■ Safety of care:

Improving patient safety and reducing risks

Mitigating the risk of retained foreign bodies during surgery

Close-up of scrub nurse taking medical instruments

5 minutes

Published: December 2021

The information in this article was correct at the time of publishing

The Canadian Institute for Health Information has reported that, in 2017, the rate of a foreign body being left in a patient during a procedure had increased 14% over five years.1 Over the same decade, the CMPA closed a median of 20 cases per year involving unintentionally retained foreign bodies following medical or surgical care.2

To identify learning opportunities for surgical teams, the CMPA analyzed a subset of its closed medico-legal cases. Our analysis identified 28 civil legal cases (closed from 2015 to 2019) involving retained foreign bodies introduced in a hospital operating room and subsequently overlooked. Two takeaways were clear:

  • Multiple safeguards are needed.
  • Prevention is a shared responsibility between surgeons and teams.

What happened in the CMPA cases?

In all of the CMPA cases reviewed, patients experienced physical harm and sometimes psychological harm (including post-traumatic stress disorder and depression) as a result of a retained foreign body. Consistent with the literature,3 most of the incidents involved a retained sponge (19/28, 68%), while others involved a retained instrument, sharp, or miscellaneous item. Abdominal surgery featured prominently among the cases (17/28, 61%), with knee, breast, gynecologic, and spine surgery also represented.4

The peer experts who reviewed the medico-legal cases5 typically noted a deviation from a hospital policy or procedure (25/28 cases, 89%), which is a known risk factor for retained foreign bodies.6 The deviations often related to the surgical count, such as not adding extra (non-routine) items to the count sheet or inadvertently not checking off an item on the count sheet. There were also clinical judgment issues. These possibilities for human error suggest that multiple safeguards are needed to mitigate risk.

Case scenario:7 A sponge remains inside a patient despite multiple attempts to locate it

A patient with L2-L3 disc herniation is undergoing a microdiscectomy. The team encounters bleeding from the epidural veins, and the surgeon controls it using cottonoid patties. At the end of surgery, the nurse announces a discrepancy in the sponge count. The surgeon visually inspects the operative field using a microscope but cannot see the patty; he concludes that it must have been caught in the drapes. Once the incision is closed, the team orders a portable intra-operative X-ray as per protocol when the count is incorrect. The surgeon reviews the X-ray image and sees no evidence of the patty. He files an incident report. Days later, a radiologist notes a small radio-opaque area on the film—possibly a retained sponge. However, the surgeon does not receive the radiologist’s report.

With chronic pain months later, the patient initiates a civil legal action against the surgeon for failing to locate and remove the patty intra-operatively. Peer expert reviewers in the case note that the patty was easily visible on the intra-operative X-ray film. The patient receives a settlement from the CMPA on behalf of the surgeon for failing to identify the patty and from the hospital for failing to deliver the radiology report.

How can surgeons enhance patient safety?

1. Use more than one strategy for prevention

Although manual surgical counts, methodical wound exploration, and radiographic imaging are all accepted strategies for prevention, the case scenario shows that each step on its own can be prone to error. Prevention therefore needs multiple layers of protection, with each layer optimized. Augmented or supplemental strategies may help. In the case scenario, for example—when there was no clear reason for the discrepant count—it may have been possible for the neurosurgeon to augment the X-ray protocol by contacting a radiologist for a second opinion before closing.

Post-operative orders should be clear

Certain items, such wound packing, are purposefully left in by the surgical team. The CMPA has identified cases in which the patient and post-operative care provider were unaware of packing and patients experienced harm as a result. As a surgeon communicating to the post-operative care team, be explicit in your instructions on what to replace or remove. To avoid misunderstandings, distinguish between “packing” inside the wound and “dressing” on top of the wound.

2. Consider whether radiographic imaging is required when the risk of a retained foreign body is high

The Operating Room Nurses Association of Canada has published operative factors that can alert OR teams to the possibility of a retained foreign body in addition to discrepant surgical counts.6 Some of these factors were present in the CMPA cases reviewed, namely: patients with increased body mass index, urgent surgeries, extended surgery times, unplanned procedures, high-volume blood loss, multiple surgical teams, and a nursing shift change. As an added safety measure, assess the need for radiographic imaging when these or other risk factors are present.

3. Consider other options to augment the surgical count

Radiofrequency tags and wands (for tracking and locating retained items) and bar codes (for tracking items before and after surgery) are options to augment the surgical count and potentially reduce the need for intra-operative X-rays. There is some evidence, mainly from non-randomized studies, that the rate of retained foreign bodies is lower when using these technologies and that radiofrequency technology in particular is associated with lower healthcare costs.8,9 These technologies, however, are only one layer of protection intended to complement, rather than replace, other modalities.

4. Foster psychological safety

When team members are reluctant to speak up, an OR prevention strategy becomes less effective. In the case scenario, for example, it is conceivable that the nurse thought it prudent to obtain a radiologist’s interpretation of the X-ray film, but did not express that opinion out of fear of being ridiculed or ignored.

To foster psychological safety, reflect on how to create the best conditions for teams to speak up, and be open and encouraging when a team member voices concern about a missing item. Engage consistently during the Surgical Safety Checklist, and minimize distractions to show you are engaged in the importance of this safety procedure.

The surgical count should be given undivided attention

Interruptions and distractions in the OR have been linked to a deterioration of the non-technical performance of surgical teams.10 Consider a formal pause for the surgical count before closing, as is policy in some institutions.

The bottom line

Despite standardized surgical counts and widespread use of the Surgical Safety Checklist in Canada, the prevention of retained foreign bodies during surgery continues to be a challenge. By following institutional policies and procedures for prevention, and by identifying and addressing vulnerabilities in those policies and procedures, you can help to mitigate the risks of a retained foreign body. Above all, foster psychological safety in the OR and be fully engaged with the strategies for prevention.


  1. Healthcare Excellence Canada [Internet]. Ottawa (CA): Canadian Institute for Health Information and Canadian Patient Safety Institute; 2020. Hospital Harm Improvement Resource: Retained Foreign Body [cited 2021 August 5]. Available from: https://www.patientsafetyinstitute.ca/en/toolsResources/Hospital-Harm-Measure/Improvement-Resources/Retained%20Foreign%20Body-Introduction/Documents/HHIR-Retained-Foreign-Body-D24.pdf
  2. The median value is for cases closed at the CMPA from 2010 to 2019 inclusive. The CMPA defines retained foreign bodies as medical or surgical items retained accidentally in a wound or body cavity, or items retained intentionally for a specified period with retrieval unintentionally delayed or not performed.
  3. Hempel S, Maggard-Gibbons M, Nguyen DK et al. Wrong-Site Surgery, Retained Surgical Items, and Surgical Fires: A Systematic Review of Surgical Never Events. JAMA Surg. 2015 Aug;150(8):796-805. doi: 10.1001/jamasurg.2015.0301.
  4. Gynecologic surgeries that did not involve labour-and-delivery were included in the CMPA analysis; labour-and-delivery cases were excluded.
  5. Peer experts refer to physicians retained by the parties in a legal action to interpret and provide their opinion on clinical, scientific, or technical issues surrounding the care provided. These individuals are typically of similar training and experience as the physicians whose care they are reviewing.
  6. Operating Room Nurses Association of Canada. The ORNAC Standards, Guidelines, and Position Statements for Perioperative Registered Nurses: 15th edition. (CA): Operating Room Nurses Association of Canada; 2021. Available from: www.ornac.ca
  7. This case scenario is based on an actual medico-legal case. However, certain facts were omitted, changed, or added for illustrative purposes and to protect the confidentiality of the parties involved.
  8. Rapid Response Report: Summary of Abstracts. Ottawa (ON): Canadian Agency for Drugs and Technologies in Health; Apr 2015. Project Number: RB0826-000. Available from: https://www.cadth.ca/automated-counting-technology-surgical-counts-clinical-effectiveness-cost-effectiveness-and
  9. Steelman VM, Schaapveld AG, Storm HE et al. The Effect of Radiofrequency Technology on Time Spent Searching for Surgical Sponges and Associated Costs. AORN J. 2019 Jun;109(6):718-727. doi: 10.1002/aorn.12698.
  10. Gillespie BM, Harbeck E, Kang E et al. Correlates of non-technical skills in surgery: a prospective study. BMJ Open. 2017 Jan 30;7(1):e014480. doi: 10.1136/bmjopen-2016-014480

DISCLAIMER: The information contained in this learning material is for general educational purposes only and is not intended to provide specific professional medical or legal advice, nor to constitute a "standard of care" for Canadian healthcare professionals. The use of CMPA learning resources is subject to the foregoing as well as the CMPA's Terms of Use.