A member of hospital staff from the sterile services department cleans surgical instruments, wearing scrubs, hair net, gloves and a mask.

Decontamination of surgical instruments

HSIB legacy content

HSIB legacy content

This investigation was carried out by the Healthcare Safety Investigation Branch (HSIB). Find out more about HSIB legacy.


This investigation focuses on the work of sterile services departments (SSDs).

SSDs are the departments in hospitals where reusable medical equipment is decontaminated (cleaned, disinfected and sterilised) to make it safe before it is used again. Effective decontamination of surgical instruments is essential for patient safety and to avoid delays and inefficiencies in hospital operating theatres.

In particular, the investigation looked at the regulatory framework within which SSDs work, and their use of assurance models, which provide evidence that a service is running according to the relevant policies and procedures. These mechanisms are designed to keep patients safe and enable NHS trusts to manage risk within their organisations.

SSDs are required to have a quality management system in place and many are accredited to the International Organization for Standardization (ISO) standard ‘ISO 13485 Medical devices – quality management’. ‘Health Technical Memorandum 01-01: Management and decontamination of surgical instruments (medical devices) used in acute care’, which is produced by NHS England and NHS Improvement, explains the management of decontamination services and the various ways to sterilise reusable medical devices used in acute care.

To explore how SSDs operate and the related regulatory and assurance mechanisms, the investigation examined a real patient safety incident, referred to as ‘the reference event’. The incident involved a patient who had a procedure to remove a kidney stone. During the procedure foreign material was seen coming out of the end of a surgical instrument.

The investigation’s safety recommendations and safety observations aim to address regulatory and assurance gaps in infection control that prevent risks being identified and managed at an appropriate level, and to remove the confusion caused by the current regulatory structure. They also seek to address the lack of a national competency framework for sterile services staff.

The reference event

A woman aged 56 (the Patient) was diagnosed with a kidney stone in her right kidney. She was seen by a consultant urologist (a doctor who specialises in conditions of the kidneys, bladder and urinary tract), who decided that the Patient needed to have the stone broken up and removed as it was unlikely to pass out of her kidney on its own.

The Patient asked to have a procedure known as a percutaneous nephrolithotomy (PCNL) to remove the kidney stone. This involves making a small incision (cut) on a patient’s back and passing a surgical instrument into their kidney. The Patient gave her consent for an alternative procedure in case of any unforeseen problems with the PCNL.

The Patient was anaesthetised and prepared for the procedure. Once the kidney stone was located, the surgical equipment needed for the procedure was unpacked from its sterile wrappings and inspected by the nurses and the consultant urologist. The equipment looked clean.

An incision was made on the Patient’s skin and the surgical equipment was inserted into her kidney. Water (irrigation) was started, and “black stuff” was seen coming out of the end of the surgical equipment’s irrigation channel. The consultant urologist stopped the procedure immediately and the black material in the kidney was removed. It was later analysed and found to be dried blood.

The kidney stone was successfully removed using the alternative procedure which the Patient had already consented to. As the Patient had been exposed to another person’s dried blood, she was tested for blood-borne viruses; the tests showed no evidence that she had contracted any.

The surgical equipment set used in the Patient’s procedure was classed as ‘reusable’ and therefore needed to be cleaned and decontaminated between each use. The set was made up of several items, including the cleaning brushes needed to make sure that the equipment could be cleaned.

The set had been through a decontamination cycle in the SSD but several of its cleaning brushes were missing. This prevented the set (in particular the irrigation channel) from being cleaned in accordance with the manufacturer’s instructions for use.

The importance of the brushes was not understood by operating theatre staff, who requested the equipment be removed from quarantine (where equipment that has been taken out of use is stored) and decontaminated for the Patient’s procedure.

The investigation identified that there was not a robust assurance process for managing risks associated with the decontamination process and importantly for letting clinical staff know why equipment had been removed from use. The fact that there was only one set of this type of equipment was an additional factor in the decision to release it from quarantine for use in the Patient’s procedure.

National investigation

The investigation identified several gaps in meeting the governance requirements relating to sterile services, more specifically the regulation and assurance frameworks that ensure people are kept safe.

These gaps meant that there was a lack of direct regulatory oversight of SSDs and that NHS trust senior management across the healthcare system did not have systems in place to assure themselves that quality, risks and issues were being managed at an organisational level. While many individual SSDs did have quality management systems in place, NHS trust management did not have an active role in assuring the quality of these services.

The ability to decontaminate surgical equipment was also explored from a design perspective. There are clear requirements in place for decontamination to be considered during the design phase of a surgical instrument. These requirements sit in a complex system that has input from global stakeholders. The investigation heard that if the UK had different standards to the rest of the world, then the cost of equipment would increase.

Staff training and competence was another key area that the investigation considered. It was discovered that all training and training standards for decontamination are set locally by individual SSDs rather than set out in a national framework. This creates challenges for regulators, SSDs and NHS trusts as currently the system of safety relies on trained and experienced staff carrying out decontamination tasks to a set standard and identifying problems as they arise. If the standard of staff training varies across the country, then the standard of decontamination may also vary.


  • There is no requirement to report issues nationally relating to incorrectly decontaminated surgical instruments. This means that the size of the issue is unknown and that the healthcare system does not fully understand the risks and issues it is holding.
  • Risks and issues are held within individual SSDs and are not integrated within wider trust management systems.
  • Trusts frequently focus on clinical risks and not on the risks that arise from non-clinical supporting departments but which present a patient safety risk.
  • There is no national requirement for NHS trusts to have a formalised risk management system.
  • All SSDs produce a similar product – decontaminated surgical instruments. The legal status of an SSD determines which national body regulates it (the Care Quality Commission (CQC) or the Medicines and Healthcare products Regulatory Agency (MHRA)).
  • The CQC does not inspect SSDs for compliance with regulations and standards.
  • The MHRA does not inspect SSDs for compliance with regulations and standards, but relies on external assurance bodies (known as Approved Bodies) to do so. It does undertake a small number of witnessed audits of Approved Bodies while that Approved Body audits an SSD to ensure that standards are being maintained.
  • MHRA-regulated SSDs have in place quality management systems, managed at a local departmental level. ‘Top management’ are not involved in this quality management system, therefore risks and issues relating to SSD quality are not formally escalated to a trust organisational level.
  • Escalation of SSD quality risks and issues relies on the integrity and professional behaviour of managers rather than being required by policy.
  • There is a requirement for manufacturers to design reusable surgical equipment in such a way that it can be decontaminated.
  • Surgical equipment can be difficult to decontaminate due to its complexity and size.
  • Currently the MHRA regulates under the Medical Device Regulations 2002 which incorporate the European Union’s standards and regulations. The MHRA is restricted in developing its own standards due to market forces.
  • To overcome design issues with surgical instruments that relate to decontamination, SSDs rely on decontamination processes to ensure equipment is suitable for use in operating theatres.
  • It is difficult to change the design of equipment after it has been approved for use, so the success of the decontamination processes relies on trained and competent staff.
  • There is no national competency framework for SSD staff to ensure consistency and standardisation.