity by touch

3.2.20 As noted earlier, NatSSIPS (2015) and the AfPP Standards (Association for Perioperative Practice, 2022) state that the surgeon should carefully check the patient’s wound before closing it. The consultant cardiac surgeon who was involved in the reference event reported that it was possible to feel for a swab within a patient’s chest. However, in doing this there was a risk of harming the patient:

• putting their hand next to the patient’s heart created a risk of accidentally pulling out a graft when removing their hand
• there was a risk of inducing cardiac arrest (the patient’s heart stopping) by lifting the heart to check for a swab underneath.

3.2.21 In addition, the process for extensively searching the chest involves stopping ventilation for approximately 1 minute so that the patient’s lungs deflate, allowing better access to and visibility of the chest cavity. This process is not possible in all surgery cases as it depends on the stability and clinical condition of the patient. The cardiac consultant said that they would need to be sure an item was missing before doing such a search.

3.2.22 In Helen’s case the swab count was deemed to be correct and so an extensive search of the chest following the initial CABG procedure was not conducted.

Using X-ray to detect retained items

3.2.23 Each swab contained within it a strip that could be detected by X-ray. However, it was not standard practice to X-ray patients while in the operating theatre to check for retained foreign objects. Staff reported that exposing patients to X-rays was a risk and so they would only carry out an X-ray if they thought an item was missing.

3.2.24 As such, the X-ray detectable strip only offered a recovery mechanism for retained swabs and did not provide mitigation to prevent swabs being retained in the first place.

3.3.1 In Helen’s case, two chest X-rays were carried out and reviewed following her initial procedure. It was during the review of the second chest X-ray that a potential foreign object was detected. The investigation considered why a potential foreign object was not detected in the review of the first X-ray, in which it also appeared.

3.3.2 The investigation observed that there were many other items, tubes and lines visible on the X-ray and that a retained swab can look similar to other features on a chest X-ray, making them more difficult to detect.

3.3.3 From Helen’s medical records, it appears that both the trainee advanced clinical practitioner and the doctor who reviewed the X-ray were focused on clinical theories for Helen’s deterioration – that is, they were looking for signs of a collapsed lung. 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). Similar occurrences were identified in the thematic analysis of serious incident reports, as described in the interim report (Health Services Safety Investigations Body, 2023a).

3.3.4 Following its analysis of the chest X-rays the investigation found that without the benefit of hindsight, it was difficult to detect that there were two swabs in Helen’s chest (see figure 5). The two swabs were in the same position and looked like one shape. Figure 6 shows the retained swab that remained after Helen’s second surgery and was removed during her third procedure.

3.4.1 When Helen went back into surgery following her CABG procedure, staff perceived that there was only one swab to retrieve. Helen’s clinical condition was reported to be unstable during this re-opening procedure. The surgeon deemed it was unsafe to conduct an extensive search of Helen’s chest cavity and carry out a chest X-ray to ensure there were no remaining foreign objects.

3.4.2 The surgeon reported to the investigation that their priority was to close Helen’s wound, stabilise her and return her to intensive care. Therefore, the second swab was not detected until a further X-ray was conducted.

4.1.1 The low frequency of patient safety incidents involving retained foreign objects, including swabs (see figure 3 and figure 9), indicates that the counting of items is largely successful and that standards such as NatSSIPs (Centre for Perioperative Care, 2023) and ‘Standards and Recommendations for Safe Perioperative Practice’ (Association for Perioperative Practice 2022) can help reduce the number of retained swab incidents. However, counting items is not a strong systemic barrier and retained swab events can still occur. The investigation found there are many factors associated with the design of the reconciliation process, combined with complex interrelated system (tools, technology, organisation, task, environment, and people) factors, that routinely influence the reliability of the swab count and the achievability of the overall reconciliation process.

4.1.2 Staff told the investigation they were continuously having to make decisions and trade-offs to balance safety risks whilst also trying to maintain productivity and efficiency, which then influenced their actions. For example, many of the staff and national organisations the investigation spoke with discussed the significant pressure on trusts and staff to increase the throughput. However, safety procedures such as the swab reconciliation process were reported to take time and one stakeholder told the investigation there had been a loss of productivity due to safety processes; meaning fewer patients could undergo surgery each day.

4.1.3 There was a perception that retained swab events were “rare” and that this perception influenced staff decisions and actions. One surgeon stated that:

“I'm less worried about the swabs in the sense that how many operations happen every day and we get the swab count right? How many operations happen where we don't get it right there? In the grand scheme of things, it's a tiny, tiny, tiny percentage, isn't it?.”

4.1.4 The need to balance the competing priorities of safety risks with other priorities is noted in NatSSIPs. It states that ‘The need to prevent the rare occurrence of unintentional retention of items must be balanced against the need to support timely and efficient surgery and other procedures’ (Centre for Perioperative Care, 2023). The need to balance of safety with other priorities such as financial costs, time, loss of productivity, supervision, and maintenance is also reflected in safety science literature and is discussed further in section 4.3.

4.1.5 The investigation’s interim report highlighted a tendency to focus on human error in trust investigations of retained swab events (Health Services Safety Investigations Body, 2023a). However, there is limited understanding of the trade-offs that staff are having to make to balance cost, quality, efficiency and safety, and the influence of wider system (e.g. organisational) decisions and trade-offs. According to Read et al (2021):

‘Frontline workers generally operate under rules and procedures which provide a normative standard against which their behaviour can be judged. In contrast, designers, managers, and such generally operate with more degrees of freedom. It is easier to understand their decisions as involving trade-offs between competing demands, such as a manager unable to employ additional staff due to budgetary constraints or a designer forfeiting functionality to maximise usability. In many ways the copious rules and procedures that we place on frontline workers to constrain their behaviours masks our ability to see their decisions and actions as involving the same sorts of trade-offs (e.g. between cost and quality, efficiency and safety), and helps to reinforce the focus on human error.’

Development of reconciliation process

4.1.6 As noted in paragraph 4.1.1, the process of counting of items may be largely successful in preventing the unintended retention of swabs and other items used during a procedure. Evidence gathered by the investigation also indicates that the current process outlined in NatSSIPs (Centre for Perioperative Care, 2023) and ‘Standards and Recommendations for Safe Perioperative Practice’ (Association for Perioperative Practice 2022) may further reduce retained swabs incidents. However, the process and standards cannot consistently be achieved due to the complexities of the process, the complex context in which it is applied and due to the way in which people naturally think and process information.

4.1.7 The investigation has spoken with stakeholders who developed NatSSIPs (2015) and its latest iteration, NatSSIPs2 (Centre for Perioperative Care, 2023). The investigation was told that the process for reconciliation has evolved over the years based on what is considered by organisations to be good practice and clinical expert opinion. However, no one the investigation spoke with was aware whether the process had been formally analysed, designed or tested using human factors (which examines the interactions between people and other elements of the system in which they work) expertise or any other process design expertise.

4.1.8 The investigation noted there is scope to further review the current reconciliation process to understand it’s vulnerabilities to understand the underlying factors that contribute to the procedure not being followed. Human factors analysis methods and concepts could be used to explore the task itself, how the process interacts with other tasks, how people process information, and consider other system issues and pressures. This would help identify refinements that could be made to strengthen the process and improve its implementation.

4.1.9 The investigation was told that the team who developed NatSSIPs (Centre for Perioperative Care, 2023), and the Association for Perioperative Practice worked closely to ensure both standards aligned. Therefore, any further refinement to the standards would require both organisations to continue this unified approach. The investigation also recognises that the Centre for Perioperative Care and the Association for Perioperative Practice are membership organisations who rely on voluntary work to support their goals and need other organisations for implementation [bold text is the amendment to the original report published].

Understanding of team roles and responsibilities

4.2.1 The interim report identified potential confusion about responsibilities for the reconciliation of items, including swabs (Health Services Safety Investigations Body, 2023a). To explore this further, the investigation spoke with operating theatre staff and national organisations and found there were varied views.

4.2.2 Most of the scrub practitioners the investigation spoke with felt that the responsibility for swabs and instruments was predominantly placed on them. Many of the scrub practitioners highlighted the link between their responsibilities and professional registration; they felt they had a legal responsibility for tracking surgical items. Scrub practitioners perceived that it came back on them (not the surgeon) if an item went missing.

“… as a scrub practitioner, it is your responsibility. Professionally, legally, you know, we signed to say that these swabs have been removed.”

4.2.3 The surgeons the investigation spoke with felt they were accountable for the patient’s care but that responsibility for certain safety aspects, such as the swab count, could be delegated.

“I'm accountable for what's gone on in that theatre with that patient care under my care. I'm also mostly responsible for all of it. However, you have to delegate tasks.”

4.2.4 Surgeons told the investigation they were reliant on the scrub and circulating practitioner to count swabs but also recognised they had a role in the reconciliation process.

4.2.5 There were also perceptions that ownership of the reconciliation of swabs was shared.

“… the swab reconciliation has ownership on both the surgical side and the scrub practitioner side and the runner [circulating practitioner] side.”

4.2.6 From the hierarchical task analysis (see figure 4) and a review of two other organisations’ analysis of the reconciliation process, the investigation found that there were three roles directly involved in the swab reconciliation process: the surgeon, the scrub practitioner, and the circulating practitioner. The investigation found that the reliability of the reconciliation process is dependent on all three roles and the wider (multidisciplinary) team to help create the optimal conditions for the process.

4.2.7 The investigation found that blame can be inappropriately placed on individual team members when an item goes missing. However, it is evident that the reconciliation process is a team activity and can be influenced by a wide range of interrelating factors.

4.2.8 The investigation found that NatSSIPs emphasises the role of the scrub practitioner and circulating practitioner in its guidance for the prevention of retained foreign objects. While these are key roles in the process, there is scope for making the responsibilities of the surgeon, and other team roles, more explicit in helping to create the time, space, and optimal conditions for the counts to take place. We understand that there are multiple educational resources for all staff on: https://cpoc.org.uk/guideline/guidelines-resources-guidelines/national-safety-standards-invasive-procedures-natssips, including specific short instructions for surgeons, anaesthetists and other staff: https://cpoc.org.uk/sites/cpoc/files/documents/2024-03/CPOC-NatSSIPsS-2Pager_FINAL.pdf [bold text is the amendment to the original report published].

4.2.9 The role of the surgeon in the prevention of retained foreign objects is set out in more detail in the Association for Perioperative Practice’s (2022) standards, however, these standards are not publicly available but are available to purchase, therefore not everyone has access to them.

HSSIB makes the following safety recommendation

Training in roles and responsibilities

4.2.10 Discussions with nurses, operating department practitioners and national stakeholders revealed that some surgeons are not aware of the reconciliation of items policy and their responsibilities for swab reconciliation. The investigation was told by operating theatre staff and national stakeholders that surgeons are not formally trained on swab reconciliation.

4.2.11 Staff also reported that there could be limited understanding of each other’s roles more generally and how decisions could affect other staff members.

4.2.12 Experienced scrub practitioners from several trusts told the investigation that they did not have training where the entire multidisciplinary team were present – that is, nursing staff, operating department practitioners, support staff and surgical staff.

4.2.13 The investigation noted that both NatSSIPs (Centre for Perioperative Care, 2023) and the AfPP standards (Association for Perioperative Practice, 2022) highlight the importance of team members understanding and valuing each other’s roles, understanding team behaviour and human factors. Multidisciplinary team training is recommended in both standards.

HSSIB makes the following safety observation

4.2.14 The investigation recognises that training is a key element within healthcare and is frequently recommended as part of trust serious incident investigation, research with healthcare teams and by national organisations. The investigation sought to bring new insights and explore potentially stronger mitigations (see section 4.3 and 4.4) to reduce the unintended retention of swabs and so did not explore training or the implementation of standards in depth.

4.3.1 This section of the report considers the current level of risk of the occurrence of unintended retained swabs following invasive procedures, whether this risk could feasibly be reduced further, and/or whether the risk is at an acceptable level.

Risk management

4.3.2 The Health and Safety Executive (HSE) (Health and Safety Executive, n.d.a) provides guidance to various industries for assessing and managing risks. Key elements of risk management outlined by the HSE are:

• identifying hazards (things that could cause harm)
• assessing the risks (the likelihood of a hazard causing harm and how much harm may be caused)
• putting in place risk controls as appropriate
• documenting the management decisions
• reviewing the risk controls.

Within risk management there is not an expectation to eliminate all risk, but to reduce risks to ‘as low as reasonably practicable’ (ALARP).

4.3.3 Reducing risks to ALARP involves weighing the risk against the ‘sacrifice’ or ‘efficiency–thoroughness trade-off’ (for example, financial cost, time, loss of productivity, supervision, maintenance) to reduce it (Health and Safety Executive, n.d.b; Hollnagel, 2016). The decision process begins with a presumption that the risk reduction measure should be implemented. It would only be deemed reasonable not to implement the risk reduction measure if it would be ‘grossly disproportionate’ to the benefits that would be achieved. An extreme example is that spending £1m to prevent 5 staff suffering bruised knees would be considered grossly disproportionate (Health and Safety Executive, n.d.b).

4.3.4 The HSE highlights that ALARP does not represent zero risk. Risk is expected to arise from a hazard, and harm can and will occur on occasion. The ‘tolerability’ of the risk is therefore considered. The HSE sets out a framework (illustrated in figure 7) for the ‘tolerability of risk’, considering the level of individual risk and societal concern for reaching a decision on whether risks from an activity or process are unacceptable, tolerable, or broadly acceptable (Health and Safety Executive, 2001). As an example:

‘HSE believes that an individual risk of death of one in a million per annum for both workers and the public corresponds to a very low level of risk and should be used as a guideline for the boundary between the broadly acceptable and tolerable regions.’

(Health and Safety Executive, 2001)

Tolerability and risk appetite

4.3.5 An organisation’s ‘risk appetite’ can be defined as ‘the amount of risk the organisation, or subset of it, is willing to accept’ (Murray-Webster & Office of Government Commerce, 2010).

4.3.6 The investigation explored available data on the impact of the current risk of retained swabs and other foreign objects (such as instruments, needles and guidewires) following invasive procedures and the frequency of such events.

4.3.7 The analysis of common themes from swab retention incident reports, as set out in the interim report, showed that outcomes for the patient included distress, a further invasive procedure to remove the retained swab, prolonged hospitals stays and extended time off work (Health Services Safety Investigations Body, 2023a). The thematic analysis also showed that infection could occur and with that comes a risk to life. However, there are no known deaths associated with retained swabs in the incidents analysed by the investigation.

4.3.8 NHS England Never Event data (see figure 8) shows that the number of swabs (surgical and vaginal) which are unintentionally retained following an invasive procedure appears to have remained at approximately the same level over time. However, Never Event data does not show how the number of retained swab events relates to the number of invasive procedures where there is a potential for a swab to be retained. Never Event data does not show the rates of harm caused by unintentional swab retention or how the current event rate compares to the number of swabs that are used in practice.

4.3.9 The latest data the investigation could find on the number of surgeries each year was from 2013/14. The data indicates there were approximately 4.7 million surgeries conducted in the NHS per year (Royal College of Surgeons of England, n.d.). Using this data, the probability of a retained surgical swab following an invasive procedure is on average 1 in every 270,115 surgeries. In the absence of data, HSSIB took a conservative estimate of 1 in 10 retained swabs resulting in death. This results in a risk to life (RtL) of less than 1 in 1 million, indicating that based on the HSE’s tolerability framework, the risk of harm due to an unintentional retained swab may be deemed to be at an acceptable level for a healthcare organisation. However, the data is outdated, and the number of surgeries may have changed. Other factors would also need to be considered, such as the number of other invasive procedures involving a cavity that is large enough to retain a swab and that harm in healthcare considers more than just risk to life.

4.3.10 Without further data it is difficult to analyse the level of risk and to consider whether it is acceptable and tolerable.

Reducing the risk to ALARP

4.3.11 There are potential mitigations that could reduce the risk of retained foreign objects following an invasive procedure. However, the investigation found that a current barrier to reducing the risk to ALARP, to making changes to the reliability of the process or to accepting the level of risk it holds, is that the NHS does not consider risk in the way HSE describes.

4.3.12 Retained foreign objects, which include swabs, are deemed to be a ‘Never Event’ (NHS Improvement, 2018). As indicated by the name, these events are considered by NHS England as ‘wholly preventable’ and should ‘never’ occur.

4.3.13 The investigation found that the Never Events framework creates anxiety and stigma for staff and organisations. Evidence from the interim report (Health Services Safety Investigations Body, 2023a), analysis of the process and system influences (see reference event and section 4.1) and review of relevant literature (for example D’Lima et al, 2014) demonstrate there are no strong systemic barriers in place to prevent such events. Initial assessment of the risk by HSSIB indicates that the risk may be at a level that is acceptable to a healthcare organisation. HSSIB has recommended that retained swabs no longer be considered a Never Event (Health Services Safety Investigations Body, 2023a). Consideration needs to be given to whether the current risk of retained swabs is acceptable and tolerable to the NHS and whether the risk is being reduced to ALARP.

4.3.14 The investigation was told by various national organisations that there is a concern about removing Never Events from the list and how determining risk appetite (where it is accepted a level of harm will occur) would be perceived by the wider public. It should be noted that public concern is considered when assessing the tolerability of the safety risk (Health and Safety Executive, 2001) and whether the risk is ALARP.

4.3.15 The investigation found that there are challenges in reducing the risk of retained swabs as there is limited understanding about how to effectively reduce and manage risk across the healthcare system, as set out in HSSIB’s report on safety management systems (Health Services Safety Investigations Body, 2023b). Evidence from the interim report’s thematic analysis (Health Services Safety Investigations Body, 2023a) and discussions with national organisations have shown there is a widespread perception that the key mitigation to prevent retained swabs is to improve staff awareness of, and training on, the process. While training and understanding of roles and responsibilities are important mitigations, there is evidence to suggest that staff training alone may not result in a reduction of retained foreign object events (Kaplan et al, 2022). The investigation found that while the current process does prevent some retained swab incidents, it is routinely not compatible with other work processes and is influenced by other system challenges (see section 4.1). Therefore, there are wider system (tools, technology, organisation, task, environment, and people) issues that need to be addressed (Health Services Safety Investigations Body, 2023a).

4.3.16 Another challenge to assessing and reducing the risk of retained swabs to ALARP is that it is unclear who would have overall accountability for reducing the risk. As mentioned, there are two organisations which publish standards for the reconciliation of items, NatSSIPs and the Association for Perioperative Practice, and NHS England provides the framework for Never Events. There is also no multi-level framework that specifies who should be accountable for the management of safety risks across the healthcare system (Health Services Safety Investigations Body, 2023b).

4.3.17 HSIB’s investigation into the harm caused by delays in transferring patients to the right place of care (Healthcare Safety Investigation Branch, 2023) made a safety recommendation to the Department of Health and Social Care to develop and implement a patient safety accountability framework that spans the health and social care system.

4.3.18 In addition, the HSSIB investigation into safety management systems (SMSs) (Health Services Safety Investigations Body, 2023b) made the following safety observation: ‘The oversight of safety management can be improved if relevant bodies, such as providers, commissioners and regulators, adopt a multi-level safety accountability framework.’ This framework would also support the identification of an accountable person for assessing and reducing retained foreign object incidents to ALARP. HSSIB has launched an investigation to further its work on SMSs and will explore multi-level accountability frameworks further (Health Services Safety Investigations Body, 2024). As noted, earlier, the NHS do not consider the concept of ALARP when managing risks. As such a framework to assess if risks are ALARP would need to be developed.

HSSIB makes the following safety recommendation

4.4.1 Incorrect manual counts are responsible for retained foreign objects in approximately 62% to 88% of retained foreign object events (Weprin et al, 2021). It has been suggested that additional tools and/or technology should be used together with traditional counting methods, to reduce incorrect counts (Cochran, 2022; Freitas, 2016).

4.4.2 The investigation explored possible non-technical tools and technology options, specifically radiofrequency identification and barcoding technology.

Non-technical tools to aid swab count

4.4.3 The investigation spoke with scrub practitioners who described that as they become more experienced, the reconciliation of items becomes a more visual-spatial task. They described being able to look down and immediately see if something was missing, because of the way in which they laid out and organised the instrument trollies.

4.4.4 The investigation heard that some trusts are using or have trialled containers known as ‘Swabsafe’ (Nabbi, 2019) which help staff to see the swabs. Each tray is formed of five segments, and one used swab is placed into each segment. The investigation found limited evidence or evaluation of the use of Swabsafe; however, staff reported that it was useful. Staff at one trust described a limitation of Swabsafe in that it created extra financial and environmental costs, and the trays took up space. As such, their trust had stopped using it.

4.4.5 The investigation also heard of other tools that were reported to help staff to see and count swabs but did not investigate these in depth.

4.4.6 A review of the available tools would need to be conducted, balancing patient safety, costs, benefits, efficiency, design and implementation, before their use could be endorsed.

HSSIB makes the following safety observation

Radiofrequency identification

4.4.7 Using automation and computerisation, such as radiofrequency identification (RFID), can potentially provide a more effective intervention to reduce the risk of counting errors, as shown in the hierarchy of intervention effectiveness (see figure 9). Literature shows that the use of RFID technology has been adopted in the USA to support the reconciliation of swabs and surgical instruments.

4.4.8 The benefits of RFID technology are:

• The ability to read multiple tags and identify/track multiple items simultaneously (GS1 UK, 2021).
• RFID tags can be read when out of sight of an RFID reader (for example within the human body) at distances of more than 10 metres (GS1 UK, 2021).

4.4.9 Several studies in the USA have demonstrated the impact of implementing RFID technology into swabs on safety, efficiency, and costs. The key findings from these studies are that RFID technology can:

• Reduce the number of retained swab incidents, near misses and unresolved miscounts (Kaplan et al, 2022; Peng et al, 2023; Primiano et al, 2020; Rupp et al, 2012).
• Improve efficiency (Peng et al, 2023; Primiano et al, 2020; Steelman et al, 2019) and confidence in the count. For example, a survey of 2,285 operations found that 95% of the circulating nurses involved reported that the RFID in swabs improved confidence in the final count (Rupp et al, 2012).
• Reduce costs (Peng et al, 2023; Primiano et al, 2020, Steelman et al, 2019; Weprin, 2021). According to NHS Resolution (2021; 2022; 2023), the cost of claims for ‘foreign body left in situ’ was £21.7m.

4.4.10 There is a potential for error with RFID technology. Retained swab incidents can still occur if the RFID technology is not used consistently and effectively (Williams et al, 2014). It is also not possible to track all items used during an invasive procedure. Small items such as needles cannot be RFID tagged and it is these items that are more difficult to see and more likely to be retained (Peng et al, 2023). Instruments may also break, swabs may be cut and so parts of instruments or swabs could still be unintentionally retained.

Barcoding

4.4.11 Barcoding is another of way tracking items during an invasive procedure to improve the detection of miscounted/misplaced items (Cima et al, 2011; GS1 UK, 2021). Each item (instrument or swab) has its own unique barcode. A scanning device can be used to read the label of each item as it comes into and out of the procedural field (Williams et al, 2014).

4.4.12 The investigation found two research studies which examined barcoding systems for preventing the retention of retained swabs. The studies found that barcode systems detected more discrepancies in swabs counts than the manual count (Cima et al, 2011; Greenberg et al, 2008).

4.4.13 Research literature reports a number of challenges with the use of barcoding swabs and instruments, including:

• Unlike RFID, the barcode scanner cannot read through or detect the presence of a swab inside the patient (Williams et al, 2014).
• There are difficulties with the technology and the time taken to count swabs increased (Greenberg et al, 2008).
• Most manufacturers are currently not barcoding instruments or swabs, which could result in cost implications for trusts (GS1 UK, 2021).
• There is potential for barcodes to degrade over time (Schnock et al, 2021).

4.4.14 Research proposes that RFID technology shows more promise than barcode technology and may be more successful in being implemented (Schnock et al, 2021).

Current drive for digital systems in the NHS

4.4.15 NHS England (2021) has developed a strategy which aims to ‘improve the safety of digital technologies in health and care, now and in the future’ and to ‘identify, and promote the use of digital technologies as solutions to patient safety challenges’. As such, there is potentially an appetite to explore and consider the use of technology for the reconciliation of items during invasive procedures.

4.4.16 Barcode technology, known as ‘Scan4Safety’, already exists in the NHS. The investigation was not aware of any trusts using Scan4Safety to assist in the reconciliation of swabs and instruments. The use of barcode technology in the UK has been shown to release more time for clinical care, reduce costs, improve efficiency and reduce error (Scan4Safety, 2022).

4.4.17 However, as highlighted above, RFID could also be beneficial and has some advantages over barcode systems. As with barcode systems, RFID could also be applied more widely in healthcare where it could improve patient safety, efficiency, costs and reduce error (Kosma et al, 2011; Lamba, 2021; Lo at al, 2007; MSM Solutions, n.d.; Seckman et al, 2017; Wong, 2021).

4.4.18 A comprehensive review of the technology options balancing patient safety, costs, benefits, efficiency, design, implementation and the various ways in which the technology could be used in the NHS would need to be conducted before technology such as RFID could be embraced.

HSSIB makes the following safety recommendation

The investigation was carried out between September 2022 and December 2023. The evidence collected included:

• relevant research literature (for example, D’Lima et al, 2014; Gawande et al, 2003)
• investigation of the reference event, including interviews with staff and observations of two procedures
• conducting a hierarchical task analysis (see figure 4 in the report)
• speaking with other healthcare and academic organisations that have done work on exploring the swab reconciliation process
• analysing 31 serious incident reports (Health Services Safety Investigations Body, 2023)
• conducting a focus group and one-to-one interviews with operating theatre staff from different trusts and surgical specialties
• review of the Healthcare Safety Investigation Branch (2019) investigation report ‘Detection of retained vaginal swabs and tampons following childbirth’
• speaking with relevant national organisations.

Interviews were conducted with staff at the reference event trust 4 months after the incident had occurred. Staff members’ memory of events is useful for understanding perceptions and exploring other contextual factors. However, recall of events is prone to error; details of events can be forgotten, altered, or false memories can unconsciously be added into memory (The British Psychological Society, 2010). The surgical registrar involved in the reference event had left the Trust and so was not available for interview.

The investigation undertook a hierarchical task analysis (HTA) of the swab count process to understand the type and number of tasks involved. The HTA was based on:

• evidence from the Trust’s policy on theatre and maternity swab, instruments and sharps
• observations of a coronary artery bypass graft procedure and a lobectomy (removal of one of the lobes of the lung)
• discussions with operating theatre staff during observations
• interviews with nine theatre staff, including the consultant cardiac surgeon, scrub practitioners, circulating practitioners and operating department practitioner (anaesthetics)
• a focus group with theatre staff to review and refine the HTA.

The investigation identified eight high-level steps that are undertaken as part of the swab count process:

• prepare swabs (before and during surgery)
• track swabs during surgery
• full count of clean, in use and dirty swabs prior to closing a cavity or skin closure (swabs in procedural field only)
• confirm to surgeon that count is correct
• complete WHO (World Health Organization) checklist
• clean swab, red tag and instrument count information off count board
• sign patient care plan that swab and instrument count is correct
• discard all swabs into clinical waste bin.

The investigation identified that there are 67 sub-tasks (see figure 4 in the report), some of which are repeated at various points throughout the procedure. Once developed, the HTA was reviewed in a focus group with operating theatre staff from the refence event Trust.

The AcciMap model was also used to analyse the reference event information and support the direction of the wider investigation. AcciMap (Svedung and Rasmussen, 2002) is an incident analysis method that identifies factors within a system (in this case the healthcare system as a whole) that influence the occurrence of an incident. The analysis focuses on identifying relationships between the different levels of the system (see figure A), which include government policy and budgeting; regulatory bodies and associations; local area management; physical processes and actor activities (linked with staff, people, organisations and systems); equipment and surroundings (Stanton et al, 2013).

AcciMap is useful for visually representing contributory factors across the entire organisational system and their interrelationships. It removes the apportioning of blame to individuals and promotes the development of systematic countermeasures as opposed to countermeasures which focus on an individual (Salmon et al, 2011).

The investigation engaged with stakeholders (see table A) to gather evidence during the investigation. This also enabled checking for factual accuracy and overall sense-checking. The stakeholders contributed to the development of safety recommendations and safety observations based on the evidence gathered.

The investigation engaged with 24 trusts to obtain their serious incident reports for the purpose of the thematic analysis. These trusts were also invited to comment on the investigation’s draft interim report.