Surgical errors, including the retention of sponges and other objects, have remained a problem in operating rooms for centuries, despite evolving policies and technology.

  • Retention of foreign objects occurs in about one out of every 1,000 to 8,000 procedures, depending on the study and type of procedure examined.
  • One investigation revealed sponges and surgical instruments are the most commonly retained foreign objects.
  • Mistakes can occur even with new technology, such as data matrix tags and built-in tracking chips.

As recent data show, surgical mistakes, especially retention of sponges and other objects, remain a big problem in the operating room.1-4

“Unintended retention of foreign bodies remains the most frequently reported [surgical] sentinel event for the past three years,” says Victoria M. Steelman, PhD, RN, CNOR, associate professor emeritus at the University of Iowa College of Nursing. Patient falls are the other sentinel event, either first or second in frequency between 2018 and 2020.1

Steelman has conducted several studies on retained objects, including one of 308 sentinel events involving unintentionally retained surgical objects. That retrospective review revealed many surgical instruments were retained, followed by catheters and drains, needles and blades, and packing material.2

Typically, sponges are the most commonly retained object, followed by instruments. These items are left most often in the abdomen or vagina. “The variety of items retained and the number of contributing factors demonstrate the complexity of the issue and [the difficulty of] resolving it,” Steelman notes.

Investigators found most retained instruments were orthopedic. “The most frequently retained single instrument was a uterine manipulator, commonly used in ambulatory surgery,” Steelman reports.

Overall, retention of objects occurs in about one out of every 1,000 to 8,000 surgeries, depending on the study and the type of procedure examined. In one 2008 study of all potential or actual retained foreign objects in surgery reported to a sentinel event phone line or to a website from 2003 to 2006, investigators found there were 68 reported events out of 191,168 operations. This means a potential retained foreign object defect rate of 0.356 per 1,000 patients, and half of these were near-misses. That amounted to a true defect rate of one in 5,500 operations.2,3,5,6

When objects are retained in surgery, the outcomes are serious, including reoperation, a prolonged hospital stay, infection or sepsis, fistula/bowel obstructions, visceral perforation, and death.2,5

“The stress and strain on surgical systems is enormous. The risk to healthcare providers and to patients at time of surgery is considerable,” says Mary Brindle, MD, MPH, director of the Safe Surgery/Safe Systems program at Ariadne Labs.

The World Health Organization (WHO) created a surgical safety checklist in 2009 after WHO recognized the high rate of morbidity and mortality associated with surgery. Brindle was part of a multinational panel that made recommendations for using WHO’s surgical safety checklist during the COVID-19 pandemic. They identified 15 ways surgery centers could adapt procedures and policies during the pandemic.7

“What degree of error do we accept? What is an acceptable rate of death?” Brindle asks. “For example, before we had sterility in surgery, before we understood that sterilizing instruments was important, the mortality rate in amputation was 50%. But at that time, people understood that was the price you pay.”

It took decades for the public commitment to sterility to catch up with the science. People argued about the necessity of sterility, since germs were invisible, and surgical research was in its infancy. “What we accept as the likelihood of dying after surgery changes decade by decade,” Brindle says. “When WHO’s checklist was implemented, the surgical mortality rate was 1.5%, and then it went down to 0.8%.”

Surgical errors can harm patients, and take an emotional toll on staff. It is important for surgery centers to create policies and procedures and train on how to handle and prevent adverse events.

“We felt it was important to examine how different surgeons cope with [surgical] errors,” says Jonathan D’Angelo, PhD, MAEd, assistant professor of surgery and medical education, colon and rectal surgery, at the Mayo Clinic. “It’s an area that’s important, but there’s not robust research on it. Those surgeons who recover from mistakes will have better outcomes.”

Mistakes occur, but to prevent them it is critical to study how surgeons cope after a bad outcome. This field needs more input from a psychological perspective.

“There is no robust curriculum at this point in terms of how we teach trainees on how to handle errors from a psychological perspective,” D’Angelo explains. “Whereas in sports psychology, there are psychologists to help athletes who have trouble with the errors they make, and there is robust research on how athletes deal with error.”

Some of this research could benefit surgeons, perhaps by the dissemination of information about coping techniques that can enhance surgery practice. “When surgeons take a step back upon an error, and take time for a breath ... it’s associated with better overall effectiveness,” D’Angelo explains.

D’Angelo and colleagues distributed an electronic survey to surgical faculty and trainees at several Midwestern academic institutions. Questions centered around themes of coping methods. Researchers found 55% of respondents reported stopping and taking a step back to think as an intraoperative coping technique. Forty-nine percent said they focused on calming themselves to ameliorate their own stress response.8

“The other thing in coping strategies is those who postoperatively report withdrawing from interaction from work and at home after an error tend to report lower overall coping effectiveness,” D’Angelo says. “We left withdrawing up to interpretation in the study, but we think the reader believes it meant [surgeons] did not communicate about the error, but remained silent.”

Another interesting finding was the gender differences in coping methods. “I think it’s important for surgeons to be aware of that, especially if they’re training other surgeons,” D’Angelo says. “In the paper, we discuss how, historically, surgery has been a male-dominated profession, and there still are studies that suggest female surgeons have higher rates of burnout and are subject to bias. We found that males rated their overall coping strategy as more effective than female surgeons rated theirs.”

Also, women reported focusing on calming techniques when making a mistake, and men reported making ergonomic adjustments. Neither were associated with overall coping effectiveness. “Only those who stopped to think rated their coping effectiveness as higher,” D’Angelo adds.

While more evidence-based techniques for surgeons are needed, there already are plenty of evidence-based policies and procedures that surgery centers could follow. “We know how to prevent retained sponges,” Steelman says. “Yet, the evidence-based measures are not employed universally.”

For example, the technology of radiofrequency (RF) sponge detection could eliminate retained sponges. Although surgery centers may choose not to use the safety feature because of cost, comprehensive analyses have shown there is a cost savings when used.

“Sponges have an RF chip,” Steelman explains. “At the end of the procedure, the patient is scanned to determine if a chip is in the patient. If it is, the wound is explored again, and the sponge is removed before the patient leaves the operating room.”

Technology that is well-researched and well-designed can help, but leaders should acknowledge this is a longstanding and complex problem that cannot be entirely solved through policies, education, and technology.

“You have to engineer the safety into the system, like airlines,” says Robert R. Cima, MD, MA, professor of surgery and medical director of the hospital practice for the Mayo Clinic. “You don’t rely on the good will of people; you focus on leadership, teamwork, policies and procedures, and technology.” 


  1. The Joint Commission. Summary data of sentinel events reviewed by The Joint Commission. Statistics as of Jan. 27, 2021.
  2. Steelman VM, Shaw C, Shine L, Hardy-Fairbanks AJ. Unintentionally retained foreign objects: A descriptive study of 308 sentinel events and contributing factors. Jt Comm J Qual Patient Saf 2019;45:249-258.
  3. Cima RR, Newman JS. A historical perspective on the problem of the retained surgical sponge: Have we really come that far? Surgery 2021 Feb 26;S0039-6060(21)00073-8. doi: 10.1016/j.surg.2021.01.035. [Online ahead of print].
  4. Zejnullahu VA, Bicaj BX, Zejnullahu VA, Hamza AR. Retained surgical foreign bodies after surgery. Open Access Maced J Med Sci 2017;5:97-100.
  5. Lincourt AE, Harrell A, Cristiano J, et al. Retained foreign bodies after surgery. J Surg Res 2007;138:170-174.
  6. Cima RR, Kollengode A, Garnatz J, et al. Incidence and characteristics of potential and actual retained foreign object events in surgical patients. J Am Coll Surg 2008;207:80-87.
  7. Panda N, Etheridge JC, Singh T, et al. We asked the experts: The WHO surgical safety checklist and the COVID-19 pandemic: Recommendations for content and implementation adaptations. World J Surg 2021;45:1293-1296.
  8. D’Angelo JD, Lund S, Busch RA, et al. Coping with errors in the operating room: Intraoperative strategies, postoperative strategies, and sex differences. Surgery 2021 Mar 30;S0039-6060(21)00155-0. doi: 10.1016/j.surg.2021.02.035. [Online ahead of print].